Loperamide + Simethicone Ketoconazole
ModerateKetoconazole slows down the body's processing of loperamide. It blocks CYP3A4, an enzyme that breaks loperamide down, and P-glycoprotein, a carrier that pushes it out of the body. In a study, people took a single 16 mg dose of loperamide along with ketoconazole. The loperamide level in their blood rose about 5 times higher than usual. Even with this big rise, the study found no stronger drug effect. This was checked with pupillometry, a test that measures the size of the pupil in the eye.
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.