As a vaginal gel, the antiretroviral tenofovir can protect women against being infected with HIV during sex, but it needs to be used every time. To get around any problems with compliance, a team from the University of Utah and the reproductive health research organization CONRAD are developing a vaginal ring that can be left in place and deliver tenofovir gradually over 90 days, which could give women long-term protection against HIV infection.
Treatments for HIV have improved vastly since the approval of the first antiretroviral in 1987, with many people treated with combinations of drugs living with almost undetectable levels of virus in their blood. However, the ideal is stopping infection in the first place. Condoms are the simplest method, and antiviral gels, such as tenofovir gel, have also been effective. But these are not always available, and in some environments and situations may not be convenient or acceptable.
The ring, presented at the 2012 American Association of Pharmaceutical Scientists (AAPS) Annual Meeting and Exposition, is made of plastic tubing filled with a paste of tenofovir; these are simple to make and hundreds can be produced a day in a semi-automated process. The tubing absorbs water when inserted high into the vagina, releasing the drug.
Patrick Kiser, who led development of the ring at the University of Utah, presented research in sheep at the meeting--the ring delivered levels of drug high enough to be able to reduce the risk of HIV infection in women. The ring could also deliver hormones, and a combined contraceptive and anti-HIV ring is currently in development.
"This ring is a breakthrough design because it is highly adaptable to almost any drug; the amount of drug delivered each day is the same and the release rate can be modified easily if needed," said Kiser.
While this is still in early development, a ring that delivers an anti-HIV agent as well as other drugs such as contraceptives and can be left in for extended periods could offer long-term protection for women, preventing infection and saving lives, as well as reducing the risk of transmission throughout the community.
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- see the abstract (PDF)