Less weight gain
Results of the 12-week study showed a significant difference in percent change in body weight from baseline between the two treatment groups, with a gain of 4.91% for the olanzapine plus samidorphan group vs. 6.77% for the olanzapine-alone group (between-group difference, 1.87%; P = .012).
Dr. Kahn noted this equates to an average weight gain of 2.8 kg (6.2 pounds) with olanzapine plus samidorphan and a gain of about 5 kg (11pounds) with olanzapine.
“It’s not a huge difference, but it’s certainly a significant one,” he said. “I also think it’s clinically important and significant.”
The reduction in weight gain compared with olanzapine was even maintained in patients assigned to olanzapine plus samidorphan who dropped out and did not complete the study, Dr. Kahn reported. “No one really had a weight gain,” he said.
In contrast, patients in the olanzapine groups who dropped out of the study had weight gain larger than their counterparts who stayed in it.
Further analysis showed the proportion of patients who gained 10% or more of their body weight by week 12 was 21.9% for those receiving olanzapine plus samidorphan vs. 30.4% for those receiving just olanzapine (odds ratio, 0.64; P = .075).
As expected, the improvement in Clinical Global Impression–Severity scale scores was almost identical between the olanzapine + samidorphan and olanzapine-only groups.
For safety, Dr. Kahn said the adverse event rates were “very, very similar” between the two treatment arms, which was a pattern that was repeated for serious AEs. This led him to note that “nothing out of the ordinary” was observed.
Clinical impact 'questionable'
Commenting on the study, Laura LaChance, MD, a psychiatrist at St. Mary’s Hospital Centre, McGill University, Montreal, said the actual amount of weight loss shown in the study “is of questionable clinical significance.”
Dr. Laura LaChance
On the other hand, Dr. LaChance said she has achieved “better results with metformin, which has a great safety profile and is cheap and widely available.
“Cost is always a concern in patients with psychotic disorders,” she concluded.
The study was funded by Alkermes. Dr. Kahn reported having relationships with Alkermes, Angelini, Janssen, Sunovion, Otsuka, Merck, Minerva Neuroscience, Roche, and Teva. Dr. Graham is an employee of Alkermes.
A version of this article first appeared on Medscape.com.