Effects of mianserin in neuroleptic-induced parkinsonism.

It has been proposed that serotonin (5-HT) antagonists counteract neuroleptic-induced extrapyramidal symptoms by disinhibition of dopamine activity. The effects of the 5-HT antagonist mianserin, the anticholinergic drug procyclidine and placebo were evaluated in 16 psychiatric patients with chronic neuroleptic-induced parkinsonism in a double-blind cross-over trial. The patients received each drug in random order in 3-week periods separated by washout periods of 2 weeks. The effect of mianserin did not significantly differ from that of placebo, while parkinsonian symptoms were significantly reduced during treatment with procyclidine (P less than 0.05). Although mianserin was ineffective in chronic neuroleptic-induced parkinsonism, it cannot be excluded that 5-HT antagonists may be effective in the treatment of acute extrapyramidal side effects.