Drug interactions
Chlorpromazine + Perphenazine
Severity: Major
Chlorpromazine and Perphenazine: major interaction.
Last updated Sources: US FDA label
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 phenothiazines can prolong the QT interval, so combined use adds to arrhythmia risk. Additive sedation, anticholinergic effects, hypotension and extrapyramidal symptoms are also likely.
What this interaction means in plain words
Chlorpromazine 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.
Chlorpromazine belongs to Central Nervous System; Perphenazine belongs to Central Nervous System.
Why it happens
Additive cardiac potassium channel blockade and D2 antagonism; chlorpromazine may inhibit CYP2D6, raising perphenazine levels.
What to do
Avoid using two phenothiazines together and consolidate to one agent. If both continue, monitor ECG and electrolytes and watch for extrapyramidal effects.
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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References
Other interactions of Chlorpromazine
- Chlorpromazine + Dofetilide Contraindicated
- Chlorpromazine + Dronedarone Contraindicated
- Chlorpromazine + Droperidol Contraindicated
- Chlorpromazine + Ibutilide Contraindicated
- Chlorpromazine + Metrizamide Contraindicated
- Chlorpromazine + Panobinostat 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 Chlorpromazine with Perphenazine?
MediHelp rates the interaction as major. Chlorpromazine 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 phenothiazines can prolong the QT interval, so combined use adds to arrhythmia risk. Additive sedation, anticholinergic effects, hypotension and extrapyramidal symptoms are also likely.
How serious is the interaction between Chlorpromazine 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 using two phenothiazines together and consolidate to one agent. If both continue, monitor ECG and electrolytes and watch for extrapyramidal effects.
What other medicines interact with Chlorpromazine?
MediHelp also lists interactions of Chlorpromazine with, for example, Dofetilide, Dronedarone, Droperidol. The full list is on the Chlorpromazine page.
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