mavacamten will lower the level or outcome of ethinylestradiol by influencing hepatic/intestinal enzyme CYP3A4 metabolism. Stay away from or Use Alternate Drug. Progestin and ethinyl estradiol are CYP3A4 substrates. Mavacamten could lower systemic exposures of ethinyl estradiol and progestin, which may bring about contraceptive failure or a rise in