Topical microbicides are products designed to prevent the sexual transmission of HIV and other disease pathogens. Studies have shown that nonoxynol-9, a detergent microbicide, can cause mucosal erosion and ulceration and increased risk of HIV infection. Attention has been given to developing non-detergent topical microbicides, such as BufferGel and PRO 2000/5 Gel. Studies have shown these products to be safe and acceptable for vaginal use [AS PER AMENDMENT 08/20/01: "however, none of the clinical studies to date have investigated the effects on the penile epithelium and urethral mucosa" has been replaced with: Phase I trials also have been conducted to assess the safety of BufferGel and PRO 2000/5 Gel (P) on the penile epithelium and urethral mucosa. In 1 trial, HIV-uninfected men applied either PRO 2000/5 or a gel containing the inactive ingredients of PRO 2000/5 for 7 days. A few patients reported mild symptoms of genital itching, tingling, irritation, dryness, discoloration, or flaking of the dried gel. In a similar trial comparing BufferGel and K-Y Jelly, a few patients reported similar symptoms.] It is important to determine whether the frequency and severity of adverse events experienced by men is comparable to that observed among women. It is also important to determine whether these adverse events are similar between circumcised and uncircumcised men.

Patients are assigned randomly to 1 of 6 possible sequences of product use. Patients complete 3 weeks of nightly product application (7 consecutive nights each of BufferGel, PRO 2000/5 Gel, and placebo gel) separated by a one-week washout between product-use periods. Patients apply the gel to the shaft and glans of the penis at bedtime, leave on for a minimum of 6 hours, and wash off the next morning. Patients maintain a diary of product application and removal, side effects, and use of other medications. Follow-up evaluations, including a genital exam and urine testing, are performed after each product-use and washout period. [AS PER AMENDMENT 08/20/01: Digital photographs will be taken of any observed abnormality or normal area that is needed for clinical decision making and/or documentation purposes.] In addition, adherence is assessed, the patient diary is reviewed, and product acceptability questionnaires are administered after each product-use period. Patients receive monetary compensation for participation.