mavacamten will lessen the extent or impact of ethinylestradiol by impacting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Progestin and ethinyl estradiol are CYP3A4 substrates. Mavacamten could reduce systemic exposures of ethinyl estradiol and progestin, which can produce contraceptive failure or an increase in breakth