Haloperidol decanoate as a replacement for maintenance therapy with intramuscular fluphenazine decanoate in schizophrenia and other chronic psychoses.

Thirty-five psychotic male inpatients receiving optimal neuroleptic maintenance therapy, with fluphenazine decanoate (once every 3-weeks), and one receiving chlorpromazine entered a 24-week study with haloperidol decanoate administered once every 4 weeks, at a dose based on mg equivalence between fluphenazine decanoate and haloperidol decanoate; as regards the latter, this dose was estimated to be comparable with 20 times a daily haloperidol dose. Psychotic symptom severity, evaluated at the end of each treatment period by 8 out of 9 assessed symptoms from the Brief Psychiatric Rating Scale, showed haloperidol decanoate to be of similar efficacy to previously used maintenance medication. The symptom emotional withdrawal was significantly improved by the end of the study. In addition, 18 patients out of 20 were successfully withdrawn from antiparkinsonian therapy without experiencing an enhancement of extrapyramidal side-effects.