Interactions between ethinyl-estradiol(ethinyl estradiol) and Amprenavir (amprenavir)
ethinyl estradiol and amprenavir (Major Drug-Drug)
GENERALLY AVOID: Coadministration with some hormonal contraceptives may decrease the plasma concentrations of amprenavir. The mechanism of interaction is unknown. In 10 study subjects coadministered amprenavir (1200 mg twice a day for 28 days) and ethinyl estradiol-norethindrone (0.035 mg-1 mg for 1 cycle), amprenavir systemic exposure (AUC) and trough plasma concentration (Cmin) were reduced by 22% and 20%, respectively, compared to administration of amprenavir alone. Conversely, the Cmin of ethinyl estradiol was increased by 32%, while the Cmin and AUC of norethindrone were increased by 45% and 18%, respectively.
MANAGEMENT: Given the risk of reduced viral susceptibility and resistance development associated with subtherapeutic antiretroviral drug levels, alternative (i.e., nonhormonal) methods of birth control should be considered in patients treated with amprenavir.
