nih-gov/www.ncbi.nlm.nih.gov/books/n/livertox/Tolcapone/index.html

611 lines
No EOL
121 KiB
HTML
Raw Blame History

This file contains ambiguous Unicode characters

This file contains Unicode characters that might be confused with other characters. If you think that this is intentional, you can safely ignore this warning. Use the Escape button to reveal them.

<?xml version="1.0" encoding="utf-8"?>
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head><meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<!-- AppResources meta begin -->
<meta name="paf-app-resources" content="" />
<script type="text/javascript">var ncbi_startTime = new Date();</script>
<!-- AppResources meta end -->
<!-- TemplateResources meta begin -->
<meta name="paf_template" content="" />
<!-- TemplateResources meta end -->
<!-- Logger begin -->
<meta name="ncbi_db" content="books" /><meta name="ncbi_pdid" content="book-part" /><meta name="ncbi_acc" content="NBK548573" /><meta name="ncbi_domain" content="livertox" /><meta name="ncbi_report" content="record" /><meta name="ncbi_type" content="fulltext" /><meta name="ncbi_objectid" content="" /><meta name="ncbi_pcid" content="/NBK548573/" /><meta name="ncbi_pagename" content="Tolcapone - LiverTox - NCBI Bookshelf" /><meta name="ncbi_bookparttype" content="chapter" /><meta name="ncbi_app" content="bookshelf" />
<!-- Logger end -->
<title>Tolcapone - LiverTox - NCBI Bookshelf</title>
<!-- AppResources external_resources begin -->
<link rel="stylesheet" href="/core/jig/1.15.2/css/jig.min.css" /><script type="text/javascript" src="/core/jig/1.15.2/js/jig.min.js"></script>
<!-- AppResources external_resources end -->
<!-- Page meta begin -->
<meta name="robots" content="INDEX,FOLLOW,NOARCHIVE" /><meta name="citation_inbook_title" content="LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]" /><meta name="citation_title" content="Tolcapone" /><meta name="citation_publisher" content="National Institute of Diabetes and Digestive and Kidney Diseases" /><meta name="citation_date" content="2021/10/25" /><meta name="citation_pmid" content="31643888" /><meta name="citation_fulltext_html_url" content="https://www.ncbi.nlm.nih.gov/books/NBK548573/" /><link rel="schema.DC" href="http://purl.org/DC/elements/1.0/" /><meta name="DC.Title" content="Tolcapone" /><meta name="DC.Type" content="Text" /><meta name="DC.Publisher" content="National Institute of Diabetes and Digestive and Kidney Diseases" /><meta name="DC.Date" content="2021/10/25" /><meta name="DC.Identifier" content="https://www.ncbi.nlm.nih.gov/books/NBK548573/" /><meta name="description" content="Tolcapone is a catechol-O-methyltransferase inhibitor used in the therapy of Parkinson disease as adjunctive therapy in combination with levodopa and carbidopa. Tolcapone has been associated with serum enzyme elevations during treatment and with several instances of clinically apparent acute liver injury, which can be severe and even fatal." /><meta name="og:title" content="Tolcapone" /><meta name="og:type" content="book" /><meta name="og:description" content="Tolcapone is a catechol-O-methyltransferase inhibitor used in the therapy of Parkinson disease as adjunctive therapy in combination with levodopa and carbidopa. Tolcapone has been associated with serum enzyme elevations during treatment and with several instances of clinically apparent acute liver injury, which can be severe and even fatal." /><meta name="og:url" content="https://www.ncbi.nlm.nih.gov/books/NBK548573/" /><meta name="og:site_name" content="NCBI Bookshelf" /><meta name="og:image" content="https://www.ncbi.nlm.nih.gov/corehtml/pmc/pmcgifs/bookshelf/thumbs/th-livertox-lrg.png" /><meta name="twitter:card" content="summary" /><meta name="twitter:site" content="@ncbibooks" /><meta name="bk-non-canon-loc" content="/books/n/livertox/Tolcapone/" /><link rel="canonical" href="https://www.ncbi.nlm.nih.gov/books/NBK548573/" /><link rel="stylesheet" href="/corehtml/pmc/css/figpopup.css" type="text/css" media="screen" /><link rel="stylesheet" href="/corehtml/pmc/css/bookshelf/2.26/css/books.min.css" type="text/css" /><link rel="stylesheet" href="/corehtml/pmc/css/bookshelf/2.26/css/books_print.min.css" type="text/css" media="print" /><style type="text/css">p a.figpopup{display:inline !important} .bk_tt {font-family: monospace} .first-line-outdent .bk_ref {display: inline} .body-content h2, .body-content .h2 {border-bottom: 1px solid #97B0C8} .body-content h2.inline {border-bottom: none} a.page-toc-label , .jig-ncbismoothscroll a {text-decoration:none;border:0 !important} .temp-labeled-list .graphic {display:inline-block !important} .temp-labeled-list img{width:100%}</style><script type="text/javascript" src="/corehtml/pmc/js/jquery.hoverIntent.min.js"> </script><script type="text/javascript" src="/corehtml/pmc/js/common.min.js?_=3.18"> </script><script type="text/javascript" src="/corehtml/pmc/js/large-obj-scrollbars.min.js"> </script><script type="text/javascript">window.name="mainwindow";</script><script type="text/javascript" src="/corehtml/pmc/js/bookshelf/2.26/book-toc.min.js"> </script><script type="text/javascript" src="/corehtml/pmc/js/bookshelf/2.26/books.min.js"> </script><meta name="book-collection" content="NONE" />
<!-- Page meta end -->
<link rel="shortcut icon" href="//www.ncbi.nlm.nih.gov/favicon.ico" /><meta name="ncbi_phid" content="CE8E1D537C8D7A910000000000EF00D0.m_13" />
<meta name='referrer' content='origin-when-cross-origin'/><link type="text/css" rel="stylesheet" href="//static.pubmed.gov/portal/portal3rc.fcgi/4216699/css/3852956/3985586/3808861/4121862/3974050/3917732/251717/4216701/14534/45193/4113719/3849091/3984811/3751656/4033350/3840896/3577051/3852958/4008682/4207974/4206132/4062871/12930/3964959/3854974/36029/4128070/9685/3549676/3609192/3609193/3609213/3395586.css" /><link type="text/css" rel="stylesheet" href="//static.pubmed.gov/portal/portal3rc.fcgi/4216699/css/3411343/3882866.css" media="print" /></head>
<body class="book-part">
<div class="grid">
<div class="col twelve_col nomargin shadow">
<!-- System messages like service outage or JS required; this is handled by the TemplateResources portlet -->
<div class="sysmessages">
<noscript>
<p class="nojs">
<strong>Warning:</strong>
The NCBI web site requires JavaScript to function.
<a href="/guide/browsers/#enablejs" title="Learn how to enable JavaScript" target="_blank">more...</a>
</p>
</noscript>
</div>
<!--/.sysmessage-->
<div class="wrap">
<div class="page">
<div class="top">
<div id="universal_header">
<section class="usa-banner">
<div class="usa-accordion">
<header class="usa-banner-header">
<div class="usa-grid usa-banner-inner">
<img src="https://www.ncbi.nlm.nih.gov/coreutils/uswds/img/favicons/favicon-57.png" alt="U.S. flag" />
<p>An official website of the United States government</p>
<button class="non-usa-accordion-button usa-banner-button" aria-expanded="false" aria-controls="gov-banner-top" type="button">
<span class="usa-banner-button-text">Here's how you know</span>
</button>
</div>
</header>
<div class="usa-banner-content usa-grid usa-accordion-content" id="gov-banner-top" aria-hidden="true">
<div class="usa-banner-guidance-gov usa-width-one-half">
<img class="usa-banner-icon usa-media_block-img" src="https://www.ncbi.nlm.nih.gov/coreutils/uswds/img/icon-dot-gov.svg" alt="Dot gov" />
<div class="usa-media_block-body">
<p>
<strong>The .gov means it's official.</strong>
<br />
Federal government websites often end in .gov or .mil. Before
sharing sensitive information, make sure you're on a federal
government site.
</p>
</div>
</div>
<div class="usa-banner-guidance-ssl usa-width-one-half">
<img class="usa-banner-icon usa-media_block-img" src="https://www.ncbi.nlm.nih.gov/coreutils/uswds/img/icon-https.svg" alt="Https" />
<div class="usa-media_block-body">
<p>
<strong>The site is secure.</strong>
<br />
The <strong>https://</strong> ensures that you are connecting to the
official website and that any information you provide is encrypted
and transmitted securely.
</p>
</div>
</div>
</div>
</div>
</section>
<div class="usa-overlay"></div>
<header class="ncbi-header" role="banner" data-section="Header">
<div class="usa-grid">
<div class="usa-width-one-whole">
<div class="ncbi-header__logo">
<a href="/" class="logo" aria-label="NCBI Logo" data-ga-action="click_image" data-ga-label="NIH NLM Logo">
<img src="https://www.ncbi.nlm.nih.gov/coreutils/nwds/img/logos/AgencyLogo.svg" alt="NIH NLM Logo" />
</a>
</div>
<div class="ncbi-header__account">
<a id="account_login" href="https://account.ncbi.nlm.nih.gov" class="usa-button header-button" style="display:none" data-ga-action="open_menu" data-ga-label="account_menu">Log in</a>
<button id="account_info" class="header-button" style="display:none" aria-controls="account_popup" type="button">
<span class="fa fa-user" aria-hidden="true">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 24 24" width="20px" height="20px">
<g style="fill: #fff">
<ellipse cx="12" cy="8" rx="5" ry="6"></ellipse>
<path d="M21.8,19.1c-0.9-1.8-2.6-3.3-4.8-4.2c-0.6-0.2-1.3-0.2-1.8,0.1c-1,0.6-2,0.9-3.2,0.9s-2.2-0.3-3.2-0.9 C8.3,14.8,7.6,14.7,7,15c-2.2,0.9-3.9,2.4-4.8,4.2C1.5,20.5,2.6,22,4.1,22h15.8C21.4,22,22.5,20.5,21.8,19.1z"></path>
</g>
</svg>
</span>
<span class="username desktop-only" aria-hidden="true" id="uname_short"></span>
<span class="sr-only">Show account info</span>
</button>
</div>
<div class="ncbi-popup-anchor">
<div class="ncbi-popup account-popup" id="account_popup" aria-hidden="true">
<div class="ncbi-popup-head">
<button class="ncbi-close-button" data-ga-action="close_menu" data-ga-label="account_menu" type="button">
<span class="fa fa-times">
<svg xmlns="http://www.w3.org/2000/svg" viewBox="0 0 48 48" width="24px" height="24px">
<path d="M38 12.83l-2.83-2.83-11.17 11.17-11.17-11.17-2.83 2.83 11.17 11.17-11.17 11.17 2.83 2.83 11.17-11.17 11.17 11.17 2.83-2.83-11.17-11.17z"></path>
</svg>
</span>
<span class="usa-sr-only">Close</span></button>
<h4>Account</h4>
</div>
<div class="account-user-info">
Logged in as:<br />
<b><span class="username" id="uname_long">username</span></b>
</div>
<div class="account-links">
<ul class="usa-unstyled-list">
<li><a id="account_myncbi" href="/myncbi/" class="set-base-url" data-ga-action="click_menu_item" data-ga-label="account_myncbi">Dashboard</a></li>
<li><a id="account_pubs" href="/myncbi/collections/bibliography/" class="set-base-url" data-ga-action="click_menu_item" data-ga-label="account_pubs">Publications</a></li>
<li><a id="account_settings" href="/account/settings/" class="set-base-url" data-ga-action="click_menu_item" data-ga-label="account_settings">Account settings</a></li>
<li><a id="account_logout" href="/account/signout/" class="set-base-url" data-ga-action="click_menu_item" data-ga-label="account_logout">Log out</a></li>
</ul>
</div>
</div>
</div>
</div>
</div>
</header>
<div role="navigation" aria-label="access keys">
<a id="nws_header_accesskey_0" href="https://www.ncbi.nlm.nih.gov/guide/browsers/#ncbi_accesskeys" class="usa-sr-only" accesskey="0" tabindex="-1">Access keys</a>
<a id="nws_header_accesskey_1" href="https://www.ncbi.nlm.nih.gov" class="usa-sr-only" accesskey="1" tabindex="-1">NCBI Homepage</a>
<a id="nws_header_accesskey_2" href="/myncbi/" class="set-base-url usa-sr-only" accesskey="2" tabindex="-1">MyNCBI Homepage</a>
<a id="nws_header_accesskey_3" href="#maincontent" class="usa-sr-only" accesskey="3" tabindex="-1">Main Content</a>
<a id="nws_header_accesskey_4" href="#" class="usa-sr-only" accesskey="4" tabindex="-1">Main Navigation</a>
</div>
<section data-section="Alerts">
<div class="ncbi-alerts-placeholder"></div>
</section>
</div>
<div class="header">
<div class="res_logo"><h1 class="res_name"><a href="/books/" title="Bookshelf home">Bookshelf</a></h1><h2 class="res_tagline"></h2></div>
<div class="search"><form method="get" action="/books/"><div class="search_form"><label for="database" class="offscreen_noflow">Search database</label><select id="database"><optgroup label="Recent"><option value="books" selected="selected" data-ac_dict="bookshelf-search">Books</option><option value="pubmed">PubMed</option><option value="clinvar">ClinVar</option><option value="gquery" class="last">All Databases</option></optgroup><optgroup label="All"><option value="gquery">All Databases</option><option value="assembly">Assembly</option><option value="biocollections">Biocollections</option><option value="bioproject">BioProject</option><option value="biosample">BioSample</option><option value="books" data-ac_dict="bookshelf-search">Books</option><option value="clinvar">ClinVar</option><option value="cdd">Conserved Domains</option><option value="gap">dbGaP</option><option value="dbvar">dbVar</option><option value="gene">Gene</option><option value="genome">Genome</option><option value="gds">GEO DataSets</option><option value="geoprofiles">GEO Profiles</option><option value="gtr">GTR</option><option value="ipg">Identical Protein Groups</option><option value="medgen">MedGen</option><option value="mesh">MeSH</option><option value="nlmcatalog">NLM Catalog</option><option value="nuccore">Nucleotide</option><option value="omim">OMIM</option><option value="pmc">PMC</option><option value="protein">Protein</option><option value="proteinclusters">Protein Clusters</option><option value="protfam">Protein Family Models</option><option value="pcassay">PubChem BioAssay</option><option value="pccompound">PubChem Compound</option><option value="pcsubstance">PubChem Substance</option><option value="pubmed">PubMed</option><option value="snp">SNP</option><option value="sra">SRA</option><option value="structure">Structure</option><option value="taxonomy">Taxonomy</option><option value="toolkit">ToolKit</option><option value="toolkitall">ToolKitAll</option><option value="toolkitbookgh">ToolKitBookgh</option></optgroup></select><div class="nowrap"><label for="term" class="offscreen_noflow" accesskey="/">Search term</label><div class="nowrap"><input type="text" name="term" id="term" title="Search Books. Use up and down arrows to choose an item from the autocomplete." value="" class="jig-ncbiclearbutton jig-ncbiautocomplete" data-jigconfig="dictionary:'bookshelf-search',disableUrl:'NcbiSearchBarAutoComplCtrl'" autocomplete="off" data-sbconfig="ds:'no',pjs:'no',afs:'no'" /></div><button id="search" type="submit" class="button_search nowrap" cmd="go">Search</button></div></div></form><ul class="searchlinks inline_list"><li>
