Purpose of review: This review will summarize the rationale for developing rectal microbicides and discuss recent developments in the preclinical and clinical evaluation of these products.
Recent findings: It is clear that heterosexual women often engage in anal intercourse and that men who have sex with men can be found in both the developed and developing world. These observations have catalyzed the need to assess rectal safety of vaginal products and develop rectal specific microbicides. New approaches to the preclinical evaluation of rectal microbicides include the use of transgenic mice, nonhuman primate studies, and human colorectal explant systems. The design of phase I rectal safety studies is becoming increasingly sophisticated, including safety biomarkers to evaluate microbicide-induced immunotoxicity.
Summary: There is growing acceptance that all vaginal microbicide candidates moving towards effectiveness studies should be evaluated for rectal safety. In addition, there is increasing awareness of the need to develop rectal specific microbicide formulations.