Both drugs are mineralocorticoid receptor antagonists. Concurrent use produces dual aldosterone blockade; renal potassium excretion stops. Severe hyperkalaemia (K+ above 6.5 mmol/L) develops with risk of fatal arrhythmia.
Symptoms
Muscle weakness, paresthesia, bradycardia. ECG shows peaked T waves, QRS widening; in severe cases asystole.
Management
Combination contraindicated. For resistant heart failure choose one: spironolactone if renal function is preserved, or eplerenone if gynaecomastia developed on spironolactone. Check potassium at weeks 1, 2 and 4, then monthly.
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.