<a href="/books/browse/">Browse Titles</a>
</li><li>
<a href="/books/advanced/">Advanced</a>
</li><li class="help">
<a href="/books/NBK3833/">Help</a>
</li><li class="disclaimer">
<a target="_blank" data-ga-category="literature_resources" data-ga-action="link_click" data-ga-label="disclaimer_link" href="https://www.ncbi.nlm.nih.gov/books/about/disclaimer/">Disclaimer</a>
</li></ul></div>
</div>
<!--<component id="Page" label="headcontent"/>-->
</div>
<div class="content">
<!-- site messages -->
<!-- Custom content 1 -->
<div class="col1">
</div>
<div class="container">
<div id="maincontent" class="content eight_col col">
<!-- Custom content in the left column above book nav -->
<div class="col2">
</div>
<!-- Book content -->
<!-- Custom content between navigation and content -->
<div class="col3">
</div>
<div class="document">
<div class="pre-content"><div><div class="bk_prnt"><p class="small">NCBI Bookshelf. A service of the National Library of Medicine, National Institutes of Health.</p><p>LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012-. </p></div><div class="iconblock clearfix whole_rhythm no_top_margin bk_noprnt"><a class="img_link icnblk_img" title="All Drug Records" href="/books/n/livertox/"><img class="source-thumb" src="/corehtml/pmc/pmcgifs/bookshelf/thumbs/th-livertox-lrg.png" alt="Cover of LiverTox" height="100px" width="80px" /></a><div class="icnblk_cntnt eight_col"><h2>LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet].</h2><a data-jig="ncbitoggler" href="#__NBK548573_dtls__">Show details</a><div style="display:none" class="ui-widget" id="__NBK548573_dtls__"><div>Bethesda (MD): <a href="https://www.niddk.nih.gov/" ref="pagearea=page-banner&amp;targetsite=external&amp;targetcat=link&amp;targettype=publisher">National Institute of Diabetes and Digestive and Kidney Diseases</a>; 2012-.</div></div><div class="half_rhythm"><ul class="inline_list"><li style="margin-right:1em"><a class="bk_cntns" href="/books/n/livertox/">Drug Records</a></li></ul></div><div class="bk_noprnt"><form method="get" action="/books/n/livertox/" id="bk_srch"><div class="bk_search"><label for="bk_term" class="offscreen_noflow">Search term</label><input type="text" title="Search this book" id="bk_term" name="term" value="" data-jig="ncbiclearbutton" /> <input type="submit" class="jig-ncbibutton" value="Search this book" submit="false" style="padding: 0.1em 0.4em;" /></div></form></div></div><div class="icnblk_cntnt two_col"><div class="pagination bk_noprnt"><a class="active page_link prev" href="/books/n/livertox/Tofacitinib/" title="Previous page in this title">&lt; Prev</a><a class="active page_link next" href="/books/n/livertox/Tolmetin/" title="Next page in this title">Next &gt;</a></div></div></div></div></div>
<div class="main-content lit-style" itemscope="itemscope" itemtype="http://schema.org/CreativeWork"><div class="meta-content fm-sec"><h1 id="_NBK548573_"><span class="title" itemprop="name">Tolcapone</span></h1><p class="small">Last Update: <span itemprop="dateModified">October 25, 2021</span>.</p></div><div class="body-content whole_rhythm" itemprop="text"><div id="Tolcapone.OVERVIEW"><h2 id="_Tolcapone_OVERVIEW_">OVERVIEW</h2><div id="Tolcapone.Introduction"><h3>Introduction</h3><p>Tolcapone is a catechol-O-methyltransferase inhibitor used in the therapy of Parkinson disease as adjunctive therapy in combination with levodopa and carbidopa. Tolcapone has been associated with serum enzyme elevations during treatment and with several instances of clinically apparent acute liver injury, which can be severe and even fatal.</p></div><div id="Tolcapone.Background"><h3>Background</h3><p>Tolcapone (tol' ka pone) is a specific inhibitor of cathechol-O-methyltransferase (COMT), which is a major enzyme in the pathway of levodopa metabolism. As a result, tolcapone slows the metabolism of levodopa and results in an increase in its bioavailability and duration of action. Tolcapone inhibits COMT activity both peripherally and in the central nervous system. Tolcapone was approved for use in the United States in 1998 for the therapy of symptomatic Parkinson disease as an adjunct to levodopa/carbidopa therapy in patients with motor complications. Soon after its approval, it was withdrawn after several instances of acute liver failure were attributed to its use. Subsequently tolcapone was reintroduced, but with requirements for informing patients about the possibility of liver injury and rigorous monitoring of serum enzymes during treatment. Tolcapone is recommended only for patients who fail to respond to other conventional adjunctive therapies in patients who experience episodes of motor abnormalities (&#x0201c;off&#x0201d; episodes) while receiving levodopa therapy. Two other COMT inhibitors have been approved that have not been associated with liver injury, and tolcapone is now rarely used. Tolcapone remains available in tablets of 100 mg generically and under the brand name of Tasmar. Tolcapone is typically initiated in doses of 100 mg three times daily, with adjustment upwards based upon tolerance and clinical effects to a maximum of 600 mg daily. Common side effects include somnolence, dizziness, confusion, dyskinesia, vivid dreams, hallucinations, depression, fatigue, headache, diarrhea and gastrointestinal upset, symptoms that are typical of dopaminergic stimulation and enhanced effects of levodopa. Severe adverse events can include hypotension, syncope, psychotic behaviors, poor impulse control, hallucinations, diarrhea, colitis, rhabdomyolysis, and severe hepatotoxicity.</p></div><div id="Tolcapone.Hepatotoxicity"><h3>Hepatotoxicity</h3><p>Tolcapone has been reported to cause serum aminotransferase elevations above 3 times the upper limit of normal in 1% to 5% of patients. While these abnormalities are usually asymptomatic and self-limiting, some persist if therapy is continued and resolved only with stopping tolcapone. More importantly, tolcapone has been implicated in several cases of severe, clinically apparent acute liver injury and at least three cases of death from acute liver failure. The onset of injury was insidious, arising 1 to 5 months after starting treatment. The pattern of serum enzyme elevations was hepatocellular and the clinical phenotype was similar to acute viral hepatitis. Immunoallergic manifestations were not present, but some patients had autoantibodies of unclear significance. Because of these reports, regular monitoring of serum aminotransferase levels has been mandated (every 2 to 4 weeks for the first 6 months of treatment and as clinically indicated thereafter) during tolcapone therapy, and treatment should be promptly discontinued if <a class="def" href="/books/n/livertox/glossary/def-item/glossary.alanine-aminotransferase-alt-/">ALT</a> or <a class="def" href="/books/n/livertox/glossary/def-item/glossary.aspartate-aminotransferase-ast-/">AST</a> levels rise above twice the upper limit of the normal range or if signs or symptoms of liver injury are present.</p><p><a class="def" href="/books/n/livertox/glossary/def-item/glossary.likelihood-score/">Likelihood score</a>: C (probable cause of clinically apparent liver injury).</p></div><div id="Tolcapone.Mechanism_of_Injury"><h3>Mechanism of Injury</h3><p>Tolcapone is metabolized extensively in the liver and undergoes glucuronidation prior to excretion. The hepatotoxicity of tolcapone is likely due to production of a toxic intermediate that overwhelms the usual protective mechanisms of excretion. Increased likelihood of hepatic injury due to tolcapone has been linked to variants of the gene that is responsible for glucuronidation, UDP-glucuronosyl transferase.</p></div><div id="Tolcapone.Outcome_and_Management"><h3>Outcome and Management</h3><p>Liver injury caused by tolcapone ranges from mild, transient and asymptomatic serum enzyme elevations to clinically apparent hepatitis and acute liver failure. Tolcapone therapy has not been associated with chronic hepatitis or vanishing bile duct syndrome. Therapy of acute liver failure due to medications is largely supportive, but infusions of n-acetyl cysteine may be beneficial if given early. In at least one case report of acute liver failure due to tolcapone, autoimmune features led to the use of corticosteroids which appeared to be beneficial. Because of the propensity for tolcapone to cause acute liver failure, routine testing for serum aminotransferase levels should be done every 2 to 4 weeks for 6 months after initiation of therapy and as clinically indicated thereafter. Tolcapone should be discontinued if <a class="def" href="/books/n/livertox/glossary/def-item/glossary.alanine-aminotransferase-alt-/">ALT</a> or <a class="def" href="/books/n/livertox/glossary/def-item/glossary.aspartate-aminotransferase-ast-/">AST</a> levels rise above twice the upper limit of the normal range or if any signs and symptoms suggestive of liver injury appear. There does not appear to be cross sensitivity to hepatic injury between tolcapone and entacapone, a COMT inhibitor with a similar chemical structure.</p><p>Drug Class: <a href="/books/n/livertox/AntiparkinsonAgents/">Parkinson Disease Agents</a></p><p>Other Drugs in the Subclass, COMT Inhibitors: <a href="/books/n/livertox/Entacapone/">Entacapone</a>, <a href="/books/n/livertox/Opicapone/">Opicapone</a></p></div></div><div id="Tolcapone.CASE_REPORT"><h2 id="_Tolcapone_CASE_REPORT_">CASE REPORT</h2><div id="Tolcapone.Case_1_Acute_liver_failure_att"><h3>Case 1. Acute liver failure attributed to tolcapone.(<a class="bk_pop" href="#Tolcapone.REF.1">1</a>-<a class="bk_pop" href="#Tolcapone.REF.3">3</a>)</h3><p>A 74 year old woman with Parkinson disease developed jaundice 8 weeks after being switched from amantadine to tolcapone (100 mg twice daily), because of motor fluctuations during long term levodopa therapy. She had no history of liver disease, alcohol abuse or risk factors for viral hepatitis. She had suffered from Parkinson disease for more than 15 years and was maintained on levodopa and benserazide (25 mg three times daily: a decarboxylase inhibitor similar to carbidopa). Other medications included etilefrine (30 mg daily: an oral adrenergic sympathomimetic amine) for orthostatic hypotension, amiloride (2.5 mg) combined with hydrochlorothiazine (25 mg) twice weekly for edema, and oxazepam (15 mg) at bedtime for sleep, all of these medications having been taken chronically. She had normal liver test results on several occasions in the past while taking these medications. On presentation with jaundice, she was confused and was considered to have stage 2 hepatic encephalopathy. Her resting tremor, akinesia and rigidity were unchanged from before. Laboratory test results showed bilirubin elevations (total 21.5 mg/dL) and marked increases in serum aminotransferase levels (<a class="def" href="/books/n/livertox/glossary/def-item/glossary.alanine-aminotransferase-alt-/">ALT</a> 2904 U/L, <a class="def" href="/books/n/livertox/glossary/def-item/glossary.aspartate-aminotransferase-ast-/">AST</a> 2541 U/L), with minimal abnormality in alkaline phosphatase levels (177 U/L) (Table). The prothrombin time was prolonged (21 seconds; INR 1.7) and ammonia levels were elevated (102 &#x000b5;mol/L). Tests for hepatitis A, B and C were negative and abdominal ultrasound showed no evidence of biliary obstruction or tumor. A transjugular liver biopsy showed large areas of parenchymal collapse that was predominantly centrolobular (zone 3) and accompanied by dense infiltration with chronic inflammatory cells (including eosinophils). There was marked cholestasis, but normal numbers of uninjured bile ducts. There was no fibrosis. The hepatic venous pressure gradient was 7.5 mm Hg (normal &#x0003c;6). Tolcapone was discontinued on admission, but she continued to deteriorate with steadily rising bilirubin levels and worsening consciousness, and she died 13 days later.