BLACK BOX WARNING
- suicidality in children, adolescents, and young adults
selegiline (transdermal patch for depression)
Brand: Emsam
⚠ BBW Prototype: phenelzine
Drug Class: monoamine oxidase inhibitor (MAOI)
Drug Family: antidepressant
Subclass: irreversible MAO-B selective (selective at low doses; non-selective at patch doses)
Organ Systems: cns
Mechanism of Action
At low oral doses (5 mg), selectively inhibits MAO-B (relevant to Parkinson's); at transdermal patch doses (6-12 mg/24h), plasma levels are high enough to inhibit both MAO-A and MAO-B in the brain without significantly inhibiting intestinal MAO-A, which may reduce tyramine interaction risk at the 6 mg dose.
MAO-B (monoamine oxidase B)MAO-A (monoamine oxidase A, at higher doses)
Indications
- major depressive disorder (transdermal patch only)
- Parkinson's disease (oral; separate entry)
Contraindications
- concurrent serotonergic drugs
- concurrent sympathomimetics
- concurrent dextromethorphan
- concurrent meperidine
Adverse Effects
Common
- application site reactions
- insomnia
- diarrhea
- dry mouth
- weight loss
Serious
- hypertensive crisis (lower risk at 6 mg patch without dietary restriction)
- serotonin syndrome
Pharmacokinetics (ADME)
| Absorption | transdermal patch bypasses first-pass intestinal metabolism; systemic bioavailability ~73% via patch |
| Distribution | widely distributed; crosses BBB |
| Metabolism | metabolized to L-amphetamine and L-methamphetamine (minor metabolites via CYP enzymes) |
| Excretion | primarily renal |
| Half-life | 18-25 hours (transdermal) |
| Onset | antidepressant 2-4 weeks |
| Peak | approximately 15 hours (transdermal) |
| Duration | 24 hours per patch |
| Protein Binding | ~90% |
| Vd | not well characterized |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| SSRIs, SNRIs, TCAs, tramadol, meperidine | serotonin syndrome | contraindicated |
| sympathomimetics | hypertensive crisis | contraindicated |
| tyramine-rich foods | hypertensive crisis (dietary restriction required for 9 mg and 12 mg patches but NOT the 6 mg patch per FDA labeling) | major |
Nursing Considerations
- The 6 mg/24h transdermal patch is the only MAOI that does not require dietary tyramine restriction at its starting dose; however, 9 mg and 12 mg patches require full tyramine dietary restriction.
- Apply the patch to dry, intact skin on the upper torso, outer upper arm, or upper thigh; rotate application sites daily; avoid heat sources over the patch (increases drug absorption unpredictably).
- Instruct patient about a 14-day washout period before starting any serotonergic medication after patch discontinuation; provide written washout instructions.
- Insomnia is more common than with phenelzine due to dopaminergic activation; recommend consistent bedtime routine and avoidance of patch application near bedtime.
Clinical Pearls
- The transdermal delivery of selegiline for depression was developed specifically to bypass intestinal MAO-A inhibition, thereby allowing the 6 mg dose to be used without dietary tyramine restriction — representing a pharmacokinetic solution to a pharmacodynamic safety problem.
- Unlike oral selegiline used in Parkinson's disease (which selectively inhibits MAO-B at low doses), the transdermal patch delivers sufficient systemic drug to inhibit both MAO-A and MAO-B in the brain, which is necessary for antidepressant efficacy.
Safety Profile
Pregnancy avoid
Lactation avoid
Renal Adjustment Not required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
Cross-referenced clinical concepts — click any term to see all content where it appears.