The medicine is commonly used across conditions involving episodic or fluctuating manifestations. It is relevant in contexts where additional symptomatic support is needed.

Selegiline is applied across domains where supportive symptom management is appropriate for Parkinson's disease and, in specific formulations, for major depressive disorder. The medicine may assist in managing symptoms of increased neurological or muscular activity and symptoms related to systemic imbalance.

Support for Symptom Management

In the context of Parkinson's disease, Selegiline is commonly used to help with the core symptoms of the condition, such as slowness and rigidity, particularly when symptoms are more noticeable. Its application in these stages provides a supportive benefit that generally assists with maintaining functional stability.

For patients already on primary symptomatic treatment, the medicine is used to address response variability where effective symptom control declines between doses. It helps address symptom clusters that may become intense or disruptive, contributing to improved comfort during periods of heightened symptoms and functional relief throughout the day. In a specialized context, the medicine is applied to address symptoms related to mood disturbances, providing symptomatic relief that generally supports the patient during difficult episodes by easing distress.

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Quick Fact: Supportive Relief for Symptoms

The medicine is relevant for managing symptoms related to movement and mood, which may interfere with daily functioning. It provides supportive relief when symptoms interfere with routine activities.

Regulatory References

1. NIH MedlinePlus overview

The eligibility for using Selegiline is strictly defined by regulatory authorities and is generally restricted to the adult population. Eligibility rules outline who is approved to use the medicine and who is formally prohibited, often depending on the specific formulation (oral tablet, capsule, or transdermal patch).

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Who Must Not Use Selegiline (Contraindications)

Official labeling states that Selegiline is contraindicated and must not be used by patients with:

• Known hypersensitivity to the drug or its components.
• An active duodenal or gastric ulcer (for oral forms).
• Pheochromocytoma (a specific adrenal gland tumor).
• Other extrapyramidal disorders not related to dopamine deficiency (for oral forms).
• Children and adolescents; safety and efficacy are not established in the pediatric population.

For oral Selegiline used with levodopa, additional contraindications may apply, including severe cardiovascular disease or uncontrolled hypertension.

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Conditional or Restricted Use

Use is not recommended in several populations due to insufficient safety data or altered metabolism:

• Severe hepatic or renal impairment (limitