Schöller-Gyüre M, Kakuda TN, Woodfall B, Aharchi F, Peeters M, Vandermeulen K, Hoetelmans RM
Effect of steady-state etravirine on the pharmacokinetics and pharmacodynamics of ethinylestradiol and norethindrone. [Journal Article, Research Support, Non-U.S. Gov't]
Contraception 2009 Jul; 80(1):44-52.
BACKGROUND: Etravirine, a non-nucleoside reverse transcriptase inhibitor (NNRTI) active against NNRTI-resistant HIV, is an inducer of CYP3A4 and an inhibitor of CYP2C9/19.
STUDY DESIGN: The effect of etravirine on the pharmacokinetics and pharmacodynamics of ethinylestradiol and norethindrone was assessed in 30 HIV-negative females. Following a run-in cycle with ethinylestradiol/norethindrone, the pharmacokinetics of ethinylestradiol and norethindrone was assessed on Day 15 of Cycle 2. Etravirine 200 mg bid was coadministered on Day 1 to Day 15 of Cycle 3, with pharmacokinetic assessments of ethinylestradiol, norethindrone and etravirine on Day 15.
RESULTS: When combined with etravirine, the least-squares means (LSM) ratios (90% confidence interval) for ethinylestradiol AUC(24h), C(max) and C(min) were 1.22 (1.13-1.31), 1.33 (1.21-1.46) and 1.09 (1.01-1.18), respectively, compared to administration alone. LSM ratios for norethindrone parameters were 0.95 (0.90-0.99), 1.05 (0.98-1.12) and 0.78 (0.68-0.90), respectively.
CONCLUSION: These changes are not considered clinically relevant. No loss in contraceptive efficacy is expected when coadministered with etravirine.
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