clozapine
Antipsychotic • Brands: CLOZARIL
Last reviewed: 2025-12-28
General information
- Class: Antipsychotic
- Common US brands: CLOZARIL
- Therapeutic drug monitoring recommended; reference range 350–600 ng/mL.
- Last reviewed: 2025-12-28
Dosing & forms
- Forms/strengths: —
- Frequency: —
- Food: —
- Typical range: —
Mechanism (brief)
Mechanism not fully known. Proposed efficacy via antagonism at dopamine D2 and serotonin 5‑HT2A receptors; also antagonizes adrenergic, cholinergic, and histaminergic receptors.
Metabolism & Half‑life
- Metabolism: CYP1A2, CYP3A4, CYP2D6
- Half‑life: Single-dose mean 8 h; Single-dose range 4–12 h; Steady-state mean 12 h; Steady-state range 4–66 h
Therapeutic Drug Monitoring (TDM)
Recommended: Yes
Reference range: 350–600 ng/mL
Sampling: Trough at steady state: ~12 h post‑dose (or immediately before morning dose if BID).
Monitoring highlights
- —
Sources
- CLOZARIL (clozapine) label — DailyMed (2025)
- AGNP Consensus Guidelines for TDM in Psychiatry (update) — Pharmacopsychiatry (2018)
- Therapeutic Drug Monitoring in Psychiatry (Review) — Frontiers/PMC (2024)
- Clozapine TDM Guidance — TEWV NHS (2023)
- TDM standardized to 12‑h post‑dose — Acta Psychiatr Scand (2017)
- Smoking cessation and clozapine levels — PMC (2023)
- Clozaril label: inflammation may increase levels — DailyMed (2025)
- Clozaril label: fluvoxamine ~3x increase — DailyMed (2025)
- Fluvoxamine markedly increases clozapine levels — PubMed (1996)
- FDA removes Clozapine REMS — FDA (2025)
- Transdiagnostic effectiveness and safety of clozapine in individuals with psychotic, affective, and personality disorders: nationwide and meta-analytic comparisons with other antipsychotics — Lancet Psychiatry (2025)