lisinopril and potassium chloride

Pharmacodynamic interaction: lisinopril inhibits ACE, reducing aldosterone secretion. Aldosterone normally promotes renal potassium excretion, so its suppression decreases potassium loss. Concurrent administration of potassium chloride directly increases extracellular potassium, and the impaired renal excretion leads to additive hyperkalaemia.

Serum potassium may rise to dangerous levels, potentially causing life-threatening cardiac arrhythmias, including bradycardia, heart block, and ventricular fibrillation. Patients with renal impairment, diabetes, or those taking other potassium-sparing agents are at particularly high risk.

Avoid routine co-prescription unless there is documented hypokalaemia and the patient is closely monitored. If combined, measure serum potassium before initiation, within 1 week, and regularly thereafter. Adjust or stop potassium supplementation as needed. Monitor renal function and for signs of hyperkalaemia. Consider alternatives to potassium supplementation, such as dietary changes or potassium-sparing diuretics, with caution.

Well-established interaction, supported by pharmacological principles and extensive clinical experience. Product labels and clinical guidelines advise caution and monitoring when ACE inhibitors are used with potassium supplements. Multiple case reports document hyperkalaemia with this combination.