Which of the following medications is commonly prescribed as a mood stabilizer?

Valproate is commonly prescribed as a mood stabilizer, particularly for individuals with bipolar disorder. Its ability to stabilize mood is attributed to its effects on neurotransmitter systems, including the modulation of glutamate and gamma-aminobutyric acid (GABA). Valproate helps prevent severe mood swings, which are characteristic of bipolar disorder, and is often used in both acute manic episodes and for long-term management of mood stability.

While Sertraline, Risperidone, and Fluoxetine can be used in treating various mood disorders, they serve different primary purposes. Sertraline and Fluoxetine are selective serotonin reuptake inhibitors (SSRIs) primarily used as antidepressants rather than mood stabilizers. Risperidone is primarily an atypical antipsychotic that may be used to manage symptoms of mania in bipolar disorder but is not classified as a mood stabilizer in the same way that valproate is. Thus, Valproate stands out as the medication that fulfills the role of a mood stabilizer effectively.