Drug interactions
Clozapine + Lorazepam
Severity: Major
Clozapine and Lorazepam: major interaction.
Last updated Sources: US FDA label
For healthcare professionals — reference only. This page is a brief summary, not medical advice and not a substitute for official labeling or clinical judgement. Always verify before prescribing or dispensing.
Summary
Concurrent use of clozapine and a benzodiazepine has been associated with excessive sedation, marked hypotension, respiratory depression and rarely cardiorespiratory collapse. The risk is highest during clozapine initiation or dose escalation and with parenteral lorazepam.
What this interaction means in plain words
Clozapine and Lorazepam can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for.
Clozapine belongs to Central Nervous System; Lorazepam belongs to Central Nervous System.
Why it happens
Pharmacodynamic synergy of CNS and respiratory depression, with additive hypotension from clozapine's alpha-adrenergic blockade.
What to do
Avoid parenteral lorazepam during clozapine titration where possible. If both are needed, use low doses and monitor blood pressure, heart rate, respiration and sedation.
What to ask your pharmacist
- Does the benefit of taking both outweigh the risk in my case?
- Do I need any blood test, ECG or other check while on both?
- What early warning signs should I watch for, and what should I do if they appear?
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References
Other interactions of Lorazepam
Other interactions of Clozapine
- Clozapine + Deferiprone Contraindicated
- Clozapine + Irinotecan Contraindicated
- Clozapine + Pimozide Contraindicated
- Clozapine + Thioridazine Contraindicated
- Acalabrutinib + Clozapine Major
- Adagrasib + Clozapine Major
Frequently asked questions
Can I take Clozapine with Lorazepam?
MediHelp rates the interaction as major. Clozapine and Lorazepam can interact in a way that may be serious. Using them together is sometimes necessary, but it needs a deliberate decision by the prescriber, a plan for monitoring, and clear advice on the warning signs to watch for. Concurrent use of clozapine and a benzodiazepine has been associated with excessive sedation, marked hypotension, respiratory depression and rarely cardiorespiratory collapse. The risk is highest during clozapine initiation or dose escalation and with parenteral lorazepam.
How serious is the interaction between Clozapine and Lorazepam?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Avoid parenteral lorazepam during clozapine titration where possible. If both are needed, use low doses and monitor blood pressure, heart rate, respiration and sedation.
What other medicines interact with Lorazepam?
MediHelp also lists interactions of Lorazepam with, for example, Alfentanil, Alprazolam, Amobarbital. The full list is on the Lorazepam page.
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