A flexible ring containing two anti-HIV drugs showed in laboratory tests that it can deliver therapeutic levels of both drugs for up to 30 days, researchers reported today at the International Microbicides Conference (M2010) in Pittsburgh, adding that they consider the ring near ready for testing of its safety in women. Vaginal rings have been used to deliver contraceptives and now this strategy is being applied for delivering formulations of microbicides to protect against HIV. Unlike gels that must be used every day or at the time of sex, rings can be inserted into the vagina and stay in for a month or longer. And, for certain drugs or drug combinations, these formulations may be the more optimal vehicles for delivery.
Another option to deliver drugs with less fuss or muss, are quick-dissolve films. In one study presented today, researchers described their progress in developing a vaginal film – smaller than a stick of gum and as thin as a sheet of paper – that after insertion into the vagina would melt away and disperse drug to cells to protect against HIV. Laboratory tests of a similar approach – an almond-shaped vaginal tablet – found the tablets dissolved quickly yet still delivered sustained levels of anti-HIV drugs over several hours.
M2010 is taking place May 22-25 at Pittsburgh's David L. Lawrence Convention Center. Nearly 1,000 participants from 47 different countries are attending the meeting to hear about the latest developments in HIV prevention research. Summaries of some of the studies looking at new microbicide formulations are provided below.
Vaginal ring with two anti-HIV drugs nears benchmark for clinical testing of its safety in women
An intravaginal ring formulated with two anti-HIV drugs – dapivirine and maraviroc – can deliver therapeutic levels of both drugs for as long as a month, according to laboratory studies. Based on these and other findings, the ring is a good candidate for testing in clinical safety trials, reported Andrew Loxley, Ph.D., from Particle Sciences, Inc., of Bethlehem, Pa. Vaginal rings are small, flexible devices designed to allow for the slow delivery of a drug or multiple drugs over time. As a potential method for preventing sexual transmission of HIV, rings are seen as an alternative to microbicide gels that must be used every day or at the time of sex. Dapivirine, also known as TMC-120, belongs to a class of anti-HIV drugs called non-nucleoside reverse transcriptase inhibitors that bind to and disable HIV's reverse transcriptase enzyme, a protein that HIV needs to make more copies of itself. Maraviroc is a type of drug called an entry inhibitor that prevents HIV from entering a healthy cell. The current study indicates that inside the vaginal ring, the two drugs work well side-by-side with the activity and structure of each drug not being affected by the presence of the other. High amounts of each drug were still being released from the ring at 15 days and continued to be delivered for up to 30 days. Even after being stored in harsh conditions for six months, both drugs maintained their stability and structure, suggesting that under more normal temperature conditions, the rings remain viable for a year or even longer. The rings are made of a type of plastic called ethylene-vinyl acetate copolymer (EVA) and share many of the same properties as rings currently used for contraception. They are manufactured using standard processes called hot metal extrusion and injection molding. If clinical trials prove the rings safe and effective, manufacturing and scale-up should be relatively easy, say the researchers who made the rings with the support of the International Partnership for Microbicides located in Silver Springs, Md.
Early studies suggest promise for vaginal tablet containing ARV combination
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Vaginal film with novel dual-action ARV passes early laboratory tests
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Source-Eurekalert
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