Selegiline

What is Selegiline?

Selegiline is a selective monoamine oxidase-B (MAO-B) inhibitor primarily used to treat Parkinson’s disease and major depressive disorder. It belongs to a class of medications called monoamine oxidase inhibitors that work by blocking specific enzymes in the brain that break down important neurotransmitters. Selegiline is available in oral tablets, capsules, and transdermal patches depending on the condition being treated.

Uses

• Parkinson’s disease: Used as an adjunctive treatment alongside levodopa/carbidopa to improve motor symptoms and reduce “wearing-off” episodes
• Major depressive disorder: The transdermal patch formulation is approved for treating depression in adults when other treatments have been inadequate
• Early-stage Parkinson’s disease: May be used as monotherapy in newly diagnosed patients to delay the need for levodopa therapy
• Cognitive enhancement in Parkinson’s: May help improve some cognitive symptoms associated with Parkinson’s disease
• Neuroprotection: Some evidence suggests it may have protective effects on brain cells, though this remains under investigation

How it works

Selegiline works by selectively inhibiting monoamine oxidase type B (MAO-B), an enzyme that breaks down dopamine in the brain. By blocking this enzyme, selegiline increases the availability of dopamine, which is particularly important in Parkinson’s disease where dopamine-producing brain cells are damaged or lost. At higher doses or in patch form, it also affects other neurotransmitters like serotonin and norepinephrine, which contributes to its antidepressant effects.

Side effects

Common side effects:

• Nausea and vomiting
• Dizziness and lightheadedness
• Insomnia and sleep disturbances
• Dry mouth
• Headache
• Confusion or hallucinations (especially in elderly patients)
• Skin irritation (with transdermal patch)
• Abdominal pain

Serious side effects requiring immediate medical attention:

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• Severe increase in blood pressure (hypertensive crisis)
• Serotonin syndrome symptoms (fever, muscle rigidity, rapid heart rate)
• Severe mood changes or suicidal thoughts
• Severe skin reactions at patch application site
• Uncontrolled movements or worsening of Parkinson’s symptoms

Warnings and precautions

• Dietary restrictions: Patients using higher doses or transdermal patches must avoid foods high in tyramine (aged cheeses, cured meats, fermented foods) to prevent dangerous blood pressure spikes
• Pregnancy and breastfeeding: Should be used only when benefits clearly outweigh risks; consult healthcare provider before use during pregnancy or while breastfeeding
• Mental health monitoring: May increase risk of suicidal thoughts, particularly in young adults; requires close monitoring especially when starting treatment
• Liver function: Use with caution in patients with liver impairment; regular monitoring may be necessary
• Elderly patients: Increased risk of confusion, hallucinations, and falls; may require lower doses and closer monitoring

Interactions

• Antidepressants (SSRIs, SNRIs, tricyclics): Risk of serotonin syndrome; typically requires washout period between medications
• Meperidine and tramadol: Dangerous interaction that can cause severe reactions including coma; must be avoided completely
• Dextromethorphan (cough suppressant): Can cause serotonin syndrome; avoid concurrent use
• Sympathomimetics (decongestants, stimulants): Risk of severe blood pressure elevation
• Levodopa: May enhance side effects like dyskinesias; dosage adjustments often needed
• St. John’s Wort: Herbal supplement that increases serotonin syndrome risk
• Tyramine-rich foods: At higher doses, can cause dangerous blood pressure spikes
• Other MAO inhibitors: Concurrent use is contraindicated due to risk of severe reactions

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Dosage

For Parkinson’s disease, the typical oral dose is 5 mg twice daily taken with breakfast and lunch, or 10 mg once daily in the morning. For depression, the transdermal patch is usually started at 6 mg per 24 hours, applied daily to clean, dry skin. Dosage adjustments should be made gradually under medical supervision. Lower doses may be necessary in elderly patients or those with liver impairment. All dosing decisions should be individualized and determined by a qualified healthcare provider based on the patient’s specific condition, response to treatment, and other factors.

Sources: FDA DailyMed drug labels (public domain), BNF, WHO Essential Medicines List. This article is for informational purposes only and does not constitute medical advice. Always consult your healthcare provider before starting or stopping any medication.

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