MAOIs and transdermal delivery.

Although not currently considered a first-line treatment for depression due to safety and tolerability concerns, MAOIs are effective antidepressants, particularly for atypical or treatment-resistant depression. FDA-approved oral MAOIs inhibit both MAO-A and MAO-B; inhibition of MAO-A in the brain is required for an antidepressant effect, but inhibition in the intestinal tract can allow excessive absorption of tyramine, which can lead to hypertensive crisis. A transdermal formulation of selegiline delivers the medication directly into the circulatory system, bypassing the first-pass metabolism of the GI system and substantially reducing the risk for tyramine-related adverse events. The skin patch allows for a lower dose of the drug to achieve an antidepressant effect, maintains a steady dose of the medication over 24 hours, and avoids the need for dietary restrictions at the minimum effective dose of 6 mg/24 hours. MAOIs are useful treatment options for patients who have not responded to first-line treatments, and understanding their mechanism of action can help clinicians to accurately and safely prescribe these medications.