Amantadine versus trihexyphenidyl in the treatment of neuroleptic-induced parkinsonism.

Amantadine is a putative dopaminergic compound known to be therapeutically effective in idiopathic and postencephalitic Parkinson's disease. In a double-blind placebo-controlled crossover study of 39 psychiatric inpatients, amantadine and trihexyphenidyl were equally effective in treating drug-induced parkinsonism, and amantadine produced fewer and less severe side effects. The authors suggest that amantadine is an effective alternative to atropine-like agents, with fewer implications for long-term risk of tardive dyskinesia.