Amisulpride versus risperidone in the treatment of schizophrenic patients: a double-blind pilot study in Taiwan

The atypical antipsychotics, amisulpride and risperidone, have different receptor affinity characteristics. Although the relative efficacy of both drugs compared to conventional antipsychotics is well established, it remains unclear how the efficacy of amisulpride compares with risperidone. There have been no controlled studies comparing amisulpride to risperidone in Asian patients. The purpose of this study was to compare the efficacy and safety of amisulpride with that of risperidone in Taiwanese schizophrenic patients.

Patients with productive positive symptoms (n = 48) were enrolled into this double-blind, randomized pilot study for 6 weeks. Patients received either amisulpride (400-800 mg/day) or risperidone (4-8 mg/day). Positive and Negative Syndrome Scale (PANSS), Clinical Global Impression (CGI), Social and Occupational Functioning Assessment Scale (SOFAS), and patients' subjective responses to treatment were assessed during the trial period. Adverse events were recorded at each follow-up visit.

At the end of the trial, the mean dosage was 630 +/- 134 mg/day and 6.88 +/- 1.54 mg/day for amisulpride and risperidone, respectively. There was no significant difference in the reduction of the PANSS total score (amisulpride -24.1 versus risperidone -28.4, p = 0.999), the PANSS positive subscale score (amisulpride -6.8 versus risperidone -8.3, p = 0.467), the PANSS negative subscale score (amisulpride -5.6 versus risperidone -6.4, p = 0.999), or the CGI score between the two groups. The extrapyramidal symptom ratings, the improvement in the SOFAS (amisulpride 11.1 versus risperidone 10.0) and the subjective response (amisulpride 82% versus risperidone 83%) were comparable. No serious adverse events were recorded in either treatment group. There was a statistically significant body weight gain in the risperidone group. In contrast, there was a statistically, though not clinically, significant reduction of blood pressure and heart rate in the amisulpride group.

This study suggests that amisulpride is as effective as risperidone in the treatment of patients with schizophrenia. Both drugs were well tolerated, but had different side effect profiles.