Because rifampin potently induces CYPs 1A2, 2C9, 2C19, and 3A4, its administration results in a decreased t1/2 for a number of compounds, including: HIV protease and non-nucleoside reverse transcriptase inhibitors Digitoxin Digoxin Quinidine Disopyramide Mexiletine Tocainide Ketoconazole Propranolol Metoprolol Clofibrate Verapamil Methadone Cyclosporine Coicosteroids Coumarin anticoagulants Theophylline Barbiturates Oral contraceptives Halothane Fluconazole Sulfonylureas It leads to therapeutic failure of these agents, with potentially catastrophic consequences. Ref: Gumbo T. (2011). Chapter 56. Chemotherapy of Tuberculosis, Mycobacterium Avium Complex Disease, and Leprosy. In L.L. Brunton, B.A. Chabner, B.C. Knollmann (Eds), Goodman & Gilman's The Pharmacological Basis of Therapeutics, 12e.