Times of India
26 May 2010
By Kounteya Sinha
New Delhi, India
The HIV virus is unique and requires equally novel interventions. Scientists are, therefore, working on various out–of–the–box drug delivery systems to protect women against HIV.
Imagine a cello tape–like film that once inserted in the vagina would melt away and disperse drug to cells to protect against HIV. Or maybe a flexible vaginal ring containing two anti–HIV drugs. How about an almond–shaped vaginal tablet that would dissolve and deliver sustained levels of anti–HIV drugs over several hours.
All these products have now passed initial trials, according to scientists who presented their early findings at the International Microbicides Conference in Pittsburgh over the weekend.
Most of the world’s women do not control when, with whom and with what protection, if any, they have sexual relations. This powerlessness is most acute in developing countries where HIV prevalence is highest. Women’s most urgent need is for a prevention technology which they control themselves. In the absence of a vaccine against HIV, microbicides –chemical agents used typically by women within the vagina in order to prevent infection by HIV –are the answer.
However, most of the research on microbicides till now, has focused on gels or vaginal creams. But till now, the world has failed to create a successful microbicide. In February 2007, trials of a cellulose sulphate called Ushercell was stopped ahead of schedule for failing to work. In 2008, Carraguard, a vaginal cream that was the first to make it through late–stage testing, failed.
It was unable to prevent transmission of the AIDS virus. Meanwhile, the conference in Pittsburg has provided fresh hope. Scientists announced that the intra–vaginal ring formulated with two anti–HIV drugs dapivirine and maraviroc was found to deliver therapeutic levels of both drugs for as long as a month. Rings can be used for a long time as against gels that must be used every day or at the time of sex.
Researchers also announced the development of an almond–shaped vaginal tablet that delivered sustained levels of anti–HIV drugs over 12 hours. The vaginal tablet is based on a pharmaceutically acceptable bio–adhesive polymer that binds to the moist lining inside the vagina, allowing the drug to transfer to key cells that comprise the epithelium.
The vaginal film works by preventing HIV from entering a cell and inhibiting its activity. Researchers reported that they had developed a film smaller than a stick of gum and as thin as a sheet of paper. Laboratory tests indicated it was potent against HIV, non–toxic to cells and it could dissolve quickly to release nearly all the compounds. All these new options were tried out in conjunction with the International Partnership for Microbicides. Of the 2.5 million people estimated to be infected with HIV in India, nearly 39% are women, with heterosexual transmission causing 85% of new infections.
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