Progestin implants.
Progestin implants for contraception are highly effective, safe, and the most convenient choice for many women. Progestin implants currently on the market, preparing for launch, or under investigation are reviewed here. Their basic galenic and pharmacokinetic features, as well as their contraceptive effectiveness, are described. The first progestin-only contraceptive implant placed on the market was Norplant, a multiunit system. Since then, several single- and double-rod implants have been developed, each using one of four different progestins: levonorgestrel, etonogestrel, Nestorone and nomegestrol acetate. Jadelle is similar to Norplant but consists of only two, rather than six, Silastic rods to simplify insertion and removal; nevertheless, levonorgesterel serum levels are identical, and performance is the same for both systems. The single implant systems reviewed here are: Implanon with a 3-year duration; Nestorone implants for breast feeding and non-breast feeding women lasting up to 2 years; and Uniplant, which is effective for 1 year. The advantages and disadvantages of progestin implants, the importance of counseling for increasing user satisfaction, and the future outlook for this contraceptive method are also discussed.
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Instituto Chileno de Medicina Reproductiva, José Victorino Lastarria 29, Depto. 101, Casilla 96 - Correo 22, Santiago, Chile. icmer@huelen.reuna.cl
D000282:Administration, Intravaginal; D003271:Contraceptive Agents, Female / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000592:standards; D003692:Delayed-Action Preparations / Q000493:pharmacokinetics / Q000592:standards; D004343:Drug Implants / Q000493:pharmacokinetics / Q000592:standards; D005260:Female; D006801:Humans; D011247:Pregnancy; D011372:Progestins / Q000008:administration & dosage / Q000493:pharmacokinetics / Q000592:standards*
D003271:Contraceptive Agents, Female; D003692:Delayed-Action Preparations; D004343:Drug Implants; D011372:Progestins