Drug interactions
Conivaptan + Tolterodine
Severity: Moderate
Conivaptan and Tolterodine: moderate 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
Conivaptan is a potent CYP3A4 inhibitor and may raise tolterodine exposure, which matters most in CYP2D6 poor metabolizers or when CYP2D6 is also inhibited. Higher levels may increase anticholinergic effects and QT prolongation.
What this interaction means in plain words
Conivaptan and Tolterodine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken.
Why it happens
Inhibition of CYP3A4-mediated metabolism of tolterodine.
What to do
Reduce tolterodine to 1 mg twice daily during co-administration, per labeling for CYP3A4 inhibitors. Monitor for anticholinergic effects and QT-related symptoms.
What to ask your pharmacist
- Should I take them at different times of day?
- Does the dose of either medicine need to change?
- Is there anything I should avoid, such as alcohol or certain foods, while on both?
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Other interactions of Tolterodine
Frequently asked questions
Can I take Conivaptan with Tolterodine?
MediHelp rates the interaction as moderate. Conivaptan and Tolterodine can affect each other. The combination is often manageable, but it may need a change of dose, a change of timing, or extra checks while both are taken. Conivaptan is a potent CYP3A4 inhibitor and may raise tolterodine exposure, which matters most in CYP2D6 poor metabolizers or when CYP2D6 is also inhibited. Higher levels may increase anticholinergic effects and QT prolongation.
How serious is the interaction between Conivaptan and Tolterodine?
MediHelp rates it moderate, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Reduce tolterodine to 1 mg twice daily during co-administration, per labeling for CYP3A4 inhibitors. Monitor for anticholinergic effects and QT-related symptoms.
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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