mavacamten will decrease the level or influence of ethinylestradiol by impacting hepatic/intestinal enzyme CYP3A4 metabolism. Avoid or Use Alternate Drug. Progestin and ethinyl estradiol are CYP3A4 substrates. Mavacamten may possibly lower systemic exposures of ethinyl estradiol and progestin, which may bring on contraceptive failure or a rise in b