mavacamten will reduce the extent or effect of ethinylestradiol by impacting hepatic/intestinal enzyme CYP3A4 metabolism. Keep away from or Use Alternate Drug. Progestin and ethinyl estradiol are CYP3A4 substrates. Mavacamten may minimize systemic exposures of ethinyl estradiol and progestin, which can bring on contraceptive failure or an increase