Severe hyperkalaemia due to a potential drug–drug interaction between eplerenone and antiretrovirals in a HIV-positive patient after a myocardial infarction

We present a case of a 48-year-old white HIV-1 positive man who presented an acute myocardial infarction. The patient was on ART for the last ten years with emtricitabine/tenofovir and ritonavir-boosted fosamprenavir. Eplerenone 25 mg/day was also initiated due to a left ventricular dysfunction. A week after discharge a routine laboratory examination revealed severe hyperkalaemia. Due to suspicion of a potential drug–drug interaction, both eplerenone and ARVs were interrupted. Despite daily treatment for hyperkalaemia, serum potassium levels normalized after two weeks. Eplerenone is metabolized by the hepatic P450 cytochrome isoenzyme CYP3A4; therefore, concomitant administration with CYP3A4 inhibitors, like ritonavir, may increase plasma levels of eplerenone and, therefore, the risk of side effects, mainly hyperkalaemia. Based on this case, it is important to alert the medical community of this possible life-threatening drug-drug interaction between eplerenone and ritonavir-boosted protease inhibitor.