(HealthDay News) – An intravaginal ring containing drugs to prevent HIV transmission as well as pregnancy is able to deliver the drugs at effective levels for 90 days, according to a study presented at the annual meeting of the American Association of Pharmaceutical Scientists, held from Nov. 10–14 in San Antonio.

Patrick Kiser, PhD, from the University of Utah in Salt Lake City, and colleagues designed an intravaginal ring using reservoir-type polyurethane segments. The segments were individually optimized to deliver a high flux of tenofovir (the only topical HIV transmission prophylactic effective in gel form) and a low flux of levonorgestrel (a contraceptive). The intravaginal ring was tested by in vitro release testing and three-month pharmacokinetics studies in rabbits and sheep.

The researchers found that levels of the two drugs were time-independent and tunable, and were optimized to a target of 10mg/day tenofovir and 10 or 20µg/day levonorgestrel. Local levels of tenofovir in the target tissue were similar or higher than the levels following application of a 1% tenofovir gel. The release of levonorgestrel was consistent with levels known to be efficacious in women.

“We developed a unique intravaginal ring technology that met our product objectives of delivering a high flux of a hydrophilic antiretroviral (tenofovir) with a low flux of a hydrophobic contraceptive (levonorgestrel) in a controlled, time-independent manner for 90 days,” Kiser and colleagues conclude.

Several authors are employees of CONRAD, which is contributing to the development of the intravaginal ring.

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