1. There was no statistically significant difference in the rate of relapse between patients treated with the long-acting injectable paliperidone versus long-acting injectable haloperidol for schizophrenia.
2. While paliperidone treatment resulted in greater overall weight gain and prolactinemia, haloperidol treatment resulted in weight loss and increased rates of akathisia.
Evidence Rating Level: 2 (Good)
Study Rundown: Schizophrenia and schizoaffective disorders demonstrate high relapse rates, often secondary to medication non-adherence. The long-acting injectable formulations of antipsychotics can be given at 2 to 4 week intervals instead of daily oral drugs, thereby reducing the risk of non-adherence. However, the merits of older first generation versus newer atypical antipsychotics remain debated. This study is the first randomized control trial to compare the injectable formulations of a first generation antipsychotic (haloperidol) with an atypical antipsychotic (paliperidone). No significant difference was noted between injectable forms of haloperidol and paliperidone in preventing relapse, although the two drugs differed in their adverse effect profile.
By demonstrating no difference in efficacy between first and second-generation antipsychotics, this study may allow for the selection of antipsychotics on the basis of associated adverse events. However, this study is not without limitations. In applying these findings to drug choice, other factors such as cost will need to be incorporated. Moreover, the wide confidence interval for the measured hazard ratio of the relative incidence of relapse using paliperidone versus haloperidol may obscure potentially clinically relevant differences between the two medications. Further studies are required to explore this possibility.
In-Depth [randomized controlled trial]: This study was conducted at 22 U.S. sites and enrolled 311 adults diagnosed with schizophrenia or schizoaffective disorder who were identified as being at risk of relapse based on prior history. Primary analysis included 147 participants randomized to either paliperidone or haloperidol therapy. The follow-up period varied from 12 to 24 months with a median of 488 days.
Relapse was defined by a number of outcomes including the need for hospitalization or an increased frequency of outpatient visits. There was no significant difference between paliperidone and haloperidol in terms of rates of relapse. 33.8% of patients in the paliperidone group and 32.4% of those in the haloperidol group relapsed, with a hazard ratio of 0.98 (95% CI, 0.65-1.47) for paliperidone versus haloperidol. At 12 months, the weight in the paliperidone group increased by 3.46 kg (least-squares mean, 95% CI, 1.83 – 5.09, p< 0.01) and decreased in the haloperidol group by 1.93 kg (least-squares mean, 95% CI, – 3.56 to – 0.31, p< 0.01). The haloperidol group showed significantly greater worsening of akathisia. Paliperidone caused a significantly greater rise in serum prolactin level in both men and women.
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