Enzyme inducer

An enzyme inducer is a type of drug that increases the metabolic activity of an enzyme either by binding to the enzyme and activating it, or by increasing the expression of the gene coding for the enzyme.

Classic examples: barbiturates (phenobarbitone), antiepileptics and rifampin. Carbamazepine is another enzyme inducer. By enzyme induction it can reduce efficacy of haloperidol and oral contraceptives.