Ca. Tamminga et al., CLOZAPINE IN TARDIVE-DYSKINESIA - OBSERVATIONS FROM HUMAN AND ANIMAL-MODEL STUDIES, The Journal of clinical psychiatry, 55(9), 1994, pp. 102-106
Clozapine has long been considered a useful treatment in patients who
have schizophrenia with the neuroleptic-induced delayed-onset side eff
ect tardive dyskinesia. We present data in support of that clinical im
pression using both an animal model of the disorder and dyskinetic pat
ients themselves. Clozapine produces a lower rate of oral dyskinesia i
n laboratory rats after 6 months of chronic treatment than does halope
ridol (8.6 +/- 1.3 vs. 13.6 +/- 1.4 vacuous chewing movements every 5
minutes, respectively), suggesting a lower propensity to cause tardive
dyskinesia. In the human, when clozapine was compared with haloperido
l in the treatment of patients with tardive dyskinesia, clozapine prod
uced significantly greater benefit for motor symptoms after 12 months
of treatment than did haloperidol (p < .001). Moreover, the dyskinesia
rebound, which occurred equally in both drug groups at the beginning
of the study, was sustained in the haloperidol group but lost in the c
lozapine-treated patients. These data suggest that dyskinetic patients
lose their symptoms of tardive dyskinesia, along with dopaminergic hy
persensitivity, with long-term clozapine treatment.