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.