The FDA has approved EMSAM (selegiline), a transdermal patch, for the treatment of major depression. Selegeline is a MAOI originally used to treat Parkinson’s. MAOIs belong to an old class of antidepressants, typically used as a last resort. When taken orally, side effects with these meds tend to be onerous, including risk of tyramine reaction and resulting hypertensive crisis, which necessitates severely restricting one’s diet.

The patch was developed by Somerset Pharmaceuticals,...