Which medication is considered first-line therapy for a patient diagnosed with major depression?

Citalopram is recognized as a first-line therapy for patients diagnosed with major depression primarily due to its classification as a selective serotonin reuptake inhibitor (SSRI). SSRIs like citalopram have been thoroughly studied and shown to be effective in alleviating symptoms of depression while generally having a favorable side effect profile compared to older classes of antidepressants.

The efficacy of SSRIs stems from their ability to increase serotonin levels in the brain, which is often linked to mood regulation. Citalopram is particularly favored due to its tolerability and safety, making it suitable for a broad range of patients, including those who may have comorbid conditions or a history of medication intolerance.

Other medications listed, while they may be used in certain cases, are not considered first-line treatments. Amitriptyline, for example, is a tricyclic antidepressant that can have more significant side effects and toxicity in overdose, making it less desirable as a first choice. Olanzapine is an antipsychotic that may be used in cases of treatment-resistant depression or in combination with other antidepressants, rather than as a standalone first-line treatment. Phenelzine, a monoamine oxidase inhibitor (MAOI), is typically reserved