Drug interactions
Pimozide + Tolterodine
Severity: Major
Pimozide and Tolterodine: major interaction.
Last updated Sources: Health Canada product monograph
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
Both drugs can prolong the QT interval, and tolterodine adds anticholinergic burden to pimozide. Pimozide is a sensitive QT-prolonging drug, so the combination increases the risk of torsades de pointes.
What this interaction means in plain words
Pimozide and Tolterodine 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.
Pimozide belongs to Central Nervous System; Tolterodine belongs to Genitourinary.
Why it happens
Additive QT prolongation, plus additive antimuscarinic effects.
What to do
Avoid the combination where possible and choose a bladder agent with less QT effect. If it is used, obtain an ECG and keep electrolytes normal.
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 Tolterodine
Other interactions of Pimozide
- Adagrasib + Pimozide Contraindicated
- Amiodarone + Pimozide Contraindicated
- Amisulpride + Pimozide Contraindicated
- Amitriptyline + Pimozide Contraindicated
- Amoxapine + Pimozide Contraindicated
- Anagrelide + Pimozide Contraindicated
Frequently asked questions
Can I take Pimozide with Tolterodine?
MediHelp rates the interaction as major. Pimozide and Tolterodine 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. Both drugs can prolong the QT interval, and tolterodine adds anticholinergic burden to pimozide. Pimozide is a sensitive QT-prolonging drug, so the combination increases the risk of torsades de pointes.
How serious is the interaction between Pimozide and Tolterodine?
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 the combination where possible and choose a bladder agent with less QT effect. If it is used, obtain an ECG and keep electrolytes normal.
What other medicines interact with Tolterodine?
MediHelp also lists interactions of Tolterodine with, for example, Clarithromycin, Clozapine, Cobicistat. The full list is on the Tolterodine page.
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