Clozapine + fluvoxamine — CYP1A2
- Clozapine is mainly CYP1A2-cleared
- Fluvoxamine strongly inhibits CYP1A2
- clozapine level often ↑ ~2–3×
- larger increases can occur
- Label: reduce clozapine to ~⅓ if combined
- Use TDM; watch sedation, seizure, ileus
Interaction at a glance
- Fluvoxamine strongly inhibits CYP1A2
- clozapine level often ↑ ~2–3×
- larger increases can occur
- Label: reduce clozapine to ~⅓ if combined
Mechanism
- Clozapine is mainly CYP1A2-cleared
Magnitude / time course
- Fluvoxamine strongly inhibits CYP1A2
- clozapine level often ↑ ~2–3×
- larger increases can occur
Clinical consequence
- Use TDM; watch sedation, seizure, ileus
Management
- Label: reduce clozapine to ~⅓ if combined
Self-check
- About how much can fluvoxamine raise clozapine levels?
Often ~2–3×; larger increases can occur.
- To about what fraction should clozapine be reduced when fluvoxamine is combined, per labeling?
About one-third.
- What should be monitored when fluvoxamine is added to clozapine?
Clozapine level + toxicity.
Drugs in this interaction (2)
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