Drug interactions
Quinapril + Thioridazine
Severity: Minor
Quinapril and Thioridazine: minor 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
Phenothiazines such as thioridazine can cause orthostatic hypotension through alpha-adrenergic blockade. Combined with an ACE inhibitor such as quinapril, blood pressure lowering may be greater than expected, particularly at treatment start or after dose increases.
What this interaction means in plain words
Quinapril and Thioridazine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised.
Why it happens
Additive hypotensive effects from alpha-1 blockade by thioridazine and ACE inhibition by quinapril.
What to do
Check blood pressure and orthostatic symptoms when either drug is started or the dose is changed. Counsel the patient to rise slowly.
What to ask your pharmacist
- Is there anything I should notice while taking both?
- Do I need to tell my doctor at the next visit?
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Other interactions of Thioridazine
- Abiraterone + Thioridazine Contraindicated
- Adagrasib + Thioridazine Contraindicated
- Amiodarone + Thioridazine Contraindicated
- Amisulpride + Thioridazine Contraindicated
- Amitriptyline + Thioridazine Contraindicated
- Amoxapine + Thioridazine Contraindicated
Frequently asked questions
Can I take Quinapril with Thioridazine?
MediHelp rates the interaction as minor. Quinapril and Thioridazine have a small, usually unimportant interaction. Most people can take both; the pharmacist may still mention it so that any unexpected effect is recognised. Phenothiazines such as thioridazine can cause orthostatic hypotension through alpha-adrenergic blockade. Combined with an ACE inhibitor such as quinapril, blood pressure lowering may be greater than expected, particularly at treatment start or after dose increases.
How serious is the interaction between Quinapril and Thioridazine?
MediHelp rates it minor, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Check blood pressure and orthostatic symptoms when either drug is started or the dose is changed. Counsel the patient to rise slowly.
What other medicines interact with Thioridazine?
MediHelp also lists interactions of Thioridazine with, for example, Abiraterone, Adagrasib, Amiodarone. The full list is on the Thioridazine page.
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