Switching antidepressants in adult patients with unipolar major depression of mild to moderate severity that does not respond to initial treatment with a selective serotonin reuptake inhibitor (SSRI) and subsequent augmentation

SSRI: selective serotonin reuptake inhibitor; SNRI: serotonin-norepinephrine reuptake inhibitor; MAOI: monoamine oxidase inhibitor.
* Mild to moderate unipolar major depression is indicated by a score of <20 points on the Patient Health Questionnaire – Nine Item (PHQ-9). Response is defined as reduction of baseline symptoms ≥50%; implicit in response is that the patient tolerates the treatment option. Patients not achieving response are often referred to clinicians who specialize in treatment resistant depression. The duration of an adequate trial for each treatment option below is generally 6 to 12 weeks. However, for patients who show little improvement (eg, reduction of baseline symptoms <25%) after 4 to 6 weeks, it is reasonable to administer next-step treatment. If patients progress to severe depression, different treatments are indicated. Refer to UpToDate topic for treatment-resistant depression.
¶ Refer to UpToDate topic on maintenance treatment of unipolar major depression.
Δ When switching from one drug to another, the drugs are usually cross tapered. If insufficient response occurs at the minimal therapeutic dose for the new drug, the dose is titrated up within the therapeutic range during the drug trial. Doses that achieve response are maintained. Refer to UpToDate topic on switching antidepressants.
◊ At any point in this pathway, it is reasonable to switch to psychotherapy or transcranial magnetic stimulation. Refer to UpToDate topic on treatment-resistant depression for information on how to decide to switch to psychotherapy or transcranial magnetic stimulation.
§ Switching to MAOIs requires dietary restrictions and caution regarding drug-drug interactions. Refer to UpToDate topics on switching antidepressants and on MAOIs.
¥ Refer to UpToDate topic on highly resistant (refractory) depression.