Liver, Renal, and Cardiovascular Failure After Unintentional Overdose of Tizanidine in a 2-Year-Old Child.

Tizanidine is a central alpha-2 adrenergic receptor agonist indicated for the treatment of spasticity in adults; however, its use in the pediatric population is considered off-label. In adults, the dose is gradually titrated until the desired reduction in muscle tone is achieved. Hypotension is a frequent adverse effect, but impaired liver function is not characteristic of alpha-2 adrenergic agonist overdose. We report a 2-year-old male affected with spastic quadriplegia (treated with clonazepam and tizanidine) and dysphagia (he was fed by nasogastric tube). Two days before admission caregivers ran out of clonazepam so they increased the tizanidine dose from 0.15 mg/kg/day to 1.6 mg/kg/day. Simultaneously his nasogastric tube fell out; therefore, he was unable to maintain proper oral nutrition and hydration. He presented to the emergency department hemodynamically unstable, with impaired consciousness and signs of severe dehydration. Blood tests revealed hepatic dysfunction without cholestasis and renal dysfunction. He was transferred to the pediatric intensive care unit. Treatment was mainly supportive, apart from tizanidine discontinuation. Metabolic and infectious diseases were ruled out so he was finally diagnosed as having liver, renal, and cardiovascular failure after tizanidine overdose, worsened by dehydration. His clinical status improved, and after 3 weeks he was discharged from the hospital, receiving clonidine instead of tizanidine to treat spasticity. Tizanidine overdose can result in serious complications that can be worsened because of patient comorbidities.