Article type: Case Report
Article title: Myoclonus secondary to amantadine: Case report and literature review
Journal: Clinics and Practice
Year: 2023
Authors: Jamir Pitton Rissardo, Ana LetÃcia Fornari Caprara
E-mail: jamirrissardo@gmail.com
ABSTRACT
The usual adverse events of amantadine are dizziness, dry mouth, and peripheral edema. Postmarketing experience has revealed abnormal movements such as tremors, involuntary muscle contractions, and gait abnormalities. Herein, we report a case of an elderly male who presented with generalized twitching associated with amantadine. A 64-year-old male presenting with jerking movements within one day of onset was admitted. Sudden and involuntary distal lower and upper limb muscle twitching was observed. The subject presented subsequent brief movements when attempting to stand or hold arms antigravity. He was diagnosed with Parkinson’s disease three years ago. Eight days before the presentation to the emergency department, he consulted with his primary care physician, who prescribed amantadine to improve his motor symptoms. On the seventh day, he developed brisk abnormal movements. Laboratory exams, neuroimaging, and electroencephalogram were unremarkable. Amantadine was discontinued. After three days, the patient reported that his jerking movements had fully recovered. To the authors’ knowledge, 22 individuals with amantadine-associated myoclonus had already been reported in the literature. The pathophysiology of amantadine-induced myoclonus is probably related to serotoninergic pathways. Myoclonus secondary to amantadine was slightly more common in men. The population affected was elderly, with a mean and median age of 67.7 and 64 years.
Keywords: Parkinson’s disease, myoclonus, movement disorder, amantadine, 1-adamantylamine
Full text available at:
DOI
10.3390/clinpract13040075
Citation
Rissardo JP, Fornari Caprara AL. Myoclonus Secondary to Amantadine: Case Report and Literature Review. Clin Pract 2023;13:830-837
Figure 1. Mechanism of action and skeletal formula of amantadine. DA, dopamine; NE, norepinephrine; NMDA, N-methyl-D-aspartate.
Figure 2. Plasma concentration of amantadine (ng/mL). Ineffective, effective, unknown, and toxic ranges.
Table 1. Clinical reports of myoclonus associated with amantadine.