Functional improvement of tacrolimus-induced parkinsonism with amantadine after liver transplantation: A case report

Drug-induced parkinsonism is the most common type of drug-induced movement disorder, whose symptoms can decrease patient quality of life and reduce medication compliance. Tacrolimus is a routinely used immunosuppressant agent after liver transplantation, with a well-known neurotoxic profile. There have been rare reports of tacrolimus-induced parkinsonism, but its pharmacologic management and functional impact remain poorly characterized in the literature. We present a case of tacrolimus-induced parkinsonism in a 62-year-old man after a liver transplant, resulting in significant neurologic impairments and multiple barriers to hospital discharge. His tremor, rigidity, bradykinesia, gait dysfunction, dysphonia, and dysphagia significantly improved after starting low-dose amantadine, with increased functional independence that allowed for a safe discharge. This is the first case in the literature detailing tacrolimus-induced parkinsonism's functional impairments improving with amantadine monotherapy.