Which of the following drugs is not approved for weight management because of its low efficacy?

• A. Phentermine
• B. Orlistat
• C. Lisdexamfetamine
• D. Liraglutide

Answer: (C)

Weight-management medications are approved based on clear evidence of meaningful, sustained weight loss and a acceptable safety profile. Among the options, the stimulant lisdexamfetamine is not approved for weight management because its demonstrated benefit for reducing body weight in obesity trials is not strong enough to justify use for this purpose, and stimulants carry safety and misuse concerns that further limit their suitability for obesity treatment.

Phentermine, orlistat, and liraglutide have been evaluated with weight-loss outcomes that meet regulatory standards for pediatric obesity treatment, offering more reliable weight reduction and approved indications. Lisdexamfetamine, while useful for ADHD and sometimes for binge eating disorder, does not carry a label for obesity management due to the combination of limited efficacy in this specific indication and safety considerations.