October 17, 2012
Researchers have been delving into new human immunodeficiency virus (HIV) prevention technology. A joint effort by the University of Utah and CONRAD has resulted in the development of an intravaginal ring that can be utilized by women to stop the transmission of HIV through sex. Scientists believe that it is the first product that allows for the vaginal delivery of tenofovir in a long-lasting method.
Scientists at the University of Utah collaborated with CONRAD, a division of the Department of Obstetrics and Gynecology at Eastern Virginia Medical School in Virginia that focuses on reproductive health research and contraceptive development. In the study, the ring was used with sheep to test whether the release of the antiretroviral drug tenofovir was effective and safe during a 90-day period. Tenofovir is considered the only topical prophylactic that can lower the sexual transmission of HIV. Besides being presented at the 2012 American Association of Pharmaceutical Scientists (AAPS) Annual Meeting and Exposition in Chicago, the results of the study will be published in the 12th issue of Antimicrobial Agents and Chemotherapy.
“We have developed a new intravaginal ring technology based on rubbery hydrogel plastics that are loaded with antiretroviral drugs. We can engineer the plastic so it can release a small quantity of drug per day, or a much larger quantity, depending on the drug being delivered,” explained the study’s lead investigator Patrick Kiser, a researcher at the University of Utah, in a prepared statement.
In the past, vaginal rings have been used to help decrease HIV infection. Recent advancement in materials and technologies has led to progress in the development of the contraceptive option.
“Most vaginal rings release a limited quantity of drug each day, but this ring can release quantities 1,000 times larger due to the selection of specific hydrophilic polymers with high permeability,” commented one of the study’s authors David Friend, Ph.D., the director of Product Development at CONRAD, in the statement. “This study showed that the ring releases at least 10 mg of tenofovir a day over 90 days, which makes it very possible that it can be effective in preventing HIV infection in women.”
The researchers believe that the ring must be worn for 90 days to be effective. The intravaginal ring is composed of rubbery water sealable plastics with tubing made up of plastic that is filled with tenofovir and glycerin. The tube is then closed up and formed into a ring shape. In the center of the ring lies glycerol, which helps bring liquid from the vagina and quickens the delivery of the drug.
“We directly compared the ring to 1 percent tenofovir gel, and the ring resulted in similar, if not higher, levels of drug in the vaginal tissue,” continued Friend in the statement. “If the results in sheep hold up in humans, we would expect this ring to be highly protective against HIV.”
The team of investigators noted that the ring could also be adapted to deliver an anti-HIV agent along with a contraceptive. As such, it is considered a multi-purpose prevention technology. The group plans to push the product into the first clinical trial next year.
“We anticipate that this next-generation ring will be able to release a spectrum of drugs that currently cannot be delivered due to limitations of standard technology,” concluded Kiser in the statement. “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.”