Which of the following medications is least likely to lead to depression?

Desvenlafaxine is an antidepressant that works by affecting neurotransmitters in the brain, specifically serotonin and norepinephrine. As a treatment for major depressive disorder, it is designed to alleviate symptoms of depression rather than contribute to them. Its primary function is to improve mood and emotional well-being, making it least likely to lead to depression compared to the other options listed.

In contrast, beta-blockers are primarily used for cardiovascular conditions but can have side effects that may include depression in some patients. Sedatives, which act to calm the central nervous system, may also lead to mood changes or depressive symptoms as a secondary effect. Chemotherapy agents can have a significant emotional toll and may contribute to feelings of depression due to their physical side effects and the stress associated with cancer treatment. Therefore, while all medications carry some risk of side effects, desvenlafaxine stands out as the option least associated with an increased likelihood of depression.