Major
Captopril × Spironolactone
ACE inhibitor×Potassium-sparing diuretics (mineralocorticoid receptor antagonists)
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.
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