Some 40 microbicide products, including those whose active ingredient are ARVs, are currently in development around the world, according to the Alliance for Microbicide Development. Of these, 10 products have been shown to be safe and effective in animal trials and are being tested in humans in the U.S., Africa and India, according to the Center for AIDS Programme of Research (CAPRISA) in Congella, South Africa.
The ARV drug that holds the most promise is tenofovir, an RTI manufactured under the brand name Viread by Gilead Sciences. It is best known as the combination therapy pill, Truvada. The U.S. National Institutes of Health (NIH) and CAPRISA are set to conduct separate human trials of oral and topical tenofovir. NIH is currently recruiting up to 4,200 high-risk women (it hasn't yet said where) to test the gel and pill forms in a two-year trial set to begin in July. The CAPRISA trial of some 1,000 high-risk South African women began in May 2007 and is set to run through the end of next year.
There are about six ARV clinical trials underway in the United States, Africa and India. Among other drugs being tested: Dapivirine and Maraviroc, an RTI and an entry inhibitor, respectively. The International Partnership for Microbicides, a nonprofit drug development group in Silver Springs, Md., is conducting trials on Dapivirine gels and vaginal rings — thin, transparent rings inserted into the vagina that release medications over a month or more. (Vaginal rings are are already available as birth control, such as the product NuvaRing.)
The Partnership's CEO, microbiologist Zeda Rosenberg, says ARVs are promising because they last longer in the body than the compounds used in previous microbicides. The idea is that women could apply an ARV microbicide gel once a day or less and it would still be effective in preventing HIV transmission during a sexual encounter within 12 to 24 hours. To date, the gels tested had to be applied just before sex.
"Early-generation microbicides were coitally dependent, meaning they had to be used just prior to sex," Rosenberg says.
Divorcing microbicide use from sexual activity could help researchers sort out ineffective products from those that simply aren’t being used properly by trial participants. "You cannot watch people apply vaginal microbicide right before they have sex," Harrison says.
They can, however, supervise application in the clinic on a daily basis if the product is longer lasting. A crucial recent development has been production of a gel out of ARVs that could be applied once a day and retains effectiveness regardless of climate. The gels also need to be safe. Some earlier microbicides caused vaginal inflammation. So far, two promising tenofovir gels have been produced, Rosenberg says.
In September, the Contraceptive Research and Development program (CONRAD) in Arlington, Va., a not-for-profit drug research organization affiliated with Eastern Virginia Medical School received a five-year, $100-million grant from the U.S. Agency for International Development (USAID) to test a tenofovir gel, develop new biomarkers (which tell researchers that disease is present so they know if a preventative measure worked to block transmission), and refine mouse modeling for microbicides, which, like most other drugs, are tested on mice and other animals before human trials. But many researchers say these need to be improved.
"Currently there are no markers or models that allow us to predict the safety and efficacy of a microbicide candidate with accuracy," says Henry Gabelnick, executive director of CONRAD. Some scientists are concerned that using ARVs for prevention could increase the spread of HIV resistance, because their use might boost transmission of naturally resistant variants of the disease. For instance, the use of the ARV drug nevirapine to prevent mother-to-child HIV transmission carries the risk of promoting drug-resistant virus.
See what we're tweeting about
7 Comments
Add CommentOn this World AIDS Day --- I am saddened once again to have a major article on microbicides published in an important publication --- that negates, denies, ignores and silences gay men, other men who have sex with men, and the pressing need for rectal microbicides for both women and men.
Reply | Report Abuse | Link to thisAnd it is troubling to see the term microbicide as being something only applied vaginally to protect against HIV. This is very narrow, and therefore, incorrect. Microbicides are being studied for both vaginal AND rectal application - to protect during vaginal intercourse as well as anal intercourse.
Men who have sex with men around the world are 19x more likely to be HIV+ in comparison to the general population. Do they not deserve a mention as being an important population who could benefit from microbicides? Millions and millions of men are already infected, and many millions more are at risk.
There is a significant amount of research dedicated to the development of safe, EFFECTIVE, and acceptable rectal microbicides. Considering unprotected anal intercourse is a common behavior among HUMANS (women included), and considering that it is much more efficient at transmitting HIV compared to unprotected vaginal intercourse (5 to 80 times more so), does it not deserve a couple of words in this article?
To learn more about rectal microbicides - including scientific endeavors and advocacy efforts - please visit the home of IRMA - International Rectal Microbicide Adocates - http://www.rectalmicrobicides.org
Thank you,
Jim Pickett, IRMA Chair
Jim, in the eyes of much of this country, HIV is "gods way of punishing homosexuality." I understand not wanting to see real issues as well as your organizations good work sidestepped, but you could also be glad to see articles that make clear that it's not a "gay" a problem. Not that I'd expect to see those people reading articles on a science website, but....
Reply | Report Abuse | Link to thisI think it's interesting, though, that those religious radicals wound up coincidentally close to the mark. Diseases aren't Gods way of punishing groups of people whose behavior it doesn't like, they're Natures way of keeping populations in check. Every year, it becomes clearer and clearer that the most critical problems we face stem from overpopulation, and as our population happily spirals out of whack unsustainably, (thanks in no small part to those very same religions urging uncontrolled breeding) HIV performs a definite biological function. With the big picture in mind, it is even more unfortunate that homosexual couples are suffering from HIV, as it's been shown over the years that homosexuality is an effect of, and part of the solution to overpopulation.
Gay men, and other men who have sex with men, are in fact, on average, 19 times more likely to be HIV positive compared to the general population ---- a GLOBAL statistic. It is not only a "gay" problem, but HIV among gay men and other men who have sex with men has, sadly, been silenced, denied and negated in much of the world. And millions are dying because of it.
Reply | Report Abuse | Link to thisSee http://irma-rectalmicrobicides.blogspot.com/2008/11/oh-humanity.html
See http://irma-rectalmicrobicides.blogspot.com/2008/08/piot-rails-against-homophobia-at-aids.html
See http://irma-rectalmicrobicides.blogspot.com/2008/08/global-aids-prevention-gives-short.html
Hot Black, you really need to provide some evidence for this outrageous statement: "in the eyes of much of this country, HIV is "gods way of punishing homosexuality." Which country are you talking about? How many is much? A majority? It would be great to know where you get your information or is it just your opinion?
Reply | Report Abuse | Link to thisIt is true that a significant number of Americans view homosexuality as a sin deserving punishment like AIDs. I wouldn't say the majority, but enough to make a difference. I've been to almost every state in this nation and I have found anti-homosexuality sentiments almost everywhere (not always from radicals, not always from conservatives). I think it good that the scientific community doesn't advertise their work towards helping gay men with AIDs. The sad truth is that scientific research requires funding, and taking on something like HIV requires emense funding the likes of which can only come from governements and very wealthy philanthropists. It would be best for everyone if the controversy associated with homosexuality were kept at the edge of the disscussion. Once we find effective treatments and possibly cures or vacines, we can take that knowledge and apply it to homosexual men. It's not that we don't care about the gay men of the world, it's that the best way to help them is to approach the problem with minimal participation from them.
Reply | Report Abuse | Link to thisThere are many natural ways to rid your body of HIV. In contrast with the traditional antiviral cocktails of medicine today, which cost thousands, have severe side effects, and comes with the double edged sword delema,meaning if the virus doesn’t kill you the cocktails will, this medicine is all natural.Please visit this site for the full information about this subject……http://pushgood-nomorehiv.blogspot.com/
Reply | Report Abuse | Link to thishi ! thanks for sharing this informative post.
Reply | Report Abuse | Link to thishttp://simplestdtesting.com/resources