Which of the following is a tricyclic antidepressant?

• A. Amitriptyline
• B. Promethazine
• C. Chlorpheniramine
• D. Diazepam

Answer: (A)

Tricyclic antidepressants are older antidepressants characterized by a three-ring chemical structure and their primary action of blocking the reuptake of norepinephrine and serotonin, increasing these neurotransmitters in the synapse. Amitriptyline is a classic example of a tricyclic antidepressant, so it fits the category here.

Promethazine and chlorpheniramine are antihistamines (H1 blockers) with sedative properties, not antidepressants. Diazepam is a benzodiazepine, used for anxiety and seizure disorders, not an antidepressant.