Objective: The aim of this study was to investigate the safety and effectiveness of orally administered SP-303 in patients with AIDS and diarrhea.

Methods: This is a multicenter, phase II, randomized, double blind, placebo-controlled study. HIV-positive subjects with a history of a CD4 count <200 or an AIDS-defining illness were admitted to an inpatient study unit and screened for diarrhea defined as at least three abnormal (i.e., soft or watery) stools and >200 g of abnormal stool weight over a 24-h period. Subjects discontinued all antidiarrheal agents >24 h before enrollment. Stool samples were studied for routine pathogens. Subjects received 500 mg p.o. of SP-303 or placebo every 6 h for 96 h (4 days). Stool frequency and weights were recorded. Subjects were monitored for symptoms and side effects and were seen 1 wk later in follow-up.

Results: A total of 26 subjects received SP-303, and 25 received placebo. There were no significant demographic differences between treatment arms. A total of 41 subjects (80%) were receiving antiretroviral therapy and 39 subjects (77%) were receiving at least one protease inhibitor. Stool studies revealed no pathogens in 48 of 51 patients (94%). There were no serious adverse events or laboratory abnormalities. The SP-303 treatment group demonstrated a mean reduction from baseline stool weight of 451 g/24 h versus 150 g/24 h with placebo on day 4 of treatment (p = 0.14), and a mean reduction in abnormal stool frequency of three abnormal stools in 24 h versus two in 24 h in the placebo group (p = 0.30). Daily measures analysis over 4 days of treatment demonstrated that SP-303 subjects had a significant reduction in stool weight (p = 0.008) and abnormal stool frequency (p = 0.04) when compared to placebo-treated subjects.

Conclusions: SP-303 is safe and well tolerated. These results suggest that SP-303 may be effective in reducing stool weight and frequency in patients with AIDS and diarrhea.