Drug-induced Parkinsonism Associated with Amlodipine and Atenolol: A Case Report

Abstract

Background: Drug-induced parkinsonism (DIP) is a potentially reversible form of secondary parkinsonism associated with medicines that affect dopaminergic pathways. Although antipsychotic agents are the most frequently recognised causes, other drug classes may occasionally be implicated. This report describes an older patient who developed parkinsonian manifestations during long-term treatment with amlodipine and atenolol. Case presentation: A 79-year-old woman with type 2 diabetes mellitus and hypertension was admitted with cough and breathlessness. During hospitalisation, facial tremors, head-nodding movements, and cogwheel rigidity were observed. She had received amlodipine 5 mg and atenolol 100 mg once daily for two years and had no previous neurological illness or family history of Parkinson’s disease. On the basis of the clinical findings and medication history, DIP was suspected. Both antihypertensive agents were withdrawn, and symptomatic treatment with carbidopa/levodopa and trihexyphenidyl hydrochloride was initiated. Her tremors and rigidity gradually improved, and the parkinsonian symptoms had completely resolved at the one-month follow-up without recurrence. The WHO-UMC causality assessment classified the reaction as probable/likely. Conclusion: The temporal relationship and positive dechallenge support a medication-associated event, although simultaneous withdrawal prevented identification of the individual culprit. This case emphasises careful medication review, cautious causal assessment, and pharmacovigilance when new extrapyramidal symptoms occur during long-term therapy.