First Test of Rectal Microbicide

The UCLA AIDS Institute has completed a study of a rectal microbicide that may prevent transmission of HIV during receptive anal sex. The study used HIV prevention drug UC781 which is a non-nucleoside reverse transcriptase inhibitor. It has recently passed Stage I clinical trials for preventing transmission of HIV through vaginal intercourse. The UCLA study was designed to test whether or not the drug was safe for rectal use.

by Till Krech used under CC 2.0

Normally stage I clinical trials are not testing for the effectiveness of a drug, they are testing whether of not the drug is safe enough to bother testing for effectiveness. In this case, in addition to determining that UC781 is safe for rectal use, results indicated that it does reduce infection of rectal tissue that is exposed to HIV in the laboratory.

Receptive anal sex is the most common form of HIV transmission among men who have sex with men. It also causes HIV transmission among women who have sex with men. This was the first clinical trial of a microbicide for preventing transmission of HIV from receptive anal sex, and an important first step in protecting against HIV transmission from anal sex.

As a stage I clinical trial, there are years of testing that still need to be done before researchers can be certain that UC781 is effective and safe for most people to use. This study used a gel formula that was designed for vaginal use, so the next step for researchers at UCLA is to repeat the trial with a gel designed for anal use.

2 Comments to “First Test of Rectal Microbicide”

  1. shawn says:

    how would one sign up to be a participant in this testing?

    • Jessica says:

      The best way to get involved with a clinical trial is to talk with your doctor. He or she should be able to find out what clinical trials are running in your area and whether or not you would be eligible for them. You can sometimes find clinical trials at or, however their listings are not always updated with current information.

      As far as we can tell, there aren’t any rectal microbicide tests enrolling participants at this time.

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