mavacamten will minimize the extent or influence of ethinylestradiol by impacting hepatic/intestinal enzyme CYP3A4 metabolism. Prevent or Use Alternate Drug. Progestin and ethinyl estradiol are CYP3A4 substrates. Mavacamten may decrease systemic exposures of ethinyl estradiol and progestin, which may lead to contraceptive failure or a rise in break