Osmifen Ospemifene Ketoconazole
ModerateKetoconazole is a strong CYP3A4 inhibitor, and when it is taken with ospemifene it increases the body's exposure to ospemifene by 1.4-fold. The leaflet also notes that drugs which speed up CYP3A4, CYP2C9 and/or CYP2C19 activity, such as rifampin, would be expected to lower the exposure to ospemifene, which may reduce its clinical effect.
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.