cytochrome P450 inhibition
The process by which certain drugs block the enzymatic activity of CYP450 enzymes, potentially altering the metabolism of co-administered medications.
Full Definition
Cytochrome P450 inhibition occurs when one drug interferes with the metabolic activity of CYP450 enzymes, leading to decreased clearance of substrate drugs. This can result in elevated plasma concentrations and increased risk of toxicity for medications metabolized by the inhibited enzyme. Common CYP450 inhibitors in psychiatry include fluoxetine and fluvoxamine (CYP2D6), while some antifungals and certain antibiotics are potent CYP3A4 inhibitors. Understanding these interactions is crucial for safe prescribing practices and avoiding potentially dangerous drug combinations.
Usage
Usage note: Specify which CYP enzyme when known; distinguish from induction which has opposite effects.
In Context
- "Fluoxetine's potent cytochrome P450 inhibition may necessitate dose reduction of co-administered tricyclic antidepressants." — Drug interaction warning
- "The case report highlighted severe toxicity resulting from cytochrome P450 inhibition by ketoconazole affecting quetiapine metabolism." — Adverse event report