</p><div id="Tolcapone.Key_Points"><h4>Key Points</h4><div id="Tolcapone.Tc" class="table"><p class="large-table-link" style="display:none"><span class="right"><a href="/books/NBK548573/table/Tolcapone.Tc/?report=objectonly" target="object">View in own window</a></span></p><div class="large_tbl" id="__Tolcapone.Tc_lrgtbl__"><table><tbody><tr><th id="hd_b_Tolcapone.Tc_1_1_1_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">Medication:</th><td headers="hd_b_Tolcapone.Tc_1_1_1_1" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">Tolcapone (200 mg daily)</td></tr><tr><th id="hd_b_Tolcapone.Tc_1_1_2_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">Pattern:</th><td headers="hd_b_Tolcapone.Tc_1_1_2_1" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">Hepatocellular (R=~80)</td></tr><tr><th id="hd_b_Tolcapone.Tc_1_1_3_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">Severity:</th><td headers="hd_b_Tolcapone.Tc_1_1_3_1" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">5+ (death within 2 weeks from acute liver failure)</td></tr><tr><th id="hd_b_Tolcapone.Tc_1_1_4_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"><a class="def" href="/books/n/livertox/glossary/def-item/glossary.latency/">Latency</a>:</th><td headers="hd_b_Tolcapone.Tc_1_1_4_1" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">2 months</td></tr><tr><th id="hd_b_Tolcapone.Tc_1_1_5_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">Recovery:</th><td headers="hd_b_Tolcapone.Tc_1_1_5_1" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">None</td></tr><tr><th id="hd_b_Tolcapone.Tc_1_1_6_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">Other medications:</th><td headers="hd_b_Tolcapone.Tc_1_1_6_1" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">Levodopa, benserazide, etilefrine, amiloride/hydrochlorothiazide, oxazepam</td></tr></tbody></table></div></div></div><div id="Tolcapone.Laboratory_Values"><h4>Laboratory Values</h4><div id="Tolcapone.Td" class="table"><p class="large-table-link" style="display:none"><span class="right"><a href="/books/NBK548573/table/Tolcapone.Td/?report=objectonly" target="object">View in own window</a></span></p><div class="large_tbl" id="__Tolcapone.Td_lrgtbl__"><table class="no_bottom_margin"><thead><tr><th id="hd_h_Tolcapone.Td_1_1_1_1" scope="col" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">Time After<br />Starting</th><th id="hd_h_Tolcapone.Td_1_1_1_2" scope="col" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">Time After<br />Stopping</th><th id="hd_h_Tolcapone.Td_1_1_1_3" scope="col" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;"><a class="def" href="/books/n/livertox/glossary/def-item/glossary.alanine-aminotransferase-alt-/">ALT</a>*<br />(U/L)</th><th id="hd_h_Tolcapone.Td_1_1_1_4" scope="col" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">Alk P<br />(U/L)</th><th id="hd_h_Tolcapone.Td_1_1_1_5" scope="col" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;"><a class="def" href="/books/n/livertox/glossary/def-item/glossary.bilirubin/">Bilirubin</a>*<br />(mg/dL)</th><th id="hd_h_Tolcapone.Td_1_1_1_6" scope="col" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">Other</th></tr></thead><tbody><tr><td headers="hd_h_Tolcapone.Td_1_1_1_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">-1 year</td><td headers="hd_h_Tolcapone.Td_1_1_1_2" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_3" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">21</td><td headers="hd_h_Tolcapone.Td_1_1_1_4" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_5" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_6" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">1 year before starting</td></tr><tr><td headers="hd_h_Tolcapone.Td_1_1_1_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">2 months</td><td headers="hd_h_Tolcapone.Td_1_1_1_2" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">0</td><td headers="hd_h_Tolcapone.Td_1_1_1_3" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">2904</td><td headers="hd_h_Tolcapone.Td_1_1_1_4" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">117</td><td headers="hd_h_Tolcapone.Td_1_1_1_5" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">21.4</td><td headers="hd_h_Tolcapone.Td_1_1_1_6" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">Admission</td></tr><tr><td headers="hd_h_Tolcapone.Td_1_1_1_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_2" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">1 day</td><td headers="hd_h_Tolcapone.Td_1_1_1_3" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">2810</td><td headers="hd_h_Tolcapone.Td_1_1_1_4" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_5" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">24.8</td><td headers="hd_h_Tolcapone.Td_1_1_1_6" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">Liver biopsy</td></tr><tr><td headers="hd_h_Tolcapone.Td_1_1_1_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_2" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">2 days</td><td headers="hd_h_Tolcapone.Td_1_1_1_3" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">2625</td><td headers="hd_h_Tolcapone.Td_1_1_1_4" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_5" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">29.8</td><td headers="hd_h_Tolcapone.Td_1_1_1_6" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">Worsening coma</td></tr><tr><td headers="hd_h_Tolcapone.Td_1_1_1_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_2" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">3 days</td><td headers="hd_h_Tolcapone.Td_1_1_1_3" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">2710</td><td headers="hd_h_Tolcapone.Td_1_1_1_4" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_5" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">39.2</td><td headers="hd_h_Tolcapone.Td_1_1_1_6" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td></tr><tr><td headers="hd_h_Tolcapone.Td_1_1_1_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_2" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">4 days</td><td headers="hd_h_Tolcapone.Td_1_1_1_3" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">2150</td><td headers="hd_h_Tolcapone.Td_1_1_1_4" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_5" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">35.4</td><td headers="hd_h_Tolcapone.Td_1_1_1_6" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td></tr><tr><td headers="hd_h_Tolcapone.Td_1_1_1_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_2" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">5 days</td><td headers="hd_h_Tolcapone.Td_1_1_1_3" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">2275</td><td headers="hd_h_Tolcapone.Td_1_1_1_4" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_5" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">42.4</td><td headers="hd_h_Tolcapone.Td_1_1_1_6" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td></tr><tr><td headers="hd_h_Tolcapone.Td_1_1_1_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_2" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">6 days</td><td headers="hd_h_Tolcapone.Td_1_1_1_3" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">1905</td><td headers="hd_h_Tolcapone.Td_1_1_1_4" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_5" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">35.6</td><td headers="hd_h_Tolcapone.Td_1_1_1_6" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td></tr><tr><td headers="hd_h_Tolcapone.Td_1_1_1_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_2" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">7 days</td><td headers="hd_h_Tolcapone.Td_1_1_1_3" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">1930</td><td headers="hd_h_Tolcapone.Td_1_1_1_4" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_5" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">40.9</td><td headers="hd_h_Tolcapone.Td_1_1_1_6" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td></tr><tr><td headers="hd_h_Tolcapone.Td_1_1_1_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_2" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">8 days</td><td headers="hd_h_Tolcapone.Td_1_1_1_3" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">1783</td><td headers="hd_h_Tolcapone.Td_1_1_1_4" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_5" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td><td headers="hd_h_Tolcapone.Td_1_1_1_6" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td></tr><tr><td headers="hd_h_Tolcapone.Td_1_1_1_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">2.5 months</td><td headers="hd_h_Tolcapone.Td_1_1_1_2" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">2 weeks</td><td headers="hd_h_Tolcapone.Td_1_1_1_3 hd_h_Tolcapone.Td_1_1_1_4 hd_h_Tolcapone.Td_1_1_1_5 hd_h_Tolcapone.Td_1_1_1_6" colspan="4" rowspan="1" style="text-align:left;vertical-align:top;">Patient died of hepatic failure</td></tr><tr><td headers="hd_h_Tolcapone.Td_1_1_1_1 hd_h_Tolcapone.Td_1_1_1_2" colspan="2" scope="row" rowspan="1" style="text-align:center;vertical-align:top;">
<b>Normal Values</b>
</td><td headers="hd_h_Tolcapone.Td_1_1_1_3" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">
<b>&#x0003c;36</b>
</td><td headers="hd_h_Tolcapone.Td_1_1_1_4" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">
<b>&#x0003c;125</b>
</td><td headers="hd_h_Tolcapone.Td_1_1_1_5" rowspan="1" colspan="1" style="text-align:center;vertical-align:top;">
<b>&#x0003c;1.2</b>
</td><td headers="hd_h_Tolcapone.Td_1_1_1_6" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;"></td></tr></tbody></table></div><div><div><dl class="temp-labeled-list small"><dt>* </dt><dd><div id="Tolcapone.TF.d.1"><p class="no_margin">Some values estimated from Figure 2.</p></div></dd></dl></div></div></div></div><div id="Tolcapone.Comment"><h4>Comment</h4><p>This was the first case report in the literature of acute liver failure attributed to tolcapone. The case was published initially as a letter to the editor (Assal: 1998), then as a full case report with details of hepatic histology (Spahr: 2000), and then summarized with 3 other cases of acute liver failure in support of guidelines for monitoring patients on tolcapone (Olanow: 2000). The timing of onset, severe hepatocellular injury and exclusion of other causes of acute liver disease supported the diagnosis of tolcapone induced acute liver injury. Subsequently, routine monitoring for serum enzyme levels during tolcapone therapy was not only recommended, but mandated by the US Food and Drug Administration and no further cases of acute liver failure have been published. However, the concern over hepatotoxicity and the requirement for monitoring has led to a limited use of this medication. Because it appears to be more effective than other COMT inhibitors and can have a beneficial effect in advanced Parkinson disease, it has been reintroduced with strict guidelines for monitoring.</p></div></div></div><div id="Tolcapone.PRODUCT_INFORMATION"><h2 id="_Tolcapone_PRODUCT_INFORMATION_">PRODUCT INFORMATION</h2><p>
<b>REPRESENTATIVE TRADE NAMES</b>
</p><p>Tolcapone &#x02013; Generic, Tasmar&#x000ae;</p><p>
<b>DRUG CLASS</b>
</p><p>Parkinson Disease Agents</p><p>
<a href="https://dailymed.nlm.nih.gov/dailymed/search.cfm?labeltype=all&#x00026;query=Tolcapone" ref="pagearea=body&amp;targetsite=external&amp;targetcat=link&amp;targettype=uri">COMPLETE LABELING</a>
</p><p>Product labeling at DailyMed, National Library of Medicine, NIH</p></div><div id="Tolcapone.CHEMICAL_FORMULA_AND_STRUCTURE"><h2 id="_Tolcapone_CHEMICAL_FORMULA_AND_STRUCTURE_">CHEMICAL FORMULA AND STRUCTURE</h2><div id="Tolcapone.Te" class="table"><p class="large-table-link" style="display:none"><span class="right"><a href="/books/NBK548573/table/Tolcapone.Te/?report=objectonly" target="object">View in own window</a></span></p><div class="large_tbl" id="__Tolcapone.Te_lrgtbl__"><table><thead><tr><th id="hd_h_Tolcapone.Te_1_1_1_1" scope="col" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">DRUG</th><th id="hd_h_Tolcapone.Te_1_1_1_2" scope="col" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">CAS REGISTRY NUMBER</th><th id="hd_h_Tolcapone.Te_1_1_1_3" scope="col" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">MOLECULAR FORMULA</th><th id="hd_h_Tolcapone.Te_1_1_1_4" scope="col" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">STRUCTURE</th></tr></thead><tbody><tr><td headers="hd_h_Tolcapone.Te_1_1_1_1" scope="row" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">Tolcapone</td><td headers="hd_h_Tolcapone.Te_1_1_1_2" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">
<a href="https://pubchem.ncbi.nlm.nih.gov/substance/135029479" ref="pagearea=body&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubchem">134308-13-7</a>
</td><td headers="hd_h_Tolcapone.Te_1_1_1_3" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">C14-H11-N-O5</td><td headers="hd_h_Tolcapone.Te_1_1_1_4" rowspan="1" colspan="1" style="text-align:left;vertical-align:top;">
<a href="https://pubchem.ncbi.nlm.nih.gov/substance/135029479" title="View this structure in PubChem" class="img_link" ref="pagearea=body&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubchem"><img src="https://pubchem.ncbi.nlm.nih.gov/image/imgsrv.fcgi?t=l&amp;sid=135029479" alt="image 135029479 in the ncbi pubchem database" /></a>
