title: Rectal microbicide development.
abstract: OBJECTIVE
  Individuals practicing unprotected receptive anal intercourse are at particularly high risk of HIV infection. Men who have sex with men (MSM) in the developed and developing world continue to have disproportionate and increasing levels of HIV infection. The past few years have seen important progress in demonstrating the efficacy of oral pre-exposure prophylaxis (PrEP), vaginal microbicides, and treatment as prevention, but there has also been significant progress in the development of rectal microbicides. The purpose of this review is to summarize the status of rectal microbicide research and to identify opportunities, challenges, and future directions in this important field of HIV prevention.
  
  
  RESULTS
  Recent phase 1 rectal microbicide studies have characterized the safety, acceptability, compartmental pharmacokinetics, and pharmacodynamics of both UC781 and tenofovir gels. The tenofovir gel formulation used in vaginal studies was not well tolerated in the rectum and newer rectal-specific formulations have been developed and evaluated in phase 1 studies.
  
  
  CONCLUSIONS
  Complex phase 1 studies have provided important data on candidate rectal microbicides. Tenofovir gel is poised to move into phase 2 evaluation and it is possible that a phase 2B/3 effectiveness study could be initiated in the next 2-3 years.
authors.affiliation: University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, USA. imcgowan@pitt.edu
authors.forename: Ian
authors.initials: I
authors.lastname: McGowan
mesh_terms: D000225:Adenine / Q000008:administration & dosage / Q000009:adverse effects / Q000031:analogs & derivatives; D000285:Administration, Rectal; D000287:Administration, Topical; D000813:Anilides / Q000008:administration & dosage / Q000009:adverse effects; D019380:Anti-HIV Agents / Q000008:administration & dosage* / Q000009:adverse effects; D018890:Chemoprevention / Q000379:methods*; D017321:Clinical Trials, Phase I as Topic; D064420:Drug-Related Side Effects and Adverse Reactions / Q000453:epidemiology; D005663:Furans / Q000008:administration & dosage / Q000009:adverse effects; D015658:HIV Infections / Q000517:prevention & control*; D018451:Homosexuality, Male; D006801:Humans; D008297:Male; D063065:Organophosphonates / Q000008:administration & dosage / Q000009:adverse effects; D000068698:Tenofovir; D013854:Thioamides
chemical_list: D000813:Anilides; D019380:Anti-HIV Agents; D005663:Furans; D063065:Organophosphonates; D013854:Thioamides; D000068698:Tenofovir; D000225:Adenine; C100668:UC-781