Oral contraceptives are not given with:: (A) Streptomycin, (B) Gresiofulvin, (C) Pyraziniamide, (D) Ethambutol
Answer is B. Griseofulvin is an enzyme inducer which increases the metabolism of the oral contraceptives and thus causes its failure. (Ref.Essentials of medical pharmacology TD Tripathi 7th edition page no.326.)