</td></tr></tbody></table></div></div></div><div id="Tolcapone.CITED_REFERENCES"><h2 id="_Tolcapone_CITED_REFERENCES_">CITED REFERENCES</h2><dl class="temp-labeled-list"><dt>1.</dt><dd><div class="bk_ref" id="Tolcapone.REF.1">Assal F, Spahr L, Hadengue A, Rubbia-Brandt L, Burkhard PR. Tolcapone and fulminant hepatitis. <span><span class="ref-journal">Lancet. </span>1998;<span class="ref-vol">352</span>:958.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/9752821" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 9752821</span></a>]</div></dd><dt>2.</dt><dd><div class="bk_ref" id="Tolcapone.REF.2">Spahr L, Rubbia-Brandt L, Burkhard PR, Assal F, Hadengue A. Tolcapone-related fulminant hepatitis: electron microscopy shows mitochondrial alterations. <span><span class="ref-journal">Dig Dis Sci. </span>2000;<span class="ref-vol">45</span>:18814.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/11052337" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 11052337</span></a>]</div></dd><dt>3.</dt><dd><div class="bk_ref" id="Tolcapone.REF.3">Olanow CW. Tolcapone and hepatotoxic effects. <span><span class="ref-journal">Tasmar Advisory Panel Arch Neurol. </span>2000;<span class="ref-vol">57</span>:2637.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/10681087" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 10681087</span></a>]</div></dd></dl></div><div id="Tolcapone.ANNOTATED_BIBLIOGRAPHY"><h2 id="_Tolcapone_ANNOTATED_BIBLIOGRAPHY_">ANNOTATED BIBLIOGRAPHY</h2><p>References updated: 25 October 2021</p><p>Abbreviations used: COMT, catechol O-methyltransferase; MAO, monoamine oxidase.</p><ul class="first-line-outdent"><li><div class="bk_ref" id="Tolcapone.REF.zimmerman.1999">Zimmerman HJ. Antiparkinsonism drugs. In, Zimmerman HJ. Hepatotoxicity: the adverse effects of drugs and other chemicals on the liver. 2nd ed. Philadelphia: Lippincott, 1999, pp. 715-7.<div><i>(Expert review of hepatotoxicity published in 1999; among anticholinergic agents, "only trihexyphenidyl has been incriminated in hepatic injury"; other antiparkinsonism drugs discussed include levodopa, lergotrile [no longer available], pergolide and bromocriptine, but not tolcapone).</i></div></div></li><li><div class="bk_ref" id="Tolcapone.REF.larrey.2013">Larrey D, Ripault MP. Hepatotoxicity of psychotropic drugs and drugs of abuse. In, Kaplowitz N, DeLeve LD, eds. Drug-induced liver disease. 3rd ed. Amsterdam: Elsevier Inc, 2013, pp. 443-62.<div><i>(Review of hepatotoxicity of agents acting on the central nervous system).</i></div></div></li><li><div class="bk_ref" id="Tolcapone.REF.roberson.2018">Roberson ED. Parkinson Disease. Treatment of central nervous system degenerative disorders. In, Brunton LL, Hilal-Dandan R, Knollman BC, eds. Goodman &#x00026; Gilman&#x02019;s the pharmacological basis of therapeutics. 13th ed. New York: McGraw-Hill, 2018, pp. 328-333.<div><i>(Textbook of pharmacology and therapeutics; istradefylline and adenosine receptor antagonists are not discussed).</i></div></div></li><li><div class="bk_ref" id="Tolcapone.REF.waters.1998.s39">Waters CH, Kurth M, Bailey P, Shulman LM, LeWitt P, Dorflinger E, Deptula D. S. Tolcapone in stable Parkinson's disease: efficacy and safety of long-term treatment. Tolcapone Stable Study Group. <span><span class="ref-journal">Neurology. </span>1998 May;<span class="ref-vol">50</span>(5) Suppl 5:S3945.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/9591521" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 9591521</span></a>]<div>
<i>(Among 298 patients with stable Parkinson disease treated with levodopa and either tolcapone [n=196] or placebo [n=102], ALT abnormalities occurred in 3-5% of tolcapone treated patients between month 1 and 6 of therapy, 4 were withdrawn and recovered; abnormalities resolved in another 4 despite continuing on therapy).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.hauser.1998.643">Hauser RA, Molho E, Shale H, Pedder S, Dorflinger EE. A pilot evaluation of the tolerability, safety, and efficacy of tolcapone alone and in combination with oral selegiline in untreated Parkinson's disease patients. Tolcapone De Novo Study Group. <span><span class="ref-journal">Mov Disord. </span>1998;<span class="ref-vol">13</span>:6437.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/9686768" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 9686768</span></a>]<div>
<i>(Among 83 patients with Parkinson disease treated with tolcapone with or without selegiline for 8 weeks, ALT elevations occurred in 1 patient [2%] on tolcapone alone).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.tolcapone_for_parkinsons_disease.1998.60">Tolcapone for Parkinson's disease. <span><span class="ref-journal">Med Lett Drugs Ther. </span>1998;<span class="ref-vol">40</span>:601.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/9629124" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 9629124</span></a>]<div>
<i>(Concise summary of clinical efficacy and safety of tolcapone shortly after its approval in the US; common side effects were diarrhea, increase in levodopa related [dopaminergic] side effects and serum ALT elevations).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.assal.1998.958">Assal F, Spahr L, Hadengue A, Rubbia-Brandt L, Burkhard PR. Tolcapone and fulminant hepatitis. <span><span class="ref-journal">Lancet. </span>1998;<span class="ref-vol">352</span>:958.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/9752821" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 9752821</span></a>]<div>
<i>(74 year old woman with Parkinson disease developed jaundice 9 weeks after starting tolcapone [bilirubin 17.1 mg/dL, ALT 2904 U/L, Alk P 177 U/L, protime 21 sec], progressing to hepatic failure and death 2 weeks later).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.rivest.1999.s34">Rivest J, Barclay CL, Suchowersky O. COMT inhibitors in Parkinson's disease. <span><span class="ref-journal">Can J Neurol Sci. </span>1999;<span class="ref-vol">26</span> Suppl 2:S348.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/10451758" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 10451758</span></a>]<div>
<i>(Review of efficacy and safety of tolcapone and entacapone in Parkinson disease; ALT elevations above 3 times the ULN occurred in 2-5% of tolcapone, but in no entacapone recipients; reports of 3 cases of acute liver failure due to tolcapone led to its withdrawal in several countries).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.kaakkola.2000.1233">Kaakkola S. Clinical pharmacology, therapeutic use and potential of COMT inhibitors in Parkinson's disease. <span><span class="ref-journal">Drugs. </span>2000;<span class="ref-vol">59</span>:123350.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/10882160" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 10882160</span></a>]<div>
<i>(Review of the mechanism of action, pharmacology, efficacy and side effects of tolcapone and entacapone; both enhance dopaminergic effects of levodopa and diarrhea is a frequent dose modifying side effect; hepatotoxicity occurs with tolcapone, but has not been reported with entacapone).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.lambert.2000.55">Lambert D, Waters CH. Comparative tolerability of the newer generation antiparkinsonian agents. <span><span class="ref-journal">Drugs Aging. </span>2000;<span class="ref-vol">16</span>:5565.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/10733264" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 10733264</span></a>]<div>
<i>(Review of mechanism of action, tolerability and safety of selegiline, pramipexole, ropinirole, tolcapone and entacapone in Parkinson disease).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.olanow.2000.263">Olanow CW. Tolcapone and hepatotoxic effects. Tasmar Advisory Panel. <span><span class="ref-journal">Arch Neurol. </span>2000;<span class="ref-vol">57</span>:2637.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/10681087" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 10681087</span></a>]<div>
<i>(Consensus recommendations for monitoring patients on tolcapone after 4 reports of acute liver failure; among 1535 patients treated in phase III studies, ALT or AST elevations [&#x0003e;3 times ULN] occurred in 1.3-3.7% of patients, returning to normal when discontinued and one woman developed jaundice and died; postmarketing reports included 4 patients, ages 66 to 74, with onset of symptoms and jaundice after 2-4 months, [bilirubin 6.9-26.1 mg/dL, ALT 1245-5020 U/L, Alk P 66-347 U/L], 3 died within 1-2 weeks of presentation).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.spahr.2000.1881">Spahr L, Rubbia-Brandt L, Burkhard PR, Assal F, Hadengue A. Tolcapone-related fulminant hepatitis: electron microscopy shows mitochondrial alterations. <span><span class="ref-journal">Dig Dis Sci. </span>2000;<span class="ref-vol">45</span>:18814.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/11052337" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 11052337</span></a>]<div>
<i>(Histologic analysis of patient with acute liver failure due to tolcapone [Assal 1988], showed multilobular collapse, inflammatory infiltrates including eosinophils, cholestasis, and focal microvescular steatosis; electron microscopy suggested mitochondrial injury: Case 1).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.watkins.2000.s51">Watkins P. COMT inhibitors and liver toxicity. <span><span class="ref-journal">Neurology. </span>2000;<span class="ref-vol">55</span>(11) Suppl 4:S512.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/11147510" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 11147510</span></a>]<div>
<i>(Review of hepatotoxicity of tolcapone and entacapone suggesting that liver injury is not a class effect and that there have been no reports of jaundice attributed to entacapone).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.entacapone_for_parkinsons_disease.2000.7">Entacapone for Parkinson's disease. <span><span class="ref-journal">Med Lett Drugs Ther. </span>2000;<span class="ref-vol">42</span>:78.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/10696231" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 10696231</span></a>]<div>
<i>(Concise summary of clinical efficacy and safety of entacapone shortly after its approval in the US; common side effects were diarrhea, increase in levodopa related side effects, but no reported hepatotoxicity as occurs with tolcapone).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.blum.2001.158">Blum MW, Siegel AM, Meier R, Hess K. Neuroleptic malignant-like syndrome and acute hepatitis during tolcapone and clozapine medication. <span><span class="ref-journal">Eur Neurol. </span>2001;<span class="ref-vol">46</span>:15860.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/11598337" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 11598337</span></a>]<div>
<i>(70 year old woman developed stupor, rigidity and hyperthermia with increases in CPK [3132 U/L] and ALT [988 U/L], but not bilirubin or alkaline phosphatase while on the combination of tolcapone and clozapine, resolving rapidly on stopping therapy; compatible with neuroleptic malignant-like syndrome).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.myllyl_.2001.53">Myllyl&#x000e4; VV, Kultalahti ER, Haapaniemi H, Leinonen M., FILOMEN Study Group. Twelve-month safety of entacapone in patients with Parkinson's disease. <span><span class="ref-journal">Eur J Neurol. </span>2001;<span class="ref-vol">8</span>:5360.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/11509081" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 11509081</span></a>]<div>
<i>(Among 326 patients with Parkinson disease treated with entacapone or placebo, ALT elevations occurred in 6.9% on drug vs 4.6% on placebo and were above 3 times ULN in 0.9% vs 0.0%; no patient developed clinically apparent liver injury that could be attributed to entacapone).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.acu_a.2002.327">Acu&#x000f1;a G, Foernzler D, Leong D, Rabbia M, Smit R, Dorflinger E, Gasser R, et al. Pharmacogenetic analysis of adverse drug effect reveals genetic variant for susceptibility to liver toxicity. <span><span class="ref-journal">Pharmacogenomics J. </span>2002;<span class="ref-vol">2</span>:32734.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/12439739" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 12439739</span></a>]<div>
<i>(DNA genotyping of 30 single nucleotide polymorphisms in 135 patients who had liver enzyme elevations during tolcapone therapy and controls found variants within the UDP-glucuronsyl transferase gene that were associated with liver injury).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.fisher.2002.1362">Fisher A, Croft-Baker J, Davis M, Purcell P, McLean AJ. Entacapone-induced hepatotoxicity and hepatic dysfunction. <span><span class="ref-journal">Mov Disord. </span>2002;<span class="ref-vol">17</span>:13625.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/12465084" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 12465084</span></a>]<div>
<i>(Three cases of clinically apparent liver injury attributed to entacapone use; 74 year old woman developed nausea and fatigue 2 weeks after adding entacapone to a regimen of levodopa/benserazide for Parkinson disease [bilirubin 2.4 mg/dL, ALT 104 U/L, Alk P 238 U/L], with rapid improvement on stopping; 2 other cases were reported to Australian Drug Reaction Database with only partial documentation, arising 5 and 6 weeks after starting entacapone, with cholestatic liver enzyme elevations and mild jaundice).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.benabou.2003.263">Benabou R, Waters C. Hepatotoxic profile of catechol-O-methyltransferase inhibitors in Parkinson's disease. <span><span class="ref-journal">Expert Opin Drug Saf. </span>2003;<span class="ref-vol">2</span>:2637.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/12904105" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 12904105</span></a>]<div>
<i>(Review of hepatotoxicity of tolcapone and entacapone).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.borges.2003.743">Borges N. Tolcapone-related liver dysfunction: implications for use in Parkinson's disease therapy. <span><span class="ref-journal">Drug Saf. </span>2003;<span class="ref-vol">26</span>:7437.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/12908845" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 12908845</span></a>]<div>
<i>(Review of hepatotoxicity of tolcapone and possible mechanisms).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.brooks.2004.s39">Brooks DJ. Safety and tolerability of COMT inhibitors. <span><span class="ref-journal">Neurology. </span>2004;<span class="ref-vol">62</span>(1) Suppl 1:S3946.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/14718679" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 14718679</span></a>]<div>
