Drug interactions
Ketoconazole + Perphenazine
Severity: Major
Ketoconazole and Perphenazine: 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 drugs can prolong the QT interval, and ketoconazole may reduce perphenazine metabolism. This raises the risk of arrhythmia and extrapyramidal or sedative effects.
What this interaction means in plain words
Ketoconazole and Perphenazine 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.
Ketoconazole belongs to Anti Fungals; Perphenazine belongs to Central Nervous System.
Why it happens
Additive QT prolongation with possible CYP inhibition by ketoconazole reducing perphenazine clearance.
What to do
Avoid if possible, or obtain a baseline and follow-up ECG, correct electrolytes and monitor for perphenazine toxicity. Consider a lower perphenazine dose.
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
Other interactions of Perphenazine
- Ibutilide + Perphenazine Contraindicated
- Perphenazine + Pimozide Contraindicated
- Perphenazine + Thioridazine Contraindicated
- Adagrasib + Perphenazine Major
- Alfentanil + Perphenazine Major
- Amiodarone + Perphenazine Major
Frequently asked questions
Can I take Ketoconazole with Perphenazine?
MediHelp rates the interaction as major. Ketoconazole and Perphenazine 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 ketoconazole may reduce perphenazine metabolism. This raises the risk of arrhythmia and extrapyramidal or sedative effects.
How serious is the interaction between Ketoconazole and Perphenazine?
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 if possible, or obtain a baseline and follow-up ECG, correct electrolytes and monitor for perphenazine toxicity. Consider a lower perphenazine dose.
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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