Which of the following is recognized as a selective serotonin reuptake inhibitor (SSRI)?

• A. Cylert
• B. Ritalin
• C. Prozac
• D. Valium

Answer: (C)

Prozac is recognized as a selective serotonin reuptake inhibitor (SSRI) because it works primarily by inhibiting the reuptake of serotonin in the brain, thereby increasing the levels of serotonin available to bind to postsynaptic receptors. This mechanism is fundamental to its effectiveness in treating conditions such as depression and anxiety, as enhancing serotonin transmission is thought to help improve mood and anxiety symptoms. SSRIs are known for their selectivity in targeting serotonin reuptake, which contributes to their generally favorable side effect profile compared to older antidepressants that impact multiple neurotransmitters.

In contrast, the other substances listed do not function as SSRIs. Cylert is primarily used to treat attention deficit hyperactivity disorder (ADHD) and works as a central nervous system stimulant. Ritalin, also used for ADHD, affects dopamine and norepinephrine and is categorized as a stimulant rather than an SSRI. Valium is a benzodiazepine that acts on the gamma-aminobutyric acid (GABA) receptor system, promoting relaxation and sedation, rather than influencing serotonin levels. This distinction helps clarify why Prozac stands out as the only SSRI in the provided options.