Baclofen-induced myoclonus in patients with renal impairment: A case series

Baclofen is a derivative of gamma amino butyric acid and is used for control of pain and muscular spasms. It is primarily excreted via the kidneys. In patients with impaired renal functions, the half-life of baclofen is prolonged and symptoms of toxicity can occur with normal doses. Commonly reported symptoms of baclofen toxicity are somnolence, altered mentation, seizures and respiratory depression. Myoclonus secondary to baclofen toxicity is scarcely reported. This case series describes two patients with chronic kidney disease (CKD) who were prescribed regular doses of baclofen for analgesia, and subsequently developed generalized myoclonus. The symptoms resolved with omission of baclofen and haemodialysis. There is currently no consensus on dose modification of baclofen in renal impairment for prevention of adverse neurological events. However, considering the surmounting evidence for low threshold of baclofen toxicity in CKD, dose adjustment protocols or consensus on contraindication need to be established.