implanon and Grisactin ultra Interactions

Interactions between implanon(etonogestrel) and Grisactin ultra (griseofulvin)

griseofulvin and etonogestrel (Major Drug-Drug)

ADDITIONAL CONTRACEPTION RECOMMENDED: Limited clinical data suggest that griseofulvin may reduce the efficacy of contraceptive hormones. There have been case reports of menstrual abnormalities (e.g., breakthrough bleeding, amenorrhea, irregular menses) or unintended pregnancy following the addition of griseofulvin in patients receiving long-term oral contraceptives. The proposed mechanism is accelerated clearance of the hormones due to induction of hepatic CYP450 enzymes by griseofulvin.

MANAGEMENT: Women using low-dose hormonal contraceptives should be advised of the risk of breakthrough bleeding and unintended pregnancy during concomitant therapy with griseofulvin. Because griseofulvin has been shown to be teratogenic in animal studies and is capable of inducing aneuploidy (abnormal segregation of chromosomes following cell division) in mammalian cells in vitro and in vivo, it is particularly important that patients not become pregnant during treatment. Therefore, additional methods of birth control should be used during and for one month after griseofulvin therapy. Input from a gynecologist or similar expert on adequate contraception should be sought as needed. Intrauterine systems are unlikely to be significantly affected because of their local action.