Title: Subdermal contraceptive implants.

POPLINE Document Number: 108732

Author(s):

Peralta O
Diaz S
Croxatto H

Source citation:

JOURNAL OF STEROID BIOCHEMISTRY AND MOLECULAR BIOLOGY, 1995 Jun;53(1-6):223-6.

Abstract:

Subdermal contraceptive implants deliver progestin from polymer capsules or rods placed under the skin. Diffusing slowly from the polymer containers at a stable rate, the hormone provides contraception for 1-5 years, with the period of protection conferred dependent upon the specific progestin and type of polymer employed. Once inserted, the device allows a woman to have sexual intercourse over a certain period of time without any significant risk of becoming pregnant. Protection is ensured with a low drug dosage and no estrogen, and fertility is readily reversible once the implants are removed. The levonorgestrel implant Norplant R is the only subdermal contraceptive implant system approved for distribution. Annual pregnancy rates using Norplant are extremely low. Menstrual problems are the main reason why women discontinue using Norplant. Research is ongoing to reduce the number of implanted units and to introduce other progestins which may minimize side effects. Norplant-2 was designed to release the same dose of progestin from only two covered rods. Nestorone, 3-Keto-desogestrel, and Uniplant are single implants under development which are expected to be effective for 1-2 years. Completed phase II clinical trials with Nestorone found no pregnancies in 1570 woman-months of use, although bleeding irregularities occurred in 20-30% of women. A multicenter study is ongoing with a newly-designed 3-keto-desogestrel implant named Implanon, as well as another multicenter study with Uniplant, an implant which releases nomegestrol acetate with a one-year duration of action.

Keywords:

Contraceptive Implants
Levonorgestrel
Contraception Research
Contraceptive Methods
Contraception
Family Planning
Contraceptive Agents, Progestin
Contraceptive Agents, Female
Contraceptive Agents