Which of the following medications is NOT approved for the treatment of generalized anxiety disorder (GAD)?

Clonazepam is primarily classified as a benzodiazepine, which is typically used for short-term management of anxiety symptoms and not specifically approved for the treatment of generalized anxiety disorder (GAD) by regulatory authorities. While benzodiazepines like clonazepam can provide rapid relief from acute anxiety, they are not recommended for long-term management due to the potential for dependence, tolerance, and withdrawal issues.

In contrast, the other medications listed are all considered first-line treatments for GAD. Duloxetine, venlafaxine, and escitalopram are approved for this condition and have demonstrated efficacy through various clinical studies. These medications belong to different classes of antidepressants—serotonin-norepinephrine reuptake inhibitors (Duloxetine, Venlafaxine) and selective serotonin reuptake inhibitors (Escitalopram)—and are utilized for their ability to improve anxiety symptoms in a sustained manner without the risks associated with benzodiazepines. Thus, clonazepam stands out as the unsuitable option for the long-term treatment of GAD.