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A change in the formulation of tenofovir gel, an anti-HIV geldeveloped for vaginal use, may make it safer to use in the rectum,suggests a study published online this week in the Journal of Antimicrobial Chemotherapy. In laboratory tests of rectal tissue, researchers from theMicrobicide Trials Network (MTN) found that the reformulated gelwas less harmful to the lining of the rectum than the originalvaginal formulation, and just as effective in protecting cellsagainst HIV . "The lining of the rectum is much more fragile than the vaginalepithelium, so we can't be certain a product like tenofovir gelthat is safe for vaginal use will be completely safe to use in therectum," said lead study author Charlene Dezzutti, Ph.D., associateprofessor of obstetrics, gynecology and reproductive sciences atthe University of Pittsburgh School of Medicine and principalinvestigator of the MTN Network Laboratory. "We are very encouragedby our laboratory data that suggest the reformulated gel could besafer for rectal use, and serve as a dual compartment gel for usein both the vagina and rectum." Tenofovir gel has shown some promise in reducing HIV risk in womenthrough vaginal sex. But because the rectal epithelium - the liningof the rectum that serves as the first line of defense against HIV- is much thinner than the vaginal lining, the gel may not be safeor effective to use rectally. Indeed, unprotected anal sex is 10 to20 times more likely to result in HIV infection than unprotectedvaginal intercourse. By its nature, tenofovir gel is hyperosmolar -contains a higher concentration of sugars and salts relative tocells. This quality could have a harmful effect on the rectallining by causing epithelial cells to shrink as they purge water toachieve balance. Weakened in this manner, the rectal epithelium maybe less able to protect against HIV. To make tenofovir gel safe and more amenable to rectal use,researchers from CONRAD, a research organization which holds therights to develop the gel, reformulated it with a reduced amount ofglycerin, a common additive found in many gel-like products. Inlaboratory tests conducted by MTN researchers, the reformulated gelwas three times less likely to cause cells in rectal tissue torelease water, and equally effective against HIV as the vaginalformulation. Data from an early phase clinical trial of the reduced glycerin gelpresented in March 2012 at the 19th Conference on Retroviruses andOpportunistic Infections (CROI), suggested it was safe andacceptable in 65 HIV-negative men and women who used it rectallyonce a day for one week. Results from this study, called MTN-007,and future studies will have important implications for thedevelopment of a rectal microbicide that could help protect againstHIV or other sexually transmitted infections during anal sex. As follow-up to MTN-007, researchers are now planning a Phase II,multi-site trial called MTN-017 that will involve 186 men who havesex with men, and transgender women at clinical sites in Peru,South Africa, Thailand, and the U.S. Participants will cyclethrough three study regimens: reduced glycerin tenofovir gel useddaily, reduced glycerin tenofovir gel used before and after analsex, and daily use of the antiretroviral tablet Truvada®.MTN-017 will allow researchers to collect additional information Tenofovir gel contains the antiretroviral tenofovir, which iscommonly used in the treatment of HIV. The vaginal formulation oftenofovir gel was found safe and effective in reducing the risk ofHIV in women who used it before and after vaginal sex in a studycalled CAPRISA 004. More recently, however, MTN researchersconducting the VOICE Study closed the tenofovir gel arm of thetrial after a routine review of study data determined that the gel,while safe, was not effective in preventing HIV among the women inthat study group, who were asked to apply it vaginally every day.In the meantime, a Phase III trial called FACTS 001 is currentlyevaluating the vaginal formulation of tenofovir gel using the sameregimen as CAPRISA 004, with results expected in 2014. Additional References Citations. The e-commerce company in China offers quality products such as Hiking Altimeter , Outdoor Altimeter Manufacturer, and more. For more , please visit Digital Altimeter Compass today!
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