Enzyme induction occurs when chemicals cause an increase in synthesis and activity of enzymes, thereby increasing the metabolism of drugs that are catalyzed by those enzymes.
When one drug causes an increased rate of metabolism of another drug by inducing the CYP enzyme involved in the biotransformation of that drug, there is a resultant effect on the drug’s efficacy. The parent drug is metabolized at an accelerated rate, leading to low potency and reduced effect. In cases where a CYP enzyme catalyzes the conversion of a less active parent (prodrug) to a more active metabolite, induction could be responsible for increasing active metabolite levels to potentially toxic levels.