Pharmacokinetic Interaction Between Nevirapine and Ethinyl Estradiol/Norethindrone When Administered Concurrently to HIV-Infected Women.

Mildvan, Donna; Yarrish, Robert; Marshak, Ann; Hutman, Herbert W.; McDonough, Marita; Lamson, Michael; Robinson, Patrick
JAIDS Journal of Acquired Immune Deficiency Syndromes:
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Objective: To determine the effects of nevirapine (NVP), a nonnucleoside reversetranscriptase inhibitor of HIV-1 and P450 inducer, on the pharmacokinetics (PK) of ethinyl estradiol (EE)/norethindrone (NET), a widely used oral contraceptive, and to assess the effects of EE/NET on the steady-state PK of NVP.

Methods: Ten HIV-1-infected women underwent intensive PK sampling after single-dose administration of EE/NET (days 0-1). Oral NVP 200 mg once daily (days 2-15), followed by 200 mg twice daily (days 16-29), was added to background potent antiretroviral therapy. On day 30, intensive PK sampling was performed after concurrent administration of NVP 200 mg and a single dose of EE/NET.

Results: Concomitant administration of NVP at steady state with EE/NET resulted in a significant (29%) median reduction in the area under the plasma concentration time curve (AUC[infinity]) and a significant reduction in mean residence time (MRT) and half-life (t1/2) of EE. There was a significant (18%) median reduction in the AUC[infinity] for NET that was not associated with a detectable change in NET Cmax, MRT, or t1/2.

Conclusion: Oral contraceptives should not be the primary method of birth control in women of child-bearing potential who are treated with NVP.

(C) 2002 by Lippincott Williams & Wilkins