Implanon: a critical review.
OBJECTIVE
To evaluate clinical information on Implanon as a long-term method of contraception and, specifically, to review the efficacy and adverse effect profile of Implanon.


METHODS
A MEDLINE search (from 1966 through June 1999) was performed to retrieve primary and review articles. The search was limited to data on human subjects. Some references were identified through secondary sources.


METHODS
Pharmacokinetic and pharmacodynamic studies, and clinical trials assessing the efficacy and safety of desogestrel implants were reviewed. Relevancy and consistency of information was assessed for each trial.


RESULTS
Implanon is the newest contraceptive implant system that has completed worldwide Phase III clinical trials. It is a single rod that contains a core of 68 mg of 3-keto-desogestrel with a membrane of ethylene vinyl acetate. Inhibition of ovulation occurs within one day of implantation, and effective contraception lasts for three years. Fertility returns within one month after implant removal. Insertion and removal by trained medical professionals is simple, and only minor complications have been documented. Adverse effects are mild and primarily consist of abnormal bleeding, weight gain, acne, breast pain, and headache.


CONCLUSIONS
The data on Implanon indicate that it provides effective long-term contraception with limited adverse effects. It appears to be a good addition to the currently available contraceptives.
School of Pharmacy, University of California at San Francisco, 94143-0622, USA.
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D000328:Adult; D002986:Clinical Trials as Topic; D003271:Contraceptive Agents, Female / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics / Q000494:pharmacology*; D000075202:Contraindications; D017135:Desogestrel; D005260:Female; D006801:Humans; D011247:Pregnancy; D014753:Vinyl Compounds / Q000008:administration & dosage / Q000009:adverse effects / Q000493:pharmacokinetics / Q000494:pharmacology*
D003271:Contraceptive Agents, Female; D014753:Vinyl Compounds; C044815:etonogestrel; D017135:Desogestrel