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A new product has the potential to protect people from acquiring the human immunodeficiency virus (HIV), an incurable infection most commonly transmitted via sex. According to a study conducted on pig-tailed macaque monkeys, a novel intravaginal ring mixed with anti-retroviral drug tablets can be an effective tool for HIV prevention. When implanted, the ring was capable of releasing the drug safely over the course of 28 days.

"The ring maintained steady state drug levels in the vaginal tissues, the key anatomic compartment for preventing sexual HIV transmission, and eliminated the concentration troughs encountered with oral medications," said corresponding author, Marc Baum reported in the press release. "This should boost effectiveness."

For this study conducted by James M Smith's group at the Centers for Disease Control and Prevention (CDC) in Atlanta, GA, the researchers tested two drug combinations, which were Truvada (emtricitabine and tenofovir disoproxil fumarate) and Truvada mixed with maraviroc. They found that the ring's topical drug delivery was effective in administering the drug. Often times with oral therapy, people can forget to take their medications, which can jeopardize their health.

"Issues such as adherence to a regular dosing schedule are significantly reduced by continuous release of the drugs into the vaginal mucosa independently of coitus and daily dosing," Baum said. "In addition, systemic levels are so low as to usually be undetectable in topical delivery. That means that side effects are dramatically reduced, or eliminated entirely."

The ring is made with an impermeable elastomer scaffold. On the scaffold, the researchers had placed the polymer-coated drug tablets. When the ring is implanted inside the vagina, the drugs get transferred directly to the vaginal mucosa, which then connects the drug pods with vaginal fluids.

The researchers chose to use pig-tailed macaque monkeys because they have a very similar menstrual cycle to humans. The monkeys also have similar vaginal architecture and vaginal microbiome.

The study was published in the journal, Antimicrobial Agents and Chemotherapy.