Drug interactions
Ketoconazole + Protriptyline
Severity: Major
Ketoconazole and Protriptyline: 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
Both agents may prolong the QT interval, raising the risk of ventricular arrhythmias. Ketoconazole may also increase tricyclic levels via CYP inhibition.
What this interaction means in plain words
Ketoconazole and Protriptyline 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 QT prolongation, with possible CYP2D6/3A4 inhibition increasing protriptyline exposure.
What to do
Avoid the combination if possible; if used, check ECG and electrolytes and monitor for anticholinergic and cardiac toxicity.
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 Ketoconazole
- Alfuzosin + Ketoconazole Contraindicated
- Alprazolam + Ketoconazole Contraindicated
- Avanafil + Ketoconazole Contraindicated
- Conivaptan + Ketoconazole Contraindicated
- Dihydroergotamine intranasal + Ketoconazole Contraindicated
- Dihydroergotamine + Ketoconazole Contraindicated
Frequently asked questions
Can I take Ketoconazole with Protriptyline?
MediHelp rates the interaction as major. Ketoconazole and Protriptyline 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 agents may prolong the QT interval, raising the risk of ventricular arrhythmias. Ketoconazole may also increase tricyclic levels via CYP inhibition.
How serious is the interaction between Ketoconazole and Protriptyline?
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 if possible; if used, check ECG and electrolytes and monitor for anticholinergic and cardiac toxicity.
What other medicines interact with Ketoconazole?
MediHelp also lists interactions of Ketoconazole with, for example, Alfuzosin, Alprazolam, Avanafil. The full list is on the Ketoconazole page.
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