In the study, asenapine 5mg twice daily was significantly more effective than placebo in improving both positive and negative symptoms associated with schizophrenia, based on the positive and negative syndrome scale (PANSS). This difference was seen starting at the second week of treatment. Positive symptoms include hallucinations and delusions; negative symptoms include lack of emotional expression.
In the study, 174 patients with schizophrenia were randomized to asenapine 5mg twice daily, risperidone 3mg twice daily, or placebo for six weeks. Asenapine was more effective than placebo in reducing total PANSS score as well as positive symptoms and negative symptoms when measured alone. Risperidone was more effective than placebo in reducing positive symptoms.
The majority of patients (83% asenapine, 79% placebo, 90% risperidone) experienced at least one adverse event (AEs) during the study. AEs were generally mild to moderate in severity. There was no difference between the treatment groups on the incidence of extrapyramidal symptoms.
Prolactin levels were higher in the risperidone group (79%) than in the asenapine or placebo groups (9% and 2%, respectively). Asenapine-treated patients reported a lower rate of clinically significant weight gain versus risperidone-treated patients (4.3% versus 17%, 1.9% for placebo).
“Currently available atypical antipsychotic drugs like risperidone are effective at reducing hallucinations and other positive symptoms associated with schizophrenia” said Steven Potkin, Department of Psychiatry and Human Behavior, University of California, Irvine. “Asenapine’s effect on negative symptoms, as seen in our trial, is an interesting finding.”