In pharmacologic options for weight management, which drug is not approved due to low efficacy?

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

Answer: (C)

When evaluating drugs for weight management, the key factor is whether the medicine produces meaningful, durable weight loss with an acceptable safety profile. Lisdexamfetamine, a stimulant prodrug used for ADHD and binge eating disorder, has not shown the level of weight loss in obesity trials needed to support approval for weight management, and safety concerns with stimulants (including potential for misuse) further limit its use for obesity. The other options have demonstrated more robust, clinically meaningful weight loss and are approved for chronic weight management: orlistat works by blocking fat absorption and yields modest but durable weight loss; liraglutide at the higher obesity dose produces substantial weight loss and metabolic benefits; phentermine provides short-term appetite suppression with approval for limited duration.