Effect of different neuroleptics in tardive dyskinesia and parkinsonism. A video-controlled multicenter study with chlorprothixene, perphenazine, haloperidol and haloperidol + biperiden. Nordic Dyskinesia Study Group.

Thirty-three chronic psychiatric patients with tardive dyskinesia (TD) were included in a video-controlled multicenter study of the effect of chlorprothixene, perphenazine, haloperidol and haloperidol + biperiden in TD and parkinsonism. The drugs were given in a cross-over design in randomized order in dosages equipotent to the earlier neuroleptic treatment and administered for periods of 6 months with 6-week placebo periods before and after. A total of 55 treatment periods were completed; only seven patients were able to go through all three treatment phases (= 96 weeks). Perphenazine (20.5 mg/day), haloperidol (5.5 mg/day), and haloperidol (11 mg/day) + biperiden (7 mg/day) induced a moderate suppression of TD and at the same time produced a corresponding aggravation in parkinsonism. Chlorprothixene (142 mg/day) had only a slight TD reducing effect and did not change parkinsonism. Thus the TD suppressing effect was inversely related to the parkinsonian-inducing effect of the neuroleptics. Following withdrawal of the drugs, TD increased in some cases and decreased in others compared to the pretreatment level. No significant correlation was found between the intensity of the withdrawal TD and either drugs or preceding parkinsonism or TD suppression. Only in a subgroup of seven patients who consecutively received all three neuroleptics, perphenazine, but not haloperidol and chlorprothixene, produced a post-treatment aggravation which was correlated to the parkinsonsim and TD suppression during treatment. Independent of the neuroleptic given, the TD intensity increased significantly from the first to the third placebo period. This suggests that drug holidays are inappropriate to prevent TD induction/aggravation.