Dual therapy of olanzapine and samidorphan was found to be well tolerated among patients with schizophrenia. These findings, from an open-label, 52-week extension of the ENLIGHTEN-2 study, were presented at Psych Congress 2020 Virtual Experience, held online from September 11 to 13, 2020.

Outpatients (N=265) with a Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) diagnosis of schizophrenia who completed a randomized, double-blind, phase 3 clinical trial were eligible to enroll in this extension study (ENLIGHTEN-2-EXT, ClinicalTrials.gov Identifier: NCT2873208) within 7 days of study completion. Doses of olanzapine and samidorphan were based on the patient’s assigned group from the previous study (olanzapine 10, 15, or 20 mg with samidorphan 10 mg). Weight, waist circumference, and metabolic parameters were assessed in all patients, and they were also evaluated using the Positive and Negative Syndrome Scale (PANSS) and the Clinical Global Impression-Severity scale (CGI-S).

The mean age of participants was 40.7 years (standard deviation [SD], 9.7); 72.5% were men, mean body mass index was 26.8 kg/m2 (SD, 3.8), and mean PANSS score was 59.0 (SD, 11.8).

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At 52 weeks, the average change in absolute weight was -0.03 kg (SD, 6.22), which is equivalent to a proportional change of -0.05% (SD, 7.37%). Average waist size decreased by an average of 0.35 cm (SD, 6.1) from an average of 93.6 cm (SD, 11.0) at baseline.

Throughout the study duration, glycated hemoglobin and fasting levels of cholesterol, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglycerides, glucose, and insulin were consistently maintained as observed at baseline.

At the conclusion of the extension, patients had an average decrease in PANSS score of -0.2 (SD, 8.65). Throughout the study, at least 74% of participants maintained a CGI-S score £3.

The most common adverse events reported were weight loss (8.7%), headache (6.8%), and weight gain (6.0%). Serious adverse events (n=7) were observed among 5 participants and included 2 episodes of schizophrenic behavior and 1 instance each of acute kidney injury, agitation, alcoholic gastritis, psychotic disorder, and pulmonary embolism.

This study was limited by the possibility that the patients who discontinued treatment before 52 weeks may have experienced an adverse event that was not accounted for. The authors also cautioned that the study participants had moderate schizophrenic symptoms, and therefore these results may not be generalizable for patients experiencing severe schizophrenic symptoms.

These data support the long-term use of olanzapine and samidorphan as dual therapy for patients with mild schizophrenia. During this long-term extension study, participants were able to maintain their weight and metabolic levels. Adverse events were rare, and no new complications were identified during this trial.

Disclosure: A number of study authors reported being employed by Alkermes, which funded this study. Please refer to the original abstract for a full list of disclosures.


Kahn R, Silverman B, DiPetrillo L, et al. Phase 3 safety and tolerability results of the combination olanzapine and samidorphan in patients with schizophrenia: the 1-year ENLIGHTEN-2-Extension. Presented at: Psych Congress 2020 Virtual Experience; September 10-13, 2020. Poster 185.

This article originally appeared on Psychiatry Advisor