2026 INBDE Pharmacology Practice Test – Complete Exam Prep

The main concept is a pharmacokinetic interaction where one drug alters the body's ability to metabolize another. Lidocaine is cleared mainly by the liver, and its metabolism can be slowed if hepatic blood flow or enzyme activity is reduced. Propranolol, a nonselective beta-blocker, can decrease hepatic perfusion (and can influence liver enzymes), which slows lidocaine metabolism. When breakdown is slowed, lidocaine accumulates, increasing its plasma levels and the risk of systemic toxicity. That’s why the statement that propranolol decreases lidocaine breakdown is the best fit.