Safety and Acceptability Study of the UC-781 Microbicide Gel Applied Rectally

The purpose of this study is to obtain preliminary data on the safety and acceptability of UC-781 vaginal microbicide gel (0.1% and 0.25%) versus placebo when rectally administered in HIV-1 seronegative adults. Participants will enter a screening period, which includes Visit 1 and if necessary a medication washout period. Subjects who are deemed eligible after this screening period will return for a baseline evaluation (Visit 2), including clinical evaluation and mucosal specimen collection, as well as the Baseline Behavioral Questionnaire (BBQ). The BBQ will be administered by Computer Assisted Self-Interview (CASI). Subjects may complete the web-based CASI in the privacy of their own home. If a subject does not have access to the Internet, prefers to complete the BBQ at the study site, or requires assistance in using the CASI, he or she will be accommodated at the study site. After completing Visits 1 and 2, eligible subjects will be randomized to one of three groups: 0.1% UC-781 gel, 0.25% UC-781 gel, or a placebo gel (12 per group). A subset of 9 subjects (3 from each group) will also participate in a pK sub-study, which will include 6 timepoints (Visit 3- pre, 0.25 hr, 2 hr, 4 hr, Visit 3A- 24 hr, and Visit 5- 1 day post-QD dose). During randomization, study staff will be notified if the participant is randomized to the pK substudy. This study will involve 2 stages of treatment. Each treatment stage is independent of the other. This study aims to examine the effects of 2 different dosing regimens, NOT cumulative safety over the both stages. Once randomized, subjects will return to the clinic (Visit 3), where a single dose of the study gel (Treatment Stage 1) will be administered followed by clinical evaluation, including flexible sigmoidoscopy, and sample collection. Subjects will return to the clinic for Treatment Stage 2 Clearance (Visit 4), in the week prior to beginning Treatment Stage 2. If given clearance, the subject may begin Treatment Stage 2. In Treatment Stage 2, subjects will begin to self-administer once daily outpatient doses of the study gel for 7 days. After completion of Stage 2 the subject will complete a Product Acceptability Questionnaire (PAQ) by CASI and return to clinic for evaluation and specimen collection (Visit 5). After completion of Visit 5, subjects will be contacted by an interviewer to complete an in-depth phone interview regarding product acceptability.