FRED H. BIXBY
FELLOWSHIP PROGRAM
Mentor Research Interests

Régine L. Sitruk-Ware, M.D.

Our research on reproductive health at the Population Council includes discovering new targets for contraceptives and developing new methods with added medical benefits and safer profiles than existing methods. Our major objectives are (1) to offer men and women new contraceptive options that are affordable and easy to use and (2) to improve compliance and acceptability of contraceptive methods.

The contraceptive efficacy of the new long-acting methods such as implants, rings, and transdermal patches, now available, is the highest among contraceptives as they do not rely on daily compliance. Therefore long-acting delivery systems are being developed for various durations of use.

Work is progressing on the following new options that would bring additional health benefits to users:

• A vaginal ring delivering 150 µg/day of Nestorone®, a nonandrogenic 19-norprogesterone derivative, and 15 µg/day of ethinyl estradiol over 12 months;
• Progesterone receptor modulators (PRMs) delivered through a three-month vaginal ring and an intrauterine system;
• Dual-protection methods (contraception and HIV prevention) tested as vaginal gels;
• Transdermal gels or spray (i.e., metered-dose transdermal system [MDTS]) using Nestorone and estradiol rather than ethinyl estradiol; and
• For men, new tissue-selective androgens, without action on the prostate, . New specific targets also are being studied to develop nonhormonal methods for male contraception. In our aim to discover new leads for hormonal and nonhormonal male methods, we are also studying several approaches to decrease sperm-fertilizing capabilities with potential noncontraceptive health benefits.

The safety of new contraceptives is of paramount importance. Studies are needed to determine first in animals that the administration of new molecules is devoid of unwanted effects. In addition, if failures occur during use of a method, exposure of the embryo to these molecules may be harmful. It is our task also to study these aspects of toxicity with all the products we are developing before beginning clinical studies. Our pharmacology and toxicology laboratories also address this aspect of the research and development of new methods.

Improved access to existing methods and expansion in countries where they are not yet available is also a major need. It is our objective to expand access to safe and effective methods and help to transfer our technologies to different geographic areas.

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