Question

Which antitubercular drug inhibits the action of OCPs?

• A. Rifampicin
• B. Ethambutol
• C. Isoniazid
• D. Pyrazinamide

Answer 1

The Correct Option is A

To determine which antitubercular drug inhibits the action of oral contraceptive pills (OCPs), we need to understand the interaction between these drugs and enzyme induction pathways in the liver.

Rifampicin, a commonly used antitubercular drug, is known to be a potent inducer of cytochrome P450 (CYP) enzymes, specifically CYP3A4. This enzyme induction increases the metabolism of various drugs, including the hormones found in oral contraceptives. As a result, the effectiveness of the OCPs is reduced, which may lead to contraceptive failure.

In contrast, Ethambutol, Isoniazid, and Pyrazinamide do not have significant enzyme-inducing effects and thus do not notably affect the efficacy of oral contraceptives.

Therefore, the drug that inhibits the action of OCPs by inducing their metabolism is Rifampicin.