Population Council Research that makes a difference

The Population Council and Antares Pharma, Inc., are developing a contraceptive gel that can be absorbed through the skin of a woman's arm, leg, or abdomen. The gel contains the progestin Nestorone® and a form of estrogen, called estradiol, that is chemically identical to the estrogen made by a woman’s body. There are several indications from previous research that using Nestorone in combination with a natural estrogen (such as estradiol) in a transdermal formulation may result in a contraceptive method with fewer side effects than experienced with currently available methods.

Previous studies identified an effective dose of the two hormones that consistently resulted in blood levels that would be expected to provide effective contraception and to maintain a woman’s normal estrogen levels and bleeding patterns. In 2008, the Council and Antares launched a Phase 2 trial to determine the lowest safe and effective dose to suppress ovulation. In past studies, the gel was well tolerated, with no serious adverse events recorded. Previous studies also showed that women using Nestorone experience fewer side effects, such as acne, weight gain, and altered cholesterol levels, that are often experienced by women who use other common progestins.

Nestorone is a novel synthetic progestin that is highly effective at stopping ovulation at a low dose. It has no androgenic hormonal effects, and has a good safety profile. It is not active when taken orally and is therefore especially appropriate for topical application as well as for use during breastfeeding. Previous studies with Nestorone delivered via implants in women who were breastfeeding did not show any health impact on the infants.

The Nestorone/estradiol contraceptive gel offers a needed and potentially attractive contraceptive option. The formulation, the active compounds, and the drug-delivery system are all designed to reduce the serious side effects sometimes seen with current contraceptive methods, potentially increasing women’s ability and desire to continue using the method.

The gel formulation is also suitable for hormone therapy.

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Related project

• Transdermal Delivery Systems for Women: Spray-on Contraceptive