MajorACE inhibitor×Potassium-sparing diuretics (mineralocorticoid receptor antagonists)
Updated · Methodology
Mechanism
Captopril (ACE-I) reduces aldosterone synthesis, while spironolactone directly blocks aldosterone receptors. Both retain potassium. In chronic kidney disease and older patients, severe hyperkalaemia risk reaches 10–15% in the first weeks.
Symptoms
Muscle weakness, paraesthesia in the limbs, slowed pulse, arrhythmias. ECG shows peaked T waves and widened QRS. Severe cases progress to cardiac arrest. Symptoms typically appear within 1–2 weeks of starting the combination.
Management
The combination is appropriate in heart failure. Check potassium and creatinine 1 week after start, then monthly. If potassium exceeds 5.5 mmol/L, reduce the spironolactone dose; above 6.0 mmol/L, stop one of the drugs.
Check the full regimen, not just this pair
Opens the checker with these two drugs prefilled. Add the rest of the regimen and recompute additive risks.
Summary of a multi-drug list →
Medicine list: everything you take in one place →
Sources
- ESC: ESC Guidelines for the diagnosis and treatment of acute and chronic heart failure (2021)– McDonagh TA et al. Eur Heart J 2021;42:3599-3726
- AEMPS: Ficha técnica Captopril Cinfa 50 mg comprimidos EFG (2026)– AEMPS, CIMA, nº registro 62305, revisión 03/2026, secciones 4.4 y 4.5
- AEMPS: Ficha técnica Aldactone 25 mg comprimidos recubiertos con película (espironolactona) (2025)– AEMPS, CIMA, nº registro 39059, revisión 11/2025, secciones 4.4 y 4.5
- FDA: Aldactone (spironolactone) tablets – Prescribing Information (2025)– FDA, DailyMed SPL, Pfizer, разделы 5.1 и 7.1
- FDA: Captopril Tablets USP – Prescribing Information (2026)– FDA, DailyMed SPL, Bryant Ranch Prepack, Precautions (Drug Interactions)