Long-Term Maintenance Therapy With Quetiapine Versus Haloperidol Decanoate in Patients With Schizophrenia or Schizoaffective Disorder

Objective: To compare the long-term efficacy and tolerability of oral quetiapine with those of intramuscular haloperidol.

Method: Patients with DSM-IV-diagnosed schizophrenia or schizoaffective disorder requiring long-term antipsychotic treatment were randomly assigned to open-label oral quetiapine or intramuscular haloperidol decanoate for 48 weeks. Clinicians were instructed to target dosing at 500 mg/day of quetiapine or 200 mg of haloperidol decanoate every 4 weeks. The Positive and Negative Syndrome Scale was used to assess efficacy; the Simpson-Angus Scale and the Barnes Akathisia Scale were used to assess safety and tolerability. For statistical analyses, a general linear mixed-model repeated-measures analysis of covariance was used, with change scores for dependent variables computed with the baseline score as covariate. Data were collected from 1998 to 2001.

Results: Thirty-five patients were enrolled, but 6 did not participate after being informed of their treatment assignment; 4 of the 6 withdrawals were assigned to haloperidol decanoate. Mean doses at week 48 were 493 mg/day of quetiapine (N = 16) and 170 mg/28 days of haloperidol decanoate (N = 9). Survival analysis showed no between-group differences in estimates of the number of patients remaining exacerbation-free over time. Both drugs were efficacious, but quetiapine was significantly better than haloperidol decanoate in controlling negative symptoms (p < .05). The incidence of extrapyramidal symptoms was low in both groups; patients receiving quetiapine showed significantly greater improvement in rigidity and akathisia (p < .05).

Conclusion: Oral quetiapine was as efficacious as intramuscular haloperidol in preventing symptom exacerbation over 48 weeks in patients with schizophrenia or schizoaffective disorder, with fewer extrapyramidal symptoms, especially rigidity and akathisia. Quetiapine was more efficacious than haloperidol decanoate in treating negative symptoms.