Clark was part of a team led by biomedical engineer Patrick Kiser, who has been working on the ring for about five years. Kiser recently left the U. for Northwestern University.
A small clinical trial is slated to begin soon to test the safety of the ring, which will be followed by a larger trial, Clark said.
One of the co-authors on the paper is David Friend, a product development director at CONRAD, a company that develops reproductive health products for developing countries and funded the research through an agreement with the U.S. Agency for International Development.
Though previous studies have shown antiretroviral drugs can prevent HIV infection, they have to be taken every day at high doses, and Friend said a ring could help more people get the medication regularly.
"Products only work when they are used," he said in a statement from Northwestern.
The 5.5 centimeter-ring delivers two drugs. Tenofovir is a common anti-HIV drug that could also protect against herpes, Clark said. Levonorgestrel is the same contraceptive that's used in a long-lasting intrauterine device (IUD) called Mirena.
To create the ring, scientists had to overcome the different nature of the two drugs tenofovir is very water-soluble while levonorgestrel isn't as well as different dosages. Users need about 1,000 times more tenofovir than the birth-control drug.
"A lot of engineering has gone into developing the ring," Kiser, the senior author on Wednesday's study, said in a statement.
The portion of the ring that releases the antiretroviral is made of one kind of polyurethane while the contraceptive section is made from another type, with a third variety in between to keep them separate.
"This is kind of a new idea, leveraging this delivery platform and the clinical evidence that we can prevent infection through the preventive administration of an HIV drug," said Clark. "It's a long-term effort to get something like this from the bench to the first human study and eventually to market."