Reversal of orphenadrine-induced ventricular tachycardia with physostigmine.

A 3-year-old boy developed confusion, generalized tonic-clonic seizures, and sustained ventricular tachycardia following ingestion of an unknown quantity of orphenadrine (Norflex). Although refractory to precordial thump, synchronous cardioversion, and lidocaine, the ventricular tachycardia was reversed by intravenous administration of the tertiary acetylcholinesterase inhibitor physostigmine. We discuss the underlying physiology and manifestations of anticholinergic overdose, the specific manifestations of orphenadrine overdose, and the current recommendations regarding the utilization and toxicity of physostigmine in the treatment of anticholinergic syndromes and orphenadrine intoxication.