Involuntary Muscular Movements as an Adverse Reaction to Sacubitril/Valsartan in a Patient With Cardiomyopathy and Multiple Comorbidities: A Case Report

Sacubitril/valsartan, an angiotensin receptor–neprilysin inhibitor used in heart failure with reduced ejection fraction, is known to cause hypotension, hyperkalaemia and renal impairment, whereas involuntary muscular movements are a rare neuromuscular reaction reported mainly through post-marketing surveillance. We describe a 43-year-old man with cardiomyopathy, heart failure with recovered ejection fraction, non-cirrhotic portal hypertension, biopsy-confirmed diabetic nephropathy, haemolytic anaemia and miliary tuberculosis who developed non-painful, sporadic involuntary jerks of the upper and lower limbs within 12–72 hours of starting sacubitril/valsartan 24/26 mg twice daily, the lowest recommended dose. Hyponatraemic, uraemic, hypoglycaemic, septic and hepatic encephalopathy and seizure disorder were considered and excluded on clinical and biochemical grounds. The drug was withdrawn, and the movements resolved completely within 24–48 hours without specific treatment; rechallenge was not attempted. Causality was assessed as probable by the World Health Organization–Uppsala Monitoring Centre criteria, with a Naranjo score of 5 and severity level 3 on the Hartwig–Siegel scale. This case extends the reported patient profile to a younger patient with recovered ejection fraction and severe multisystem disease, in whom combined hepatic and renal impairment may have raised exposure to the active metabolite LBQ657. Clinicians starting sacubitril/valsartan in patients with impaired organ clearance should remain alert to this reaction and report suspected cases to pharmacovigilance centres.