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NEW YORK — ALKS 3831, a treatment for schizophrenia composed of a flexible dose of olanzapine and a fixed dose of 10 mg samidorphan, demonstrated greater antipsychotic efficacy compared with placebo and a safety profile similar to that of olanzapine. The results of the phase 3 study (ClinicalTrials.gov identifier: NCT02634346) were presented at the American Psychiatric Association (APA) 2018 annual meeting, held May 5 to 9, 2018, in New York City.
Researchers conducted the 4-week, randomized, double-blind, placebo-controlled study to assess the antipsychotic efficacy and safety of ALKS 3831 in patients with acute exacerbations of schizophrenia. A total of 401 participants were randomly assigned to receive ALKS 3831, olanzapine, or placebo; patients who received olanzapine 6 months before screening were excluded from the study. Participants were treated in an inpatient setting for the first 2 weeks of the study and could be treated as in- or outpatients for the remaining 2 weeks.
The investigators assessed antipsychotic efficacy using the Positive and Negative Syndrome Scale (PANSS), Clinical Global Impression-Severity (CGI-S), and CGI-Improvement (CGI-I) scales. The safety profile was evaluated as adverse events.
Results showed that 91%, 89%, and 83% of participants receiving ALKS 3831, olanzapine, and placebo, respectively, completed treatment. The most common reason for treatment discontinuation was withdrawal by patient (6% in the ALKS 3831 and placebo groups, and 7% in the olanzapine group). Baseline mean scores were 101.7 for PANSS total score and 5.1 for CGI-S score. The mean olanzapine dose was 18.4 mg/day in both active treatment groups.
Compared with placebo, least squares mean difference from baseline to 4 weeks in PANSS total score was −6.4 (P <.001) for the ALKS 3831 group and −5.3 (P =.004) for the olanzapine group. When researchers examined the CGI-S scores, least squares mean difference from baseline to 4 weeks was −0.38 (P =.002) for the ALKS 3831 group vs placebo and −0.44 (P <.001) for the olanzapine group vs placebo.
The proportion of patients with an improvement in PANSS response (≥30% improvement from baseline) at 4 weeks was 60%, 54%, and 38% in the ALKS 3831, olanzapine, and placebo groups, respectively. In addition, 58%, 51%, and 33% of participants in the ALKS 3831, olanzapine, and placebo groups, respectively, showed improvements in CGI-I response (score ≤2) at 4 weeks.
The investigators note that discontinuation resulting from adverse events was low in all groups. Common adverse events included weight gain, somnolence, dry mouth, anxiety, headache, schizophrenia, and agitation.
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Potkin SG, Silverman B, Simmons A, Jiang Y, DiPetrillo L, McDonnell D. A phase 3 study to determine the antipsychotic efficacy and safety of ALKS 3831 in adult patients with acute exacerbation of schizophrenia. Presented at: 2018 American Psychiatric Association (APA) Annual Meeting; New York, NY; May 5-9. Poster 169.