Drug interactions
Captopril-hydrochlorothiazide + Quinidine
Severity: Major
Captopril-hydrochlorothiazide and Quinidine: 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
Quinidine is a cation that may compete with other drugs for renal tubular secretion, but no clinically important change in hydrochlorothiazide exposure is established. The more relevant concern is that thiazide-induced hypokalemia and hypomagnesemia increase the risk of QT prolongation and torsades with quinidine.
What this interaction means in plain words
Captopril-hydrochlorothiazide and Quinidine 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.
Captopril-hydrochlorothiazide belongs to Cardiovascular; Quinidine belongs to Anti Parasitic.
Why it happens
Thiazide-induced hypokalemia and hypomagnesemia potentiate quinidine QT prolongation, with minor renal tubular competition.
What to do
Monitor serum potassium and magnesium and correct deficits, and obtain an ECG to monitor the QT interval. Consider the potassium effect of captopril when interpreting levels.
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 Captopril-hydrochlorothiazide
- Aliskiren + Captopril-hydrochlorothiazide Contraindicated
- Captopril-hydrochlorothiazide + Dofetilide Contraindicated
- Captopril-hydrochlorothiazide + Sacubitril / valsartan Contraindicated
- Aceclofenac + Captopril-hydrochlorothiazide Major
- Aldesleukin + Captopril-hydrochlorothiazide Major
- Amifostine + Captopril-hydrochlorothiazide Major
Other interactions of Quinidine
- Adagrasib + Quinidine Contraindicated
- Arsenic trioxide + Quinidine Contraindicated
- Artemether / lumefantrine + Quinidine Contraindicated
- Chloroquine + Quinidine Contraindicated
- Dofetilide + Quinidine Contraindicated
- Dronedarone + Quinidine Contraindicated
Frequently asked questions
Can I take Captopril-hydrochlorothiazide with Quinidine?
MediHelp rates the interaction as major. Captopril-hydrochlorothiazide and Quinidine 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. Quinidine is a cation that may compete with other drugs for renal tubular secretion, but no clinically important change in hydrochlorothiazide exposure is established. The more relevant concern is that thiazide-induced hypokalemia and hypomagnesemia increase the risk of QT prolongation and torsades with quinidine.
How serious is the interaction between Captopril-hydrochlorothiazide and Quinidine?
MediHelp rates it major, on a four-level scale (minor, moderate, major, contraindicated) based on published labels and references. What to do, in brief: Monitor serum potassium and magnesium and correct deficits, and obtain an ECG to monitor the QT interval. Consider the potassium effect of captopril when interpreting levels.
What other medicines interact with Captopril-hydrochlorothiazide?
MediHelp also lists interactions of Captopril-hydrochlorothiazide with, for example, Aliskiren, Dofetilide, Sacubitril / valsartan. The full list is on the Captopril-hydrochlorothiazide page.
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