Oral contraceptive failure can occur with:
Rifampicin is a Microsomal enzyme inducer. It enhances the metabolism of oral contraceptives and cause failure. other enzyme inducers are phenytoin, phenobarbitone, carbamezipine, smoking, st john's wa- they can also cause contraceptive failure (REF.Essential of medical pharmacology K D TRIPATHI 6 Edition, Page No -741)
Ketoconazole
Aminoglutethimide
metyrapone
Glucocoicoids
Endocrinology