Enzyme Induction

The process by which a drug increases the synthesis or activity of drug-metabolizing enzymes, particularly cytochrome P450 isoforms, leading to enhanced metabolism of substrate drugs. Induction typically requires days to weeks to reach full effect as it depends on new protein synthesis. The result is decreased plasma concentrations of affected drugs and potential therapeutic failure.

Exemples

• Rifampin: potent inducer of CYP3A4, reduces efficacy of oral contraceptives
• Carbamazepine: induces CYP3A4 and CYP1A2, also undergoes autoinduction
• St. John's Wort: induces CYP3A4 via PXR activation, reduces cyclosporine levels