, new research suggests. However, at least one expert says the weight difference between the two drugs is of “questionable clinical benefit.”
Last year, the Food and Drug Administration approved the drug for the treatment of adults with schizophrenia or bipolar I disorder, as a maintenance monotherapy or as either monotherapy or an adjunct to lithium or valproate for acute manic or mixed episodes.
In the ENLIGHTEN-Early trial, researchers examined weight-gain profiles of more than 400 patients with early schizophrenia, schizophreniform disorder, or bipolar I disorder.
Results showed those given combination treatment gained just over half the amount of weight as those given monotherapy. They were also 36% less likely to gain at least 10% of their body weight during the 12-week treatment period.
Courtesy Mount Sinai Health System
Dr. René S. Kahn
They indicate that the weight-mitigating effects shown with olanzapine plus samidorphan are “consistent, regardless of the stage of illness,” Dr. Kahn added.
He presented the findings at the annual congress of the Schizophrenia International Research Society.
Potential benefit
“Early intervention with antipsychotic treatment is critical in shaping the course of treatment and the disease trajectory,” coinvestigator Christine Graham, PhD, with Alkermes, which manufactures the drug, told this news organization.
Olanzapine is a “highly effective antipsychotic, but it’s really avoided a lot in this population,” Dr. Graham said. Therefore, patients “could really stand to benefit” from a combination that delivers the same amount of antipsychotic effect, but “reduces the propensity” for clinically significant weight gain, she added.
Dr. Kahn noted in his meeting presentation that antipsychotics are the “cornerstone” of the treatment of serious mental illness, but that “many are associated with concerning weight gain and cardiometabolic effects.”
While olanzapine is an effective medication, it has “one of the highest weight gain” profiles of the available antipsychotics and patients early on in their illness are “especially vulnerable,” Dr. Kahn said.
Previous studies have shown the combination of olanzapine plus samidorphan is similarly effective as olanzapine, but is associated with less weight gain.
To determine its impact in recent-onset illness, the current researchers screened patients with schizophrenia, schizophreniform disorder, or bipolar I disorder. The patients were aged 16-39 years and had an initial onset of active phase symptoms less than 4 years previously. They had less than 24 weeks’ cumulative lifetime exposure to antipsychotics.
Participants were randomly assigned to receive olanzapine plus samidorphan or olanzapine alone for 12 weeks, and then followed up for safety assessment for a further 4 weeks.
A total of 426 patients were recruited and 76.5% completed the study. The mean age was 25.8 years, 66.2% were men, 66.4% were White, and 28.2% were Black.
The mean body mass index at baseline was 23.69 kg/m2. The most common diagnosis among the participants was schizophrenia (62.9%) followed by bipolar I disorder (21.6%).