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