Double-blind comparison of haloperidol decanoate and fluphenazine decanoate effectiveness, side-effects, dosage and serum levels during a six months' treatment for relapse prevention.

In this present study 31 schizophrenic patients were treated for six months for relapse prevention under double-blind conditions with either haloperidol decanoate (22) or fluphenazine decanoate (9). In respect of the prophylactic action, both depot neuroleptics proved to be equal during the comparatively short period of observation. In both groups a psychotic relapse occurred that could not be managed by increasing the depot dosage. No side-effects worth mentioning appeared in either group of patients; patients under haloperidol decanoate, however, only required half the quantity of anti-parkinson medication as compared with patients treated with fluphenazine decanoate, and also displayed extrapyramidal motor symptoms (EPMS) to a lesser degree. Patients received a mean monthly injection of 80 mg of Haloperidol, reaching steady-state serum levels of about 3 ng/ml in the third injection interval. Fluphenazine serum levels known so far for seven patients amount to 0.8 ng/ml after fluphenazine injections of 21 mg every 14 days.