Pharmacokinetic interactions involving clozapine

Area of Science:

• Pharmacology
• Drug Metabolism
• Clinical Pharmacy

Background:

• Clozapine metabolism is intricate and not fully elucidated.
• Pharmacokinetic interactions with co-administered drugs are documented, but mechanisms are often unclear.

Purpose of the Study:

• To review human clozapine metabolism.
• To investigate suspected pharmacokinetic interactions involving clozapine.

Main Methods:

• A comprehensive review of published clinical trials and case reports.
• Focus on studies detailing clozapine metabolism and drug interactions.

Main Results:

• Hepatic cytochrome P450 1A2 (CYP1A2) significantly influences clozapine metabolism.
• CYP1A2 inducers (e.g., carbamazepine, tobacco smoke) may decrease clozapine levels.
• CYP1A2 inhibitors (e.g., caffeine, erythromycin) and CYP2D6 inhibitors may increase clozapine levels, with the latter's mechanism being unclear.

Conclusions:

• Avoid co-administration of clozapine with drugs known to alter its metabolism.
• Exercise caution with drugs affecting CYP1A2 and CYP2D6 due to potential interactions.
• Further research into clozapine pharmacokinetics is essential for ensuring its safe and effective use.