Which medication is not an example of a tricyclic antidepressant?

Wellbutrin, known generically as bupropion, is not classified as a tricyclic antidepressant (TCA). Instead, it belongs to a different category of antidepressants known as norepinephrine-dopamine reuptake inhibitors (NDRIs). This medication works by targeting the neurotransmitters norepinephrine and dopamine, differing fundamentally from TCAs, which primarily function by inhibiting the reuptake of norepinephrine and serotonin.

TCAs, such as Tofranil (imipramine), Sinequan (doxepin), and Vivactil (protriptyline), share a common chemical structure characterized by three interconnected rings. This structural feature is critical to their classification and influences their pharmacological effects, which include a broader range of side effects due to their interaction with various neurotransmitter systems and receptors.

In summary, Wellbutrin is distinct from TCAs in both its mechanism of action and its chemical structure, making it the correct choice as the medication that is not an example of a tricyclic antidepressant.