Combined use of an ACE-inhibitor and spironolactone in patients with heart insufficiency

A patient with cardiac insufficiency takes the ACE-Inhibitor Enalapril as well as Spironolactone regularly. In the interaction monographs of the German ABDA-database there is a note that combined use of these substances should be avoided due to an increased risk of hyperkalemia – is there a medication related problem? There is evidence from clinical studies, that combined use of ACE-inhibitors and potassium-sparing agents indeed increases the risk of severe hyperkalemia. The risk seems to be related to the dose of the potassium-sparing agent. However, in patients with cardiac insufficiency NYHA-class II-IV and an ejection fraction of ≤ 35%, the addition of spironolactone to an ACE-inhibitor and betablocking agent reduces mortality and hospitalization for cardiovascular problems. Therefore the combination is indicated in these patients. To minimize the risk for severe adverse events close monitoring of serum potassium and renal function is mandatory. Moreover, additional risk factors for hyperkalemia such as intake of potassium supplements or NSAID should be avoided.