Novel product aimed at HIV prevention

By CHARALAMPOS VALMAS, Ph.D, GlobalData

LONDON – Last week at the American Association of Pharmaceutical Scientists Annual Meeting and Exposition in Chicago, researchers presented their results on a novel product aimed at the prevention of HIV transmission through sexual intercourse. The new prophylactic is an intravaginal ring made of plastic tubing filled with a paste of tenofovir (an antiretroviral that inhibits the reverse transcription of HIV), and absorbs water when inserted high into the vagina, thereby releasing the drug. The ring is simple to make and hundreds can be produced a day, although no estimate for the cost of the process was given.

The presentation was made by scientiests from the University of Utah and CONRAD, a division of the Department of Obstetrics and Gynecology at Eastern Virginia Medical School that focuses on reproductive health research and contraceptive development.

The efficacy of topically applied 1% tenofovir gel was previously evaluated in the CAPRISA 004 trial, published in Science in 2010, showing a reduction in HIV incidence ranging from 28% to 54%. Such a discrepancy was attributed to varying levels of adherence, as the recommended application was before and after intercourse. The intravaginal ring should have increased compliance due to its ease of use, and it can deliver up to 10mg/day for a period exceeding 90 days, thereby conferring long-term protection with a single application. The levels of tenofovir in plasma, vaginal tissue and fluid were near or exceeded peak concentration observed in the gel-treated arm of the trial. By comparison, previous vaginal rings could only release micrograms per day; advances in materials science have led to the development of specific hydrophilic polymers with high permeability.

Prophylactics with approved anti-retrovirals

With an effective vaccine against HIV still years away, the current trend is to try and decrease HIV transmission with prophylactics that utilize approved anti-retrovirals. In July 2012, the FDA approved Gilead’s Truvada (emtricitabine/tenofovir disoproxil fumarate), a drug routinely used for the treatment of HIV, for Pre-Exposure Prophylaxis (PrEP). PrEP is indicated for uninfected individuals who are at high risk of HIV exposure (e.g., men who have sex with men and people with HIV-infected partners). Truvada, taken daily, reduced the likelihood of HIV infection by 75% in heterosexual couples and 42% in same-sex couples. However, concerns of long-term renal and bone toxicity, and the potential emergence and spread of drug-resistant virus through the inadvertent use of PrEP in people who are already infected or become infected while on the drug, is a potential major barrier for the widespread use of Truvada as a prophylactic. Also, its use might be limited by the cost and policies adHighsnobiety Sneakers