<i>(Review of safety and side effects of entacapone; in phase III trials ALT elevations &#x0003e;3 times ULN occurred in 0.3-0.5% of patients taking entacapone and 0.4% on placebo, and there were no cases of jaundice or clinically apparent liver injury among ~1600 entacapone treated patients).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.deane.2004.cd004554">Deane KH, Spieker S, Clarke CE. Catechol-O-methyltransferase inhibitors for levodopa-induced complications in Parkinson's disease. <span><span class="ref-journal">Cochrane Database Syst Rev. </span>2004;(4):CD004554. </span> [<a href="/pmc/articles/PMC8830033/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC8830033</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/15495119" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 15495119</span></a>]<div>
<i>(Systematic review of efficacy of tolcapone and entacapone; ALT elevations reported in variable proportions of patients on tolcapone).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF26">Levodopa + carbidopa + entacapone. Entacapone: a second look: new preparations. Parkinson's disease: a modest effect. <span><span class="ref-journal">Prescrire Int. </span>2005;<span class="ref-vol">14</span>:514.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/15875340" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 15875340</span></a>]<div>
<i>(Review of risks and benefits of a fixed dose combination of levodopa, carbidopa and entacapone mentions that entacapone may cause cholestatic hepatitis and that is has not been shown to be more effective than bromocriptine).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.borges.2005.69">Borges N. Tolcapone in Parkinson's disease: liver toxicity and clinical efficacy. <span><span class="ref-journal">Expert Opin Drug Saf. </span>2005;<span class="ref-vol">4</span>:6973.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/15709899" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 15709899</span></a>]<div>
<i>(Review of hepatotoxicity of tolcapone and its possible mechanisms).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.korri.2005.1113">Korri H, Awada A. <span><span class="ref-journal">Rev Neurol (Paris). </span>2005;<span class="ref-vol">161</span>:11135.</span> [Serious tolcapone-induced hepatitis 17 months after commencing treatment] French. [<a href="https://pubmed.ncbi.nlm.nih.gov/16288178" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 16288178</span></a>]<div>
<i>(61 year old man with Parkinson disease developed jaundice and fever 17 months after starting tolcapone [bilirubin 3.1 mg/dL, ALT 399 U/L, Alk P 115 U/L], resolving upon stopping).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.martignoni.2005.1820">Martignoni E, Cosentino M, Ferrari M, Porta G, Mattarucchi E, Marino F, Lecchini S, et al. Two patients with COMT inhibitor-induced hepatic dysfunction and UGT1A9 genetic polymorphism. <span><span class="ref-journal">Neurology. </span>2005;<span class="ref-vol">65</span>:18202.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/16344532" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 16344532</span></a>]<div>
<i>(Two patients who had ALT elevations [78 and 284 U/L] during tolcapone therapy, one of whom had similar elevations during entacapone treatment; both had the A(T)9AT sequence [1A9*1] in the promoter of the UGT1A9 gene).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF30">Tolcapone: new drug. In Parkinson's disease: unacceptable risk of severe hepatitis. <span><span class="ref-journal">Prescrire Int. </span>2006;<span class="ref-vol">15</span>:547.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/16604736" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 16604736</span></a>]<div>
<i>(Review of tolcapone as adjunctive therapy in Parkinson disease suggests that the hepatotoxicity risk makes it an unacceptable option).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.leegwaterkim.2006.2263">Leegwater-Kim J, Waters C. Tolcapone in the management of Parkinson's disease. <span><span class="ref-journal">Expert Opin Pharmacother. </span>2006;<span class="ref-vol">7</span>:226370.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/17059382" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 17059382</span></a>]<div>
<i>(Review on use of tolcapone in Parkinson disease suggesting that with proper monitoring, the potential for hepatotoxicity is "negligibly small").</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.stocchi.2006.317">Stocchi F, De Pandis MF. Utility of tolcapone in fluctuating Parkinson's disease. <span><span class="ref-journal">Clin Interv Aging. </span>2006;<span class="ref-vol">1</span>:31725.</span> [<a href="/pmc/articles/PMC2699640/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC2699640</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/18046910" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 18046910</span></a>]<div>
<i>(Review of role of tolcapone in treatment of Parkinson disease, indicating its efficacy in patients with fluctuating symptoms and its safety with proper monitoring of serum enzymes).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.entacapone_to_tolcapone_switch_study_investigators.2007.14">Entacapone to Tolcapone Switch Study Investigators. Entacapone to tolcapone switch: Multicenter double-blind, randomized, active-controlled trial in advanced Parkinson's disease. <span><span class="ref-journal">Mov Disord. </span>2007;<span class="ref-vol">22</span>:149.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/17089403" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 17089403</span></a>]<div>
<i>(Randomized controlled trial of replacing entacapone with tolcapone in patients with Parkinson disease and motor fluctuations on long term levodopa therapy; ALT elevations occurred in 3% on entacapone and 9% on tolcapone, but were mild and self-limiting).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.leegwaterkim.2007.1649">Leegwater-Kim J, Waters C. Role of tolcapone in the treatment of Parkinson's disease. <span><span class="ref-journal">Expert Rev Neurother. </span>2007;<span class="ref-vol">7</span>:164957.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/18052761" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 18052761</span></a>]<div>
<i>(Review of the pharmacology, metabolism, clinical efficacy and safety of tolcapone, indicating that the risk of hepatotoxicity "is very small if proper hepatic monitoring guidelines are followed").</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.olanow.2007.287">Olanow CW, Watkins PB. Tolcapone: an efficacy and safety review (2007). <span><span class="ref-journal">Clin Neuropharmacol. </span>2007;<span class="ref-vol">30</span>:28794.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/17909307" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 17909307</span></a>]<div>
<i>(Review of the efficacy and safety of tolcapone focusing upon the hepatotoxicity concludes that tolcapone can be used safety if there is strict adherence to routine liver test monitoring requirements of every 2-4 weeks for 6 months and at 3-6 month intervals thereafter).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.lees.2007.944">Lees AJ, Ratziu V, Tolosa E, Oertel WH. Safety and tolerability of adjunctive tolcapone treatment in patients with early Parkinson's disease. <span><span class="ref-journal">J Neurol Neurosurg Psychiatry. </span>2007;<span class="ref-vol">78</span>:9448.</span> [<a href="/pmc/articles/PMC2117861/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC2117861</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/17098835" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 17098835</span></a>]<div>
<i>(Controlled trial of tolcapone vs placebo combined with levodopa and carbidopa in 677 patients with early Parkinson disease; ALT or AST elevations occurred in 20% of placebo- vs 27% of tolcapone treated patients and were &#x0003e;3 times ULN in 1.2% [placebo] vs 1.8% [tolcapone], almost all during first 6 months; 1% of tolcapone treated patients stopped because of ALT elevations, but none developed jaundice or clinically apparent liver injury).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.lew.2007.281">Lew MF, Kricorian G. Results from a 2-year centralized tolcapone liver enzyme monitoring program. <span><span class="ref-journal">Clin Neuropharmacol. </span>2007;<span class="ref-vol">30</span>:2816.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/17909306" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 17909306</span></a>]<div>
<i>(Centralized testing for ALT and AST in 1725 patients with Parkinson disease treated with tolcapone for up to 2 years; 69 [3.9%] had at least one elevation, but &#x0003c;1% had an elevation above 2 times the ULN and most returned to normal despite continuing therapy).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF38">Entacapone: hepatitis (continued). The risk of liver damage is being confirmed. It is better not to expose parkinsonian patients to this drug. <span><span class="ref-journal">Prescrire Int. </span>2008;<span class="ref-vol">17</span>:1134.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/18630358" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 18630358</span></a>]<div>
<i>(Commentary mentions that the European Medicines Agency has reported 29 cases of hepatic disorders linked to entacapone).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.chalasani.2008.1924">Chalasani N, Fontana RJ, Bonkovsky HL, Watkins PB, Davern T, Serrano J, Yang H, Rochon J., Drug Induced Liver Injury Network (DILIN). Causes, clinical features, and outcomes from a prospective study of drug-induced liver injury in the United States. <span><span class="ref-journal">Gastroenterology. </span>2008;<span class="ref-vol">135</span>:192434.</span> [<a href="/pmc/articles/PMC3654244/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC3654244</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/18955056" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 18955056</span></a>]<div>
<i>(Among 300 cases of drug induced liver injury in the US collected between 2004 and 2008, none were due to drugs used for Parkinson disease).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.canesi.2008.s380">Canesi M, Zecchinelli AL, Pezzoli G, Antonini A. Clinical experience of tolcapone in advanced Parkinson's disease. <span><span class="ref-journal">Neurol Sci. </span>2008;<span class="ref-vol">29</span> Suppl 5:S3802.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/19381768" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 19381768</span></a>]<div>
<i>(Among 66 patients with advanced Parkinson disease treated with tolcapone, 2 [3%] were withdrawn from therapy because of ALT elevations).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.brooks.2008.843">Brooks DJ, Leinonen M, Kuoppam&#x000e4;ki M, Nissinen H. Five-year efficacy and safety of levodopa/DDCI and entacapone in patients with Parkinson's disease. <span><span class="ref-journal">J Neural Transm. </span>2008;<span class="ref-vol">115</span>:8439.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/18259682" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 18259682</span></a>]<div>
<i>(Retrospective, pooled analysis of 5 controlled trials with 5 year extension phases that included 806 patients with Parkinson disease treated with entacapone added to levodopa/carbodopa; there were "few clinically significant changes in liver function tests" and none of the 478 serious adverse events that were reported were due to hepatotoxicity).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.ebersbach.2009.e40">Ebersbach G, Storch A. Tolcapone in elderly patients with Parkinson's disease: a prospective open-label multicenter non-interventional trial. <span><span class="ref-journal">Arch Gerontol Geriatr. </span>2009;<span class="ref-vol">49</span>:e404.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/18835049" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 18835049</span></a>]<div>
<i>(Among 237 patients with advanced Parkinson disease treated with tolcapone, diarrhea was the most common side effect [3.4%], ALT or AST elevations occurred in 18%, but were mostly mild and "not clinically significant").</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.mcburney.2009.52">McBurney RN, Hines WM, Von Tungeln LS, Schnackenberg LK, Beger RD, Moland CL, Han T, et al. The liver toxicity biomarker study: phase I design and preliminary results. <span><span class="ref-journal">Toxicol Pathol. </span>2009;<span class="ref-vol">37</span>:5264.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/19171931" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 19171931</span></a>]<div>
<i>(Design and early results of a comprehensive study of rats given 28 days of entacapone or tolcapone as examples of two related agents, one of which causes liver injury in man and one which does not, assessing liver enzymes, histology, gene transcription, proteomics, metabolomics and possible biomarkers to identify predictors of idiosyncratic liver injury in humans).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.reuben.2010.2065">Reuben A, Koch DG, Lee WM., Acute Liver Failure Study Group. Drug-induced acute liver failure: results of a U.S. multicenter, prospective study. <span><span class="ref-journal">Hepatology. </span>2010;<span class="ref-vol">52</span>:206576.</span> [<a href="/pmc/articles/PMC3992250/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC3992250</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/20949552" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 20949552</span></a>]<div>
