Drug interactions
Cobicistat + Tolterodine
Severity: Major
Cobicistat and Tolterodine: major interaction.
Last updated
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
Cobicistat is a strong CYP3A inhibitor and raises tolterodine concentrations, especially in CYP2D6 poor metabolizers. This increases anticholinergic adverse effects and QT risk.
What this interaction means in plain words
Cobicistat 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.
Cobicistat belongs to Miscellaneous; Tolterodine belongs to Genitourinary.
Why it happens
Strong CYP3A4 inhibition by cobicistat (plus some CYP2D6 inhibition) reduces tolterodine metabolism.
What to do
Reduce the tolterodine dose to a maximum of 2 mg daily (1 mg twice daily for immediate-release) and monitor for anticholinergic effects and QT prolongation.
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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Other interactions of Tolterodine
Other interactions of Cobicistat
- Alfuzosin + Cobicistat Contraindicated
- Apalutamide + Cobicistat Contraindicated
- Cobicistat + Colchicine Contraindicated
- Cobicistat + Dronedarone Contraindicated
- Cobicistat + Eletriptan Contraindicated
- Cobicistat + Eplerenone Contraindicated
Frequently asked questions
Can I take Cobicistat with Tolterodine?
MediHelp rates the interaction as major. Cobicistat 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. Cobicistat is a strong CYP3A inhibitor and raises tolterodine concentrations, especially in CYP2D6 poor metabolizers. This increases anticholinergic adverse effects and QT risk.
How serious is the interaction between Cobicistat 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: Reduce the tolterodine dose to a maximum of 2 mg daily (1 mg twice daily for immediate-release) and monitor for anticholinergic effects and QT prolongation.
What other medicines interact with Tolterodine?
MediHelp also lists interactions of Tolterodine with, for example, Clarithromycin, Clozapine, Dronedarone. The full list is on the Tolterodine page.
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