Which medication is primarily used as an anxiolytic agent?

Diazepam is primarily used as an anxiolytic agent because it belongs to the benzodiazepine class of medications, which are specifically indicated for the treatment of anxiety disorders. Benzodiazepines act by enhancing the effect of the neurotransmitter gamma-aminobutyric acid (GABA) in the brain, leading to a calming effect on the nervous system. This makes diazepam particularly effective for managing acute anxiety episodes as well as providing muscle relaxation and sedation.

While sertraline and fluoxetine are both antidepressants that belong to the selective serotonin reuptake inhibitor (SSRI) class, they are primarily prescribed for depression and anxiety disorders over the long term, not as first-line treatments for acute anxiety. Nortriptyline is a tricyclic antidepressant that is mainly used for depression and certain types of neuropathic pain, but it is not primarily utilized as an anxiolytic. Thus, diazepam stands out as the most appropriate medication for direct anxiolytic use among the options provided.