<i>(Among 1198 patients with acute liver failure enrolled in a US prospective study between 1998 and 2007, 133 were attributed to drug induced liver injury but none were attributed to agents used for Parkinson disease).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.fischer.2010.243">Fischer JJ, Michaelis S, Schrey AK, Graebner OG, Glinski M, Dreger M, Kroll F, et al. Capture compound mass spectrometry sheds light on the molecular mechanisms of liver toxicity of two Parkinson drugs. <span><span class="ref-journal">Toxicol Sci. </span>2010;<span class="ref-vol">113</span>:24353.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/19783845" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 19783845</span></a>]<div>
<i>(In vitro study of binding of tolcapone and entacapone to other proteins; unlike entacapone, tolcapone interacted with a number of non-COMT intracellular proteins which are involved in the respiratory chain actions, fatty acid beta-oxidation and bile acid synthesis, perhaps accounting for its potential for hepatotoxicity).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.haasio.2010.163">Haasio K. Toxicology and safety of COMT inhibitors. <span><span class="ref-journal">Int Rev Neurobiol. </span>2010;<span class="ref-vol">95</span>:16389.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/21095462" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 21095462</span></a>]<div>
<i>(Extensive review of the mechanism of hepatic injury from tolcapone; "at the moment there is no explanation to the hepatotoxicity appeared in clinical use").</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.marsala.2012.185">Marsala SZ, Gioulis M, Ceravolo R, Tinazzi M. A systematic review of catechol-0-methyltransferase inhibitors: efficacy and safety in clinical practice. <span><span class="ref-journal">Clin Neuropharmacol. </span>2012;<span class="ref-vol">35</span>:18590.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/22805229" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 22805229</span></a>]<div>
<i>(Systematic review of literature on safety and efficacy of tolcapone and entacapone recommends use of tolcapone only if entacapone treatment fails and liver tests are normal).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.mcburney.2012.951">McBurney RN, Hines WM, VonTungeln LS, Schnackenberg LK, Beger RD, Moland CL, Han T, et al. The liver toxicity biomarker study phase I: markers for the effects of tolcapone or entacapone. <span><span class="ref-journal">Toxicol Pathol. </span>2012;<span class="ref-vol">40</span>:95164.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/22573522" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 22573522</span></a>]<div>
<i>(Comparison of the molecular effects of tolcapone vs entacapone on rat liver and plasma biomarkers found that changes from the two drugs only partially overlapped and different effects were present at 3 and 28 days, suggesting that some of these "off-target" and specific effects of tolcapone may account for its occasional hepatotoxicity).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.bj_rnsson.2013.1419">Bj&#x000f6;rnsson ES, Bergmann OM, Bj&#x000f6;rnsson HK, Kvaran RB, Olafsson S. Incidence, presentation, and outcomes in patients with drug-induced liver injury in the general population of Iceland. <span><span class="ref-journal">Gastroenterology. </span>2013;<span class="ref-vol">144</span>:14191425.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/23419359" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 23419359</span></a>]<div>
<i>(In a population based study of drug induced liver injury from Iceland, 96 cases were identified over a 2 year period, but none of the 96 were attributed to an agent used to treat Parkinson disease).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.drugs_for_parkinsons_disease.2013.101">Drugs for Parkinson's disease. <span><span class="ref-journal">Treat Guidel Med Lett. </span>2013;<span class="ref-vol">11</span>(135):1016.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/24165688" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 24165688</span></a>]<div>
<i>(Concise review of recommendations for therapy of Parkinson disease with description of mechanisms of action, efficacy and adverse events).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.hern_ndez.2014.231">Hern&#x000e1;ndez N, Bessone F, S&#x000e1;nchez A, di Pace M, Brahm J, Zapata R, A, Chirino R, et al. Profile of idiosyncratic drug induced liver injury in Latin America: an analysis of published reports. <span><span class="ref-journal">Ann Hepatol. </span>2014;<span class="ref-vol">13</span>:2319.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/24552865" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 24552865</span></a>]<div>
<i>(Among 176 reports of drug induced liver injury from Latin America published between 1996 and 2012, none were attributed to an agent to treat Parkinson disease).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.eggert.2014.1">Eggert K, Oertel WH, Lees AJ. German Competence Network on Parkinson&#x02019;s disease. Safety and efficacy of tolcapone in the long-term use in Parkinson disease: an observational study. <span><span class="ref-journal">Clin Neuropharmacol. </span>2014;<span class="ref-vol">37</span>:15.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/24434524" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 24434524</span></a>]<div>
<i>(Among 391 patients with Parkinson disease treated with tolcapone in an observation study conducted at 48 neurologic centers and followed for one year, 34 [8.7%] developed liver enzyme elevation, usually within the first 3 months, which were above twice ULN in only 5 [1.3%] and resolved spontaneously in most; no patient developed clinically apparent liver injury).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.chalasani.2015.1340">Chalasani N, Bonkovsky HL, Fontana R, Lee W, Stolz A, Talwalkar J, Reddy KR, et al. United States Drug Induced Liver Injury Network. Features and outcomes of 899 patients with drug-induced liver injury: The DILIN Prospective Study. <span><span class="ref-journal">Gastroenterology. </span>2015;<span class="ref-vol">148</span>:134052.e7.</span> [<a href="/pmc/articles/PMC4446235/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC4446235</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/25754159" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 25754159</span></a>]<div>
<i>(Among 899 cases of drug induced liver injury from the US enrolled in a prospective database between 2004 and 2012, none were attributed to an agent used to treat Parkinson disease).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.longo.2016.31">Longo DM, Yang Y, Watkins PB, Howell BA, Siler SQ. Elucidating differences in the hepatotoxic potential of tolcapone and entacapone with DILIsym(&#x000ae;), a mechanistic model of drug-induced liver injury. <span><span class="ref-journal">CPT Pharmacometrics Syst Pharmacol. </span>2016;<span class="ref-vol">5</span>(1):319.</span> [<a href="/pmc/articles/PMC4728295/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC4728295</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/26844013" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 26844013</span></a>]<div>
<i>(Description of mechanistic simulation models of the metabolism and toxicity of tolcapone and entacapone which predicted their differential hepatotoxicity).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.lv.2016.42">Lv X, Wang XX, Hou J, Fang ZZ, Wu JJ, Cao YF, Liu SW, et al. Comparison of the inhibitory effects of tolcapone and entacapone against human UDP-glucuronosyl-transferases. <span><span class="ref-journal">Toxicol Appl Pharmacol. </span>2016;<span class="ref-vol">301</span>:429.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/27089846" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 27089846</span></a>]<div>
<i>(Comparison of the inhibitory effects of tolacapone and entacapone against recombinant human UGTs showed more potent inhibition by tolacapone for most isoforms).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.drugs_for_parkinsons_disease.2017.187">Drugs for Parkinson's disease. <span><span class="ref-journal">Med Lett Drugs Ther. </span>2017;<span class="ref-vol">59</span>(1534):187194.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/29136401" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 29136401</span></a>]<div>
<i>(Concise review of medications approved for use in Parkinson disease including levodopa/carbidopa, dopamine agonists, MAO-B inhibitors, anticholinergics, and COMT inhibitors, mentions hepatotoxicity of tolcapone but not of levodopa or any of the other adjunctive therapies: &#x0201c;Use of tolcapone requires written informed consent and monitoring of liver function every 2-4 weeks for the first 6 months of treatment and periodically thereafter. Serious hepatoxicity has not been reported with entacapone&#x0201d;).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.margolesky.2017.1756285617737728">Margolesky J, Singer C. Extended-release oral capsule of carbidopa-levodopa in Parkinson disease. <span><span class="ref-journal">Ther Adv Neurol Disord. </span>2017;<span class="ref-vol">11</span>:1756285617737728. </span> [<a href="/pmc/articles/PMC5784558/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC5784558</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/29399046" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 29399046</span></a>]<div>
<i>(Review of the pharmacology, efficacy and safety of extended release carbidopa/levodopa in listing of reported adverse reactions there is no mention of serious hepatic events or ALT elevations).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.mak.2018.412">Mak A, Kato R, Weston K, Hayes A, Uetrecht J. Editor's highlight: An impaired immune tolerance animal model distinguishes the potential of troglitazone/pioglitazone and tolcapone/entacapone to cause IDILI. <span><span class="ref-journal">Toxicol Sci. </span>2018;<span class="ref-vol">161</span>:412420.</span> [<a href="/pmc/articles/PMC5837423/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC5837423</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/29087505" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 29087505</span></a>]<div>
<i>(In an animal model of idiosyncratic liver injury using PD-1 knock out mice treated with anti-CTLA-4 to decrease the natural inhibition of T cell responses [immune check point], treatment with tolcapone caused greater injury than treatment with entacapone while neither agent caused liver injury in wild type mice or PD-1 knock out mice without anti-CTLA-4 treatment, suggesting that idiosyncratic liver injury is immune mediated, caused by an unregulated CD-8+ response and failure of immune tolerance).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.fremont.2020.1391">Fremont R, Manoochehri M, Armstrong NM, Mattay VS, Apud JA, Tierney MC, Devanand DP, et al. Tolcapone treatment for cognitive and behavioral symptoms in behavioral variant frontotemporal dementia: a placebo-controlled crossover study. <span><span class="ref-journal">J Alzheimers Dis. </span>2020;<span class="ref-vol">75</span>:13911403.</span> [<a href="/pmc/articles/PMC10131251/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC10131251</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/32444540" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 32444540</span></a>]<div>
<i>(Among 28 adults with frontotemporal dementia with behavioral symptoms who were treated with tolcapone [200 mg] or placebo three times daily for 9 days in a cross-over design, tolcapone therapy was associated with slight improvements in some cognitive and behavioral scores and was well tolerated, although 21% of patients developed mild liver enzyme elevations [less than twice ULN] that were asymptomatic and resolved rapidly).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.artusi.2021.817">Artusi CA, Sarro L, Imbalzano G, Fabbri M, Lopiano L. Safety and efficacy of tolcapone in Parkinson's disease: systematic review. <span><span class="ref-journal">Eur J Clin Pharmacol. </span>2021;<span class="ref-vol">77</span>:817829.</span> [<a href="/pmc/articles/PMC8128808/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC8128808</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/33415500" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 33415500</span></a>]<div>
<i>(Systematic review of the literature on the efficacy and safety of tolcapone identified 32 studies with 4780 patients, of whom 0.9% developed liver enzyme elevations above 2 times ULN; and while there were 3 case reports of fatal acute liver failure all reported in 1998, since then there have been no deaths and only 3 non-fatal cases).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.drugs_for_parkinsons_disease.2021.25">Drugs for Parkinson's disease. <span><span class="ref-journal">Med Lett Drugs Ther. </span>2021;<span class="ref-vol">63</span>(1618):2532.</span> [<a href="https://pubmed.ncbi.nlm.nih.gov/33647001" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 33647001</span></a>]<div>
<i>(Concise review of current medications approved for use in Parkinson disease including levodopa/carbidopa, dopamine agonists, COMT inhibitors, MAO-B inhibitors, anticholinergics, and istradefylline, mentions hepatotoxicity of tolcapone but not of levodopa or any of the adjunctive therapies).</i>
