Drug Interactions between cobicistat and medroxyprogesterone

ADDITIONAL CONTRACEPTION RECOMMENDED: Coadministration with cobicistat and elvitegravir may alter the plasma concentrations of contraceptive hormones. The exact mechanism of interaction has not been described. In 13 study subjects, administration of ethinyl estradiol 0.025 mg and norgestimate 0.18 to 0.25 mg once daily in combination with elvitegravir 150 mg plus cobicistat 150 mg once daily decreased the mean ethinyl estradiol peak plasma concentration (Cmax), systemic exposure (AUC) and trough plasma concentration (Cmin) by 6%, 25% and 44%, respectively. In contrast, norgestimate Cmax, AUC and Cmin increased by 2.08-, 2.26- and 2.67-fold, respectively. Clinical effects of increased progestogen levels are not fully known, but may include increased risk of insulin resistance, dyslipidemia, acne, and venous thrombosis.

MANAGEMENT: The potential risks and benefits of using norgestimate-containing contraceptives in combination with cobicistat and elvitegravir should be considered, particularly in women who have risk factors for insulin resistance, dyslipidemia, acne, and venous thrombosis. Coadministration of cobicistat and elvitegravir with other hormonal contraceptives (e.g., contraceptive patch, contraceptive vaginal ring, or injectable contraceptives), oral contraceptives containing progestogens other than norgestimate, or less than 25 mcg of ethinyl estradiol has not been studied and is not recommended. Some authorities recommend that hormonal contraceptives containing at least 30 mcg of ethinyl estradiol with norgestimate should be used in combination with the multi-ingredient antiretroviral formulations containing elvitegravir/cobicistat/emtricitabine/tenofovir disoproxil fumarate or elvitegravir/cobicistat/emtricitabine/tenofovir alafenamide. However, the long term effects of increased progesterone exposure are not known. Alternative, nonhormonal methods of contraception may be considered.