Drug interactions
Anticholinergic / sedative combos + Clozapine
Severity: Major
Anticholinergic / sedative combos and Clozapine: major interaction.
Last updated Sources: UK SmPC
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
Clozapine is strongly anticholinergic, and combining it with other anticholinergic or sedative products may cause severe constipation, ileus, urinary retention, delirium and excess sedation. Clozapine gastrointestinal hypomotility can progress to serious bowel complications.
What this interaction means in plain words
Anticholinergic / sedative combos and Clozapine 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.
Why it happens
Additive antimuscarinic and CNS depressant effects causing reduced gastrointestinal motility.
What to do
Avoid unnecessary additional anticholinergic or sedative agents and review the total anticholinergic burden. Monitor bowel function, urinary symptoms and sedation, and treat constipation promptly.
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
- Clozapine Viatris 100 mg Orodispersible Tablets - SmPC sections 4.3/4.5 (class statement: substances possessing anticholinergic, hypotensive, or respiratory depressant effects; "Because of the possibility of additive effects, caution is essential in the concomitant administration of substances poss… — electronic medicines compendium (UK SmPC)
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 Anticholinergic / sedative combos with Clozapine?
MediHelp rates the interaction as major. Anticholinergic / sedative combos and Clozapine 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 is strongly anticholinergic, and combining it with other anticholinergic or sedative products may cause severe constipation, ileus, urinary retention, delirium and excess sedation. Clozapine gastrointestinal hypomotility can progress to serious bowel complications.
How serious is the interaction between Anticholinergic / sedative combos and Clozapine?
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 unnecessary additional anticholinergic or sedative agents and review the total anticholinergic burden. Monitor bowel function, urinary symptoms and sedation, and treat constipation promptly.
What other medicines interact with Clozapine?
MediHelp also lists interactions of Clozapine with, for example, Deferiprone, Irinotecan, Pimozide. The full list is on the Clozapine page.
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