‘Rectal-Friendly’ Version Of Tenofovir Gel
A new clinical trial conducted by the U.S. National Institutes of Health categorizes tenofovir (marketed in the United States under the name of Viread) as acceptable and safe to prescribe. Tenofovir is an antiretroviral drug prescribed, based on previous studies, to reduce the number of HIV infections. The study was funded by the Microbicide Trials Network and was presented on the 6th of March at the 19th Conference on Retroviruses and Opportunistic Infections, held in Seattle. Scientists suggest that the new results will be an important step towards developing new rectal microbicide drugs that could prevent HIV infections transmitted through anal sex.
Microbicide drugs are chemical substances that have the ability to destroy specific microorganisms. Microbicides can be found as gels, creams, tables or even films. Most of them are gels and creams and are applied on the inside of either the rectum or the vagina. Until now, the use of microbicides was to prevent the infection with HIV through unprotected vaginal sex but future studies will focus on developing new products that would prevent HIV infections caused by unprotected anal sex, as studies show that unprotected anal sex is 20 times riskier than unprotected vaginal sex.
The current study was based on tests conducted on 65 men and women from three different locations. These locations were the University of Pittsburgh, the University of Alabama and Fenway Health in Boston. This study represents a follow-up trial which assessed the impact of rectally using a vaginal formulation of tenofovir. Results showed a present antiviral effect but arguable side effects.
Scientists randomly separated the patients into four study groups. Patients in the first group received a new rectal formulation of tenofovir gel. The patients in the second group received a gel containing spermicide. The patients in the third group were given a placebo gel. Patients in the last group did not receive any gel but participated in all of the procedures and tests that were conducted on the other patients.
The evaluation of the results of the study shows that there are no important differences between the side effects of the three types of gel. Insignificant side effects were reported by almost 80 percent of the participants whilst bearable side effects were reported by 18 percent of the participants. More than 90 percent of tested patients used the products accordingly, following the instruction given prior to the start of the trial. Almost 90 percent of the test subjects who were asked whether or not they would use the tenofovir gel in the future responded affirmative. In comparison, 93 percent of patients using the placebo gel responded affirmative to the same question while only 63 percent of the patients using the spermicide had the same answer.
Besides safety and tolerability of the new rectal formulation of the tenofovir gel, scientists also conducted gene expression tests, whilst noting down every change that appeared and was believed to be an effect of the drug.
“These findings tell us that the ‘rectal-friendly’ version of tenofovir gel was much better tolerated than the vaginal formulation of the gel when used in the rectum,” said professor Ian McGowan, M.D., Ph.D., while also adding that “We are very encouraged that the rectal gel was quite safe, and that most people who used it said they would be willing to use it in the future”.
A future follow-up for the current study is already being planned. The follow-up study will be a trial on 186 patients from countries such as South Africa, Thailand, the United States and even Peru. This new study will have patients divided into two groups that will analyze the effects and side effects of the tenofovir rectal gel applied daily, before and after anal sex and a third group of patients that will receive an antiretroviral tablet called Truvada.