Drug interactions
Guanfacine + Verapamil
Severity: Moderate
Guanfacine and Verapamil: 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
Verapamil increases guanfacine concentrations through CYP3A4 inhibition. This can lead to excess hypotension, bradycardia and sedation, and the effects are additive pharmacodynamically.
What this interaction means in plain words
Guanfacine and Verapamil 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.
Guanfacine belongs to Cardiovascular; Verapamil belongs to Cardiovascular.
Why it happens
CYP3A4 inhibition reduces guanfacine metabolism, with additive hypotensive and bradycardic effects.
What to do
Reduce extended-release guanfacine to half the recommended dose with moderate CYP3A4 inhibitors, and monitor blood pressure and heart rate.
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 Verapamil
- Dofetilide + Verapamil Contraindicated
- Flibanserin + Verapamil Contraindicated
- Lomitapide + Verapamil Contraindicated
- Lonafarnib + Verapamil Contraindicated
- Pimozide + Verapamil Contraindicated
- Acebutolol + Verapamil Major
Other interactions of Guanfacine
- Clonidine + Guanfacine Major
- Guanfacine + Lofexidine Major
- Aldesleukin + Guanfacine Moderate
- Amiodarone + Guanfacine Moderate
- Amisulpride + Guanfacine Moderate
- Amitriptyline + Guanfacine Moderate
Frequently asked questions
Can I take Guanfacine with Verapamil?
MediHelp rates the interaction as moderate. Guanfacine and Verapamil 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. Verapamil increases guanfacine concentrations through CYP3A4 inhibition. This can lead to excess hypotension, bradycardia and sedation, and the effects are additive pharmacodynamically.
How serious is the interaction between Guanfacine and Verapamil?
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 extended-release guanfacine to half the recommended dose with moderate CYP3A4 inhibitors, and monitor blood pressure and heart rate.
What other medicines interact with Verapamil?
MediHelp also lists interactions of Verapamil with, for example, Dofetilide, Flibanserin, Lomitapide. The full list is on the Verapamil page.
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