• The safety and toxicity of 0.1% and 0.25% UC-781 carbomer gel compared to placebo gel in HIV uninfected, sexually active women and men
  

• Effects on vaginal microflora
  
• Systemic absorption
  
• Use acceptability in trial populations
  

45 women and 45 men, all healthy and sexually active, 21-45 years old, without HIV infection, will be enrolled in Francistown and Gaborone, Botswana. Volunteers will be randomized to receive either 0.1% or 0.25% UC-781 carbomer gel or placebo gel (3 arms. Women will be instructed to apply gel intravaginally, morning and evening, and prior to sex (always with male condom use) for 14 consecutive days. Men will be instructed to apply gel topically for 14 consecutive nights, before bed, allow to dry overnight, and wash it off in the morning. Additionally instructed never to use gel during sex but always to use condoms. Volunteers will be seen weekly for evaluation of symptoms, laboratory toxicities, genital exam findings (with colposcopy for women, and plasma drug levels. Acceptability will be assessed in focus groups in the month after completing gel use.

Inclusion Criteria:

• 21-45 years old
• citizen of Botswana
• willing to use condoms for 14 days
• PAP smear (normal, inflammation, ASCUS)
• regular menses or amenorrhea
• lives within 1 hour of a study clinic
• pass comprehension test
• provide written informed consent

Exclusion Criteria:

• genital mucosal disruption at screening
• genital surgery within past 8 weeks
• pregnant within past 8 weeks
• currently breastfeeding
• prior hysterectomy
• plans to move within 2 months
• ALT, AST, total bilirubin, or creatinine Grade 2 or above
• Prothrombin or partial thromboplastin time Grade 2 or above
• In other drug/vaccine safety trial
• Has more than one sexual partner in past month
• Unwilling/unsure they can have sex at least twice weekly for 2 weeks
• Any other condition that investigator believes will interfere with the evaluation of study objectives