</div></div></li><li><div class="bk_ref" id="Tolcapone.REF.hauser.2021.1663">Hauser RA, Hattori N, Fernandez H, Isaacson SH, Mochizuki H, Rascol O, Stocchi F, et al. Efficacy of istradefylline, an adenosine A2A receptor antagonist, as adjunctive therapy to levodopa in Parkinson's disease: a pooled analysis of 8 phase 2b/3 trials. <span><span class="ref-journal">J Parkinsons Dis. </span>2021;<span class="ref-vol">11</span>:166375.</span> [<a href="/pmc/articles/PMC8609697/" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pmc">PMC free article<span class="bk_prnt">: PMC8609697</span></a>] [<a href="https://pubmed.ncbi.nlm.nih.gov/34486986" ref="pagearea=cite-ref&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">PubMed<span class="bk_prnt">: 34486986</span></a>]<div>
<i>(In a pooled analysis of 8 randomized placebo-controlled trials of istradefylline in 2719 patients with Parkinson disease and motor complications, while adverse event rates were similar in the 3 groups [71% and 70% vs 65%] except for dyskinesia [16% and 18% vs 10%] and &#x0201c;no clinically meaningful changes in laboratory parameters&#x02026;were observed&#x0201d; in any group including those on levodopa/carbidopa alone).</i>
</div></div></li></ul></div><div id="bk_toc_contnr"></div></div></div>
<div class="post-content"><div><div class="half_rhythm"><a href="/books/about/copyright/">Copyright Notice</a></div><div class="small"><span class="label">Bookshelf ID: NBK548573</span><span class="label">PMID: <a href="https://pubmed.ncbi.nlm.nih.gov/31643888" title="PubMed record of this page" ref="pagearea=meta&amp;targetsite=entrez&amp;targetcat=link&amp;targettype=pubmed">31643888</a></span></div><div style="margin-top:2em" class="bk_noprnt"><a class="bk_cntns" href="/books/n/livertox/">Drug Records</a><div class="pagination bk_noprnt"><a class="active page_link prev" href="/books/n/livertox/Tofacitinib/" title="Previous page in this title">&lt; Prev</a><a class="active page_link next" href="/books/n/livertox/Tolmetin/" title="Next page in this title">Next &gt;</a></div></div></div></div>
</div>
<!-- Custom content below content -->
<div class="col4">
</div>
<!-- Book content -->
<!-- Custom contetnt below bottom nav -->
<div class="col5">
</div>
</div>
<div id="rightcolumn" class="four_col col last">
<!-- Custom content above discovery portlets -->
<div class="col6">
<div id="ncbi_share_book"><a href="#" class="ncbi_share" data-ncbi_share_config="popup:false,shorten:true" ref="id=NBK548573&amp;db=books">Share</a></div>
</div>
<div xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>Views</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="PDF_download" id="Shutter"></a></div><div class="portlet_content"><ul xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="simple-list"><li><a href="/books/NBK548573/?report=reader">PubReader</a></li><li><a href="/books/NBK548573/?report=printable">Print View</a></li><li><a data-jig="ncbidialog" href="#_ncbi_dlg_citbx_NBK548573" data-jigconfig="width:400,modal:true">Cite this Page</a><div id="_ncbi_dlg_citbx_NBK548573" style="display:none" title="Cite this Page"><div class="bk_tt">LiverTox: Clinical and Research Information on Drug-Induced Liver Injury [Internet]. Bethesda (MD): National Institute of Diabetes and Digestive and Kidney Diseases; 2012-. Tolcapone. [Updated 2021 Oct 25].<span class="bk_cite_avail"></span></div></div></li><li><a href="/books/NBK548573/pdf/Bookshelf_NBK548573.pdf">PDF version of this page</a> (173K)</li><li><a href="#" class="toggle-glossary-link" title="Enable/disable links to the glossary">Disable Glossary Links</a></li></ul></div></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>New and Updated</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="source-links" id="Shutter"></a></div><div class="portlet_content"><ul xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="simple-list"><li><a href="https://pubmed.ncbi.nlm.nih.gov/?term=%22LiverTox%22+AND+pmcbook&amp;sort=date&amp;size=200" ref="pagearea=source-links&amp;targetsite=external&amp;targetcat=link&amp;targettype=uri">In PubMed</a></li></ul></div></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>Bulk Download</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="source-links" id="Shutter"></a></div><div class="portlet_content"><ul xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="simple-list"><li><a href="https://ftp.ncbi.nlm.nih.gov/pub/litarch/29/31/" ref="pagearea=source-links&amp;targetsite=external&amp;targetcat=link&amp;targettype=uri">Bulk download LiverTox data from FTP</a></li></ul></div></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>Overviews</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="source-links" id="Shutter"></a></div><div class="portlet_content"><ul xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="simple-list"><li><a href="/books/n/livertox/intro/">Introduction</a></li><li><a href="/books/n/livertox/ClinicalCourse/">Clinical Course</a></li><li><a href="/books/n/livertox/ClinicalOutcome/">Clinical Outcomes</a></li><li><a href="/books/n/livertox/ImmuneFeatures/">Immune Features</a></li><li><a href="/books/n/livertox/Phenotypes_intro/">Phenotypes</a></li><li><a href="/books/n/livertox/Causality/">Causality</a></li><li><a href="/books/n/livertox/DrugCategory/">Likelihood Scale</a></li><li><a href="/books/n/livertox/Severity/">Severity Grading</a></li><li><a href="/books/n/livertox/CaseReport/">Writing a Case Report</a></li></ul></div></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>Support Links</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="source-links" id="Shutter"></a></div><div class="portlet_content"><ul xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="simple-list"><li><a href="/books/n/livertox/">LiverTox Homepage</a></li><li><a href="/books/n/livertox/masterlistintro/">Master List of LiverTox Drugs [with Metadata]</a></li><li><a href="/books/n/livertox/drugliverinjury/">LiverTox Drugs by Drug Class</a></li><li><a href="/books/n/livertox/aboutus/">About LiverTox</a></li><li><a href="/books/n/livertox/editorsandreviewers/">Editors and Review Committee</a></li><li><a href="/books/n/livertox/alert/">Meetings and News</a></li><li><a href="/books/n/livertox/abbreviation/">Abbreviations Used</a></li><li><a href="/books/n/livertox/glossary/">Glossary</a></li><li><a href="/books/n/livertox/resource/">Information Resources</a></li><li><a href="/books/n/livertox/disclaimer/">User/Medical Advice Disclaimer</a></li><li><a href="/books/n/livertox/Contactus/">Contact Us</a></li></ul></div></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>OTHER REFERENCE LINKS</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="document-links" id="Shutter"></a></div><div class="portlet_content"><ul xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="simple-list"><li>
<a href="https://www.ncbi.nlm.nih.gov/sites/entrez?cmd=search&amp;db=pubmed&amp;pubmedfilters=true&amp;term=(Tolcapone/AE)+AND+Human%5BMH%5D+AND+(drug+induced+liver+injury+OR+jaundice/CI+OR+bile+duct+diseases/CI+OR+liver/DE+OR+liver+diseases/CI)+AND+(%221900/1/1%22%5BEDat%5D:%222999/12/31%22%5BEDat%5D)" ref="pagearea=document-links&amp;targetsite=external&amp;targetcat=link&amp;targettype=uri">Recent References on Tolcapone: from PubMed.gov</a>
</li><li>
<a href="https://clinicaltrials.gov/ct2/results?term=Tolcapone" ref="pagearea=document-links&amp;targetsite=external&amp;targetcat=link&amp;targettype=uri">Trials on Tolcapone: from ClinicalTrials.gov</a>
</li></ul></div></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>Related information</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="discovery_db_links" id="Shutter"></a></div><div class="portlet_content"><ul><li class="brieflinkpopper"><a class="brieflinkpopperctrl" href="/books/?Db=pmc&amp;DbFrom=books&amp;Cmd=Link&amp;LinkName=books_pmc_refs&amp;IdsFromResult=4861980" ref="log$=recordlinks">PMC</a><div class="brieflinkpop offscreen_noflow">PubMed Central citations</div></li><li class="brieflinkpopper"><a class="brieflinkpopperctrl" href="/books/?Db=pcsubstance&amp;DbFrom=books&amp;Cmd=Link&amp;LinkName=books_pcsubstance&amp;IdsFromResult=4861980" ref="log$=recordlinks">PubChem Substance</a><div class="brieflinkpop offscreen_noflow">Related PubChem Substances</div></li><li class="brieflinkpopper"><a class="brieflinkpopperctrl" href="/books/?Db=pubmed&amp;DbFrom=books&amp;Cmd=Link&amp;LinkName=books_pubmed_refs&amp;IdsFromResult=4861980" ref="log$=recordlinks">PubMed</a><div class="brieflinkpop offscreen_noflow">Links to PubMed</div></li></ul></div></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>Similar articles in PubMed</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="PBooksDiscovery_RA" id="Shutter"></a></div><div class="portlet_content"><ul><li class="brieflinkpopper two_line"><a class="brieflinkpopperctrl" href="/pubmed/8255478" ref="ordinalpos=1&amp;linkpos=1&amp;log$=relatedarticles&amp;logdbfrom=pubmed">Catechol-O-methyltransferase inhibitor tolcapone prolongs levodopa/carbidopa action in parkinsonian patients.</a><span class="source">[Neurology. 1993]</span><div class="brieflinkpop offscreen_noflow">Catechol-O-methyltransferase inhibitor tolcapone prolongs levodopa/carbidopa action in parkinsonian patients.<div class="brieflinkpopdesc"><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="author">Roberts JW, Cora-Locatelli G, Bravi D, Amantea MA, Mouradian MM, Chase TN. </em><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="cit">Neurology. 1993 Dec; 43(12):2685-8. </em></div></div></li><li class="brieflinkpopper two_line"><a class="brieflinkpopperctrl" href="/pubmed/24770794" ref="ordinalpos=1&amp;linkpos=2&amp;log$=relatedarticles&amp;logdbfrom=pubmed">Fewer fluctuations, higher maximum concentration and better motor response of levodopa with catechol-O-methyltransferase inhibition.</a><span class="source">[J Neural Transm (Vienna). 2014]</span><div class="brieflinkpop offscreen_noflow">Fewer fluctuations, higher maximum concentration and better motor response of levodopa with catechol-O-methyltransferase inhibition.<div class="brieflinkpopdesc"><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="author">Muhlack S, Herrmann L, Salmen S, Müller T. </em><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="cit">J Neural Transm (Vienna). 2014 Nov; 121(11):1357-66. Epub 2014 Apr 26.</em></div></div></li><li class="brieflinkpopper two_line"><a class="brieflinkpopperctrl" href="/pubmed/10510160" ref="ordinalpos=1&amp;linkpos=3&amp;log$=relatedarticles&amp;logdbfrom=pubmed">COMT inhibition with tolcapone does not affect carbidopa pharmacokinetics in parkinsonian patients in levodopa/carbidopa (Sinemet).</a><span class="source">[Br J Clin Pharmacol. 1999]</span><div class="brieflinkpop offscreen_noflow">COMT inhibition with tolcapone does not affect carbidopa pharmacokinetics in parkinsonian patients in levodopa/carbidopa (Sinemet).<div class="brieflinkpopdesc"><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="author">Jorga KM, Nicholl DJ. </em><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="cit">Br J Clin Pharmacol. 1999 Sep; 48(3):449-52. </em></div></div></li><li class="brieflinkpopper two_line"><a class="brieflinkpopperctrl" href="/pubmed/9917075" ref="ordinalpos=1&amp;linkpos=4&amp;log$=relatedreviews&amp;logdbfrom=pubmed"><span xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="invert">Review</span> Tolcapone, a selective catechol-O-methyltransferase inhibitor for treatment of Parkinson's disease.</a><span class="source">[Pharmacotherapy. 1999]</span><div class="brieflinkpop offscreen_noflow"><span xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="invert">Review</span> Tolcapone, a selective catechol-O-methyltransferase inhibitor for treatment of Parkinson's disease.<div class="brieflinkpopdesc"><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="author">Guay DR. </em><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="cit">Pharmacotherapy. 1999 Jan; 19(1):6-20. </em></div></div></li><li class="brieflinkpopper two_line"><a class="brieflinkpopperctrl" href="/pubmed/10882160" ref="ordinalpos=1&amp;linkpos=5&amp;log$=relatedreviews&amp;logdbfrom=pubmed"><span xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="invert">Review</span> Clinical pharmacology, therapeutic use and potential of COMT inhibitors in Parkinson's disease.</a><span class="source">[Drugs. 2000]</span><div class="brieflinkpop offscreen_noflow"><span xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="invert">Review</span> Clinical pharmacology, therapeutic use and potential of COMT inhibitors in Parkinson's disease.<div class="brieflinkpopdesc"><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="author">Kaakkola S. </em><em xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" class="cit">Drugs. 2000 Jun; 59(6):1233-50. </em></div></div></li></ul><a class="seemore" href="/sites/entrez?db=pubmed&amp;cmd=link&amp;linkname=pubmed_pubmed_reviews&amp;uid=31643888" ref="ordinalpos=1&amp;log$=relatedreviews_seeall&amp;logdbfrom=pubmed">See reviews...</a><a class="seemore" href="/sites/entrez?db=pubmed&amp;cmd=link&amp;linkname=pubmed_pubmed&amp;uid=31643888" ref="ordinalpos=1&amp;log$=relatedarticles_seeall&amp;logdbfrom=pubmed">See all...