Which antidepressant is commonly added to treatment when patients are nonresponsive?

In cases where a patient is nonresponsive to standard antidepressant treatments, particularly selective serotonin reuptake inhibitors (SSRIs), lithium is often considered as an augmentation strategy. Lithium has mood-stabilizing properties and has been shown to enhance the effectiveness of antidepressants in patients with treatment-resistant depression. This is especially relevant in situations where depression may have features of bipolar disorder, as lithium not only helps elevate mood but also can stabilize mood swings.

Augmentation with lithium is supported by several studies that document its efficacy in improving the response rates of patients who have not adequately responded to standard antidepressant therapies. This characteristic makes it a valuable option in a clinical setting when addressing treatment-resistant depression.

The other options, while they may have their specific clinical roles, do not align with commonly accepted augmentation strategies for nonresponsive depression in the same way. Antipsychotics can be used in certain resistant cases, particularly when symptoms are severe or include psychosis. However, they are not as universally recognized or utilized as lithium for augmenting antidepressant therapy. Opioids have no role in the treatment of depression and could potentially exacerbate the situation. Therefore, lithium stands out as the most appropriate option when patients show a lack of response to their initial antidepressant treatment.