Transdermal ethinylestradiol/norelgestromin: a review of its use in hormonal contraception.

UNLABELLED

Ethinylestradiol 20 microg/day plus norelgestromin 150 microg/day have been formulated into a transdermal patch for hormonal contraception. The predominant mechanism of action for transdermal ethinylestradiol/norelgestromin (Ortho Evra, Evra) is inhibition of ovulation by suppression of gonadotropins. It suppresses follicular development, induces changes to the endometrium that reduce the probability of implantation, and increases the viscosity of cervical mucus, which may prevent sperm penetration into the uterus. Two large randomized, nonblind efficacy studies demonstrated that transdermal ethinylestradiol/norelgestromin was as efficacious in preventing pregnancy as oral triphasic ethinylestradiol/levonorgestrel or oral ethinylestradiol/desogestrel. A large, noncomparative study also showed transdermal ethinylestradiol/norelgestromin to have good contraceptive efficacy. Moreover, in the two comparative trials, women using transdermal ethinylestradiol/norelgestromin had higher rates of perfect compliance than women using oral contraception. Age did not affect the rate of perfect compliance in women using the transdermal ethinylestradiol/norelgestromin patch, whereas the rate of compliance reduced with younger age in oral contraceptive users. Pooled results from three efficacy studies found that 1.8% of patches were replaced as a result of complete detachment and 2.9% because of partial detachment. Physical exercise, water immersion, and living in a humid climate did not affect patch adhesion. Transdermal ethinylestradiol/norelgestromin was generally well tolerated in clinical trials. The most common menstrual disturbances were breakthrough bleeding/spotting and dysmenorrhea. The incidence of discontinuation of treatment because of an adverse event was < or = 3.2%, with the most common reason being application-site reactions.

CONCLUSIONS

Transdermal ethinylestradiol/norelgestromin offers a well tolerated, effective, reversible, and easy-to-use method of hormonal contraception with an increased likelihood of compliance relative to oral contraceptives.