</a></div></div><div class="portlet"><div class="portlet_head"><div class="portlet_title"><h3><span>Recent Activity</span></h3></div><a name="Shutter" sid="1" href="#" class="portlet_shutter" title="Show/hide content" remembercollapsed="true" pgsec_name="recent_activity" id="Shutter"></a></div><div class="portlet_content"><div xmlns:np="http://ncbi.gov/portal/XSLT/namespace" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" id="HTDisplay" class=""><div class="action"><a href="javascript:historyDisplayState('ClearHT')">Clear</a><a href="javascript:historyDisplayState('HTOff')" class="HTOn">Turn Off</a><a href="javascript:historyDisplayState('HTOn')" class="HTOff">Turn On</a></div><ul id="activity"><li class="ra_rcd ralinkpopper two_line"><a class="htb ralinkpopperctrl" ref="log$=activity&amp;linkpos=1" href="/portal/utils/pageresolver.fcgi?recordid=67c8e20bf4a390645e38fe60">Tolcapone - LiverTox</a><div class="ralinkpop offscreen_noflow">Tolcapone - LiverTox<div class="brieflinkpopdesc"></div></div><div class="tertiary"></div></li><li class="ra_rcd ralinkpopper two_line"><a class="htb ralinkpopperctrl" ref="log$=activity&amp;linkpos=2" href="/portal/utils/pageresolver.fcgi?recordid=67c8e20ab15b832ebc16eb68">Tofacitinib - LiverTox</a><div class="ralinkpop offscreen_noflow">Tofacitinib - LiverTox<div class="brieflinkpopdesc"></div></div><div class="tertiary"></div></li><li class="ra_rcd ralinkpopper two_line"><a class="htb ralinkpopperctrl" ref="log$=activity&amp;linkpos=3" href="/portal/utils/pageresolver.fcgi?recordid=67c8e209f4a390645e38f670">Tocilizumab - LiverTox</a><div class="ralinkpop offscreen_noflow">Tocilizumab - LiverTox<div class="brieflinkpopdesc"></div></div><div class="tertiary"></div></li><li class="ra_rcd ralinkpopper two_line"><a class="htb ralinkpopperctrl" ref="log$=activity&amp;linkpos=4" href="/portal/utils/pageresolver.fcgi?recordid=67c8e208b15b832ebc16e324">Tobramycin - LiverTox</a><div class="ralinkpop offscreen_noflow">Tobramycin - LiverTox<div class="brieflinkpopdesc"></div></div><div class="tertiary"></div></li><li class="ra_rcd ralinkpopper two_line"><a class="htb ralinkpopperctrl" ref="log$=activity&amp;linkpos=5" href="/portal/utils/pageresolver.fcgi?recordid=67c8e206b15b832ebc16df0c">Tizanidine - LiverTox</a><div class="ralinkpop offscreen_noflow">Tizanidine - LiverTox<div class="brieflinkpopdesc"></div></div><div class="tertiary"></div></li></ul><p class="HTOn">Your browsing activity is empty.</p><p class="HTOff">Activity recording is turned off.</p><p id="turnOn" class="HTOff"><a href="javascript:historyDisplayState('HTOn')">Turn recording back on</a></p><a class="seemore" href="/sites/myncbi/recentactivity">See more...</a></div></div></div>
<!-- Custom content below discovery portlets -->
<div class="col7">
</div>
</div>
</div>
<!-- Custom content after all -->
<div class="col8">
</div>
<div class="col9">
</div>
<script type="text/javascript" src="/corehtml/pmc/js/jquery.scrollTo-1.4.2.js"></script>
<script type="text/javascript">
(function($){
$('.skiplink').each(function(i, item){
var href = $($(item).attr('href'));
href.attr('tabindex', '-1').addClass('skiptarget'); // ensure the target can receive focus
$(item).on('click', function(event){
event.preventDefault();
$.scrollTo(href, 0, {
onAfter: function(){
href.focus();
}
});
});
});
})(jQuery);
</script>
</div>
<div class="bottom">
<div id="NCBIFooter_dynamic">
<!--<component id="Breadcrumbs" label="breadcrumbs"/>
<component id="Breadcrumbs" label="helpdesk"/>-->
</div>
<div class="footer" id="footer">
<section class="icon-section">
<div id="icon-section-header" class="icon-section_header">Follow NCBI</div>
<div class="grid-container container">
<div class="icon-section_container">
<a class="footer-icon" id="footer_twitter" href="https://twitter.com/ncbi" aria-label="Twitter"><svg xmlns="http://www.w3.org/2000/svg" data-name="Layer 1" viewBox="0 0 300 300">
<defs>
<style>
.cls-11 {
fill: #737373;
}
</style>
</defs>
<title>Twitter</title>
<path class="cls-11" d="M250.11,105.48c-7,3.14-13,3.25-19.27.14,8.12-4.86,8.49-8.27,11.43-17.46a78.8,78.8,0,0,1-25,9.55,39.35,39.35,0,0,0-67,35.85,111.6,111.6,0,0,1-81-41.08A39.37,39.37,0,0,0,81.47,145a39.08,39.08,0,0,1-17.8-4.92c0,.17,0,.33,0,.5a39.32,39.32,0,0,0,31.53,38.54,39.26,39.26,0,0,1-17.75.68,39.37,39.37,0,0,0,36.72,27.3A79.07,79.07,0,0,1,56,223.34,111.31,111.31,0,0,0,116.22,241c72.3,0,111.83-59.9,111.83-111.84,0-1.71,0-3.4-.1-5.09C235.62,118.54,244.84,113.37,250.11,105.48Z">
</path>
</svg></a>
<a class="footer-icon" id="footer_facebook" href="https://www.facebook.com/ncbi.nlm" aria-label="Facebook"><svg xmlns="http://www.w3.org/2000/svg" data-name="Layer 1" viewBox="0 0 300 300">
<title>Facebook</title>
<path class="cls-11" d="M210.5,115.12H171.74V97.82c0-8.14,5.39-10,9.19-10h27.14V52l-39.32-.12c-35.66,0-42.42,26.68-42.42,43.77v19.48H99.09v36.32h27.24v109h45.41v-109h35Z">
</path>
</svg></a>
<a class="footer-icon" id="footer_linkedin" href="https://www.linkedin.com/company/ncbinlm" aria-label="LinkedIn"><svg xmlns="http://www.w3.org/2000/svg" data-name="Layer 1" viewBox="0 0 300 300">
<title>LinkedIn</title>
<path class="cls-11" d="M101.64,243.37H57.79v-114h43.85Zm-22-131.54h-.26c-13.25,0-21.82-10.36-21.82-21.76,0-11.65,8.84-21.15,22.33-21.15S101.7,78.72,102,90.38C102,101.77,93.4,111.83,79.63,111.83Zm100.93,52.61A17.54,17.54,0,0,0,163,182v61.39H119.18s.51-105.23,0-114H163v13a54.33,54.33,0,0,1,34.54-12.66c26,0,44.39,18.8,44.39,55.29v58.35H198.1V182A17.54,17.54,0,0,0,180.56,164.44Z">
</path>
</svg></a>
<a class="footer-icon" id="footer_github" href="https://github.com/ncbi" aria-label="GitHub"><svg xmlns="http://www.w3.org/2000/svg" data-name="Layer 1" viewBox="0 0 300 300">
<defs>
<style>
.cls-11,
.cls-12 {
fill: #737373;
}
.cls-11 {
fill-rule: evenodd;
}
</style>
</defs>
<title>GitHub</title>
<path class="cls-11" d="M151.36,47.28a105.76,105.76,0,0,0-33.43,206.1c5.28,1,7.22-2.3,7.22-5.09,0-2.52-.09-10.85-.14-19.69-29.42,6.4-35.63-12.48-35.63-12.48-4.81-12.22-11.74-15.47-11.74-15.47-9.59-6.56.73-6.43.73-6.43,10.61.75,16.21,10.9,16.21,10.9,9.43,16.17,24.73,11.49,30.77,8.79,1-6.83,3.69-11.5,6.71-14.14C108.57,197.1,83.88,188,83.88,147.51a40.92,40.92,0,0,1,10.9-28.39c-1.1-2.66-4.72-13.42,1-28,0,0,8.88-2.84,29.09,10.84a100.26,100.26,0,0,1,53,0C198,88.3,206.9,91.14,206.9,91.14c5.76,14.56,2.14,25.32,1,28a40.87,40.87,0,0,1,10.89,28.39c0,40.62-24.74,49.56-48.29,52.18,3.79,3.28,7.17,9.71,7.17,19.58,0,14.15-.12,25.54-.12,29,0,2.82,1.9,6.11,7.26,5.07A105.76,105.76,0,0,0,151.36,47.28Z">
</path>
<path class="cls-12" d="M85.66,199.12c-.23.52-1.06.68-1.81.32s-1.2-1.06-.95-1.59,1.06-.69,1.82-.33,1.21,1.07.94,1.6Zm-1.3-1">
</path>
<path class="cls-12" d="M90,203.89c-.51.47-1.49.25-2.16-.49a1.61,1.61,0,0,1-.31-2.19c.52-.47,1.47-.25,2.17.49s.82,1.72.3,2.19Zm-1-1.08">
</path>
<path class="cls-12" d="M94.12,210c-.65.46-1.71,0-2.37-.91s-.64-2.07,0-2.52,1.7,0,2.36.89.65,2.08,0,2.54Zm0,0"></path>
<path class="cls-12" d="M99.83,215.87c-.58.64-1.82.47-2.72-.41s-1.18-2.06-.6-2.7,1.83-.46,2.74.41,1.2,2.07.58,2.7Zm0,0">
</path>
<path class="cls-12" d="M107.71,219.29c-.26.82-1.45,1.2-2.64.85s-2-1.34-1.74-2.17,1.44-1.23,2.65-.85,2,1.32,1.73,2.17Zm0,0">
</path>
<path class="cls-12" d="M116.36,219.92c0,.87-1,1.59-2.24,1.61s-2.29-.68-2.3-1.54,1-1.59,2.26-1.61,2.28.67,2.28,1.54Zm0,0">
</path>
<path class="cls-12" d="M124.42,218.55c.15.85-.73,1.72-2,1.95s-2.37-.3-2.52-1.14.73-1.75,2-2,2.37.29,2.53,1.16Zm0,0"></path>
</svg></a>
<a class="footer-icon" id="footer_blog" href="https://ncbiinsights.ncbi.nlm.nih.gov/" aria-label="Blog">
<svg xmlns="http://www.w3.org/2000/svg" id="Layer_1" data-name="Layer 1" viewBox="0 0 40 40">
<defs><style>.cls-1{fill:#737373;}</style></defs>
<title>NCBI Insights Blog</title>
<path class="cls-1" d="M14,30a4,4,0,1,1-4-4,4,4,0,0,1,4,4Zm11,3A19,19,0,0,0,7.05,15a1,1,0,0,0-1,1v3a1,1,0,0,0,.93,1A14,14,0,0,1,20,33.07,1,1,0,0,0,21,34h3a1,1,0,0,0,1-1Zm9,0A28,28,0,0,0,7,6,1,1,0,0,0,6,7v3a1,1,0,0,0,1,1A23,23,0,0,1,29,33a1,1,0,0,0,1,1h3A1,1,0,0,0,34,33Z"></path>
</svg>
</a>
</div>
</div>
</section>
<section class="container-fluid bg-primary">
<div class="container pt-5">
<div class="row mt-3">
<div class="col-lg-3 col-12">
<p><a class="text-white" href="https://www.nlm.nih.gov/socialmedia/index.html">Connect with NLM</a></p>
<ul class="list-inline social_media">
<li class="list-inline-item"><a href="https://twitter.com/NLM_NIH" aria-label="Twitter" target="_blank" rel="noopener noreferrer"><svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" x="0px" y="0px" viewBox="0 0 249 249" style="enable-background:new 0 0 249 249;" xml:space="preserve">
<style type="text/css">
.st20 {
fill: #FFFFFF;
}
.st30 {
fill: none;
stroke: #FFFFFF;
stroke-width: 8;
stroke-miterlimit: 10;
}
</style>
<title>Twitter</title>
<g>
<g>
<g>
<path class="st20" d="M192.9,88.1c-5,2.2-9.2,2.3-13.6,0.1c5.7-3.4,6-5.8,8.1-12.3c-5.4,3.2-11.4,5.5-17.6,6.7 c-10.5-11.2-28.1-11.7-39.2-1.2c-7.2,6.8-10.2,16.9-8,26.5c-22.3-1.1-43.1-11.7-57.2-29C58,91.6,61.8,107.9,74,116 c-4.4-0.1-8.7-1.3-12.6-3.4c0,0.1,0,0.2,0,0.4c0,13.2,9.3,24.6,22.3,27.2c-4.1,1.1-8.4,1.3-12.5,0.5c3.6,11.3,14,19,25.9,19.3 c-11.6,9.1-26.4,13.2-41.1,11.5c12.7,8.1,27.4,12.5,42.5,12.5c51,0,78.9-42.2,78.9-78.9c0-1.2,0-2.4-0.1-3.6 C182.7,97.4,189.2,93.7,192.9,88.1z"></path>
</g>
</g>
<circle class="st30" cx="124.4" cy="128.8" r="108.2"></circle>
</g>
</svg></a></li>
<li class="list-inline-item"><a href="https://www.facebook.com/nationallibraryofmedicine" aria-label="Facebook" rel="noopener noreferrer" target="_blank">
<svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" x="0px" y="0px" viewBox="0 0 249 249" style="enable-background:new 0 0 249 249;" xml:space="preserve">
<style type="text/css">
.st10 {
fill: #FFFFFF;
}
.st110 {
fill: none;
stroke: #FFFFFF;
stroke-width: 8;
stroke-miterlimit: 10;
}
</style>
<title>Facebook</title>
<g>
<g>
<path class="st10" d="M159,99.1h-24V88.4c0-5,3.3-6.2,5.7-6.2h16.8V60l-24.4-0.1c-22.1,0-26.2,16.5-26.2,27.1v12.1H90v22.5h16.9 v67.5H135v-67.5h21.7L159,99.1z"></path>
</g>
</g>
<circle class="st110" cx="123.6" cy="123.2" r="108.2"></circle>
</svg>
</a></li>
<li class="list-inline-item"><a href="https://www.youtube.com/user/NLMNIH" aria-label="Youtube" target="_blank" rel="noopener noreferrer"><svg xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink" version="1.1" x="0px" y="0px" viewBox="0 0 249 249" style="enable-background:new 0 0 249 249;" xml:space="preserve">
<title>Youtube</title>
<style type="text/css">
.st4 {
fill: none;
stroke: #FFFFFF;
stroke-width: 8;
stroke-miterlimit: 10;
}
.st5 {
fill: #FFFFFF;
}
</style>
<circle class="st4" cx="124.2" cy="123.4" r="108.2"></circle>
<g transform="translate(0,-952.36218)">
<path class="st5" d="M88.4,1037.4c-10.4,0-18.7,8.3-18.7,18.7v40.1c0,10.4,8.3,18.7,18.7,18.7h72.1c10.4,0,18.7-8.3,18.7-18.7 v-40.1c0-10.4-8.3-18.7-18.7-18.7H88.4z M115.2,1058.8l29.4,17.4l-29.4,17.4V1058.8z"></path>
</g>
</svg></a></li>
</ul>
</div>
<div class="col-lg-3 col-12">
<p class="address_footer text-white">National Library of Medicine<br />
<a href="https://www.google.com/maps/place/8600+Rockville+Pike,+Bethesda,+MD+20894/@38.9959508,-77.101021,17z/data=!3m1!4b1!4m5!3m4!1s0x89b7c95e25765ddb:0x19156f88b27635b8!8m2!3d38.9959508!4d-77.0988323" class="text-white" target="_blank" rel="noopener noreferrer">8600 Rockville Pike<br />
Bethesda, MD 20894</a></p>
</div>
<div class="col-lg-3 col-12 centered-lg">
<p><a href="https://www.nlm.nih.gov/web_policies.html" class="text-white">Web Policies</a><br />
<a href="https://www.nih.gov/institutes-nih/nih-office-director/office-communications-public-liaison/freedom-information-act-office" class="text-white">FOIA</a><br />
<a href="https://www.hhs.gov/vulnerability-disclosure-policy/index.html" class="text-white" id="vdp">HHS Vulnerability Disclosure</a></p>
</div>
<div class="col-lg-3 col-12 centered-lg">
<p><a class="supportLink text-white" href="https://support.nlm.nih.gov/">Help</a><br />
<a href="https://www.nlm.nih.gov/accessibility.html" class="text-white">Accessibility</a><br />
<a href="https://www.nlm.nih.gov/careers/careers.html" class="text-white">Careers</a></p>
</div>
</div>
<div class="row">
<div class="col-lg-12 centered-lg">
<nav class="bottom-links">
<ul class="mt-3">
<li>
<a class="text-white" href="//www.nlm.nih.gov/">NLM</a>
</li>
<li>
<a class="text-white" href="https://www.nih.gov/">NIH</a>
</li>
<li>
<a class="text-white" href="https://www.hhs.gov/">HHS</a>
</li>
<li>
<a class="text-white" href="https://www.usa.gov/">USA.gov</a>
</li>
</ul>
</nav>
</div>
</div>
</div>
</section>
<script type="text/javascript" src="/portal/portal3rc.fcgi/rlib/js/InstrumentOmnitureBaseJS/InstrumentNCBIConfigJS/InstrumentNCBIBaseJS/InstrumentPageStarterJS.js?v=1"> </script>
<script type="text/javascript" src="/portal/portal3rc.fcgi/static/js/hfjs2.js"> </script>
</div>
</div>
</div>
<!--/.page-->
</div>
<!--/.wrap-->
</div><!-- /.twelve_col -->
</div>
<!-- /.grid -->
<span class="PAFAppResources"></span>
<!-- BESelector tab -->
<noscript><img alt="statistics" src="/stat?jsdisabled=true&amp;ncbi_db=books&amp;ncbi_pdid=book-part&amp;ncbi_acc=NBK548573&amp;ncbi_domain=livertox&amp;ncbi_report=record&amp;ncbi_type=fulltext&amp;ncbi_objectid=&amp;ncbi_pcid=/NBK548573/&amp;ncbi_pagename=Tolcapone - LiverTox - NCBI Bookshelf&amp;ncbi_bookparttype=chapter&amp;ncbi_app=bookshelf" /></noscript>
<!-- usually for JS scripts at page bottom -->
<!--<component id="PageFixtures" label="styles"></component>-->
<!-- CE8B5AF87C7FFCB1_0191SID /projects/books/PBooks@9.11 portal107 v4.1.r689238 Tue, Oct 22 2024 16:10:51 -->
<span id="portal-csrf-token" style="display:none" data-token="CE8B5AF87C7FFCB1_0191SID"></span>
<script type="text/javascript" src="//static.pubmed.gov/portal/portal3rc.fcgi/4216699/js/3879255/4121861/3501987/4008961/3893018/3821238/4062932/4209313/4212053/4076480/3921943/3400083/3426610.js" snapshot="books"></script></body>
</html>