Osmifen Ospemifene Rifampicin
ModerateRifampicin is a strong CYP3A4 inducer and a moderate CYP2C9 and CYP2C19 inducer, and it lowers the amount of ospemifene in the body by 58%. So taking ospemifene with rifampicin, or with other medicines that speed up CYP3A4, CYP2C9 and/or CYP2C19 in the same way, is expected to reduce how much ospemifene reaches the blood, and this may make ospemifene work less well.
These medicines are often taken together with some care. Your doctor may change a dose, space them apart or check on you more often. Make sure your doctor and pharmacist know you take both.