Neuropsychiatric Side Effects Reported With CB1 Weight-Loss Drug
Monlunabant, a small molecule oral cannabinoid receptor 1 (CB1) inverse agonist, was associated with statistically significant weight loss at all doses in people with obesity and metabolic syndrome, but the drug was also linked with mild to moderate neuropsychiatric side effects, Novo Nordisk announced.
The findings stem from a phase 2a clinical trial that investigated the efficacy and safety of once-daily monlunabant at doses of 10 mg, 20 mg, and 50 mg compared with placebo. The 16-week study included 243 people with obesity and metabolic syndrome who were randomized equally to the 4 treatment arms. Average body weight at baseline was 242.7 pounds.
All patient groups that received monlunabant demonstrated statistically significant weight loss compared with the placebo group. The 10-mg monlunabant group showed a 15.65-pound average weight loss compared with 1.54 pounds with placebo. Higher doses of monlunabant were linked with “limited additional weight loss,” Novo Nordisk said.
Reports of mild to moderate neuropsychiatric side effects — primarily anxiety, irritability, and sleep disturbances — were more frequent with monlunabant than placebo. Neuropsychiatric side effects were dose dependent, and no related serious adverse events were reported. The most common adverse events with monlunabant were gastrointestinal, the company stated.
“The phase 2a results indicate the weight-lowering potential of monlunabant and that further work is needed to determine the optimal dosing to balance safety and efficacy,” said Martin Holst Lange, executive vice president and head of development at Novo Nordisk.
The company plans to launch a larger, global phase 2b trial in 2025 to further investigate monlunabant dosing and safety over a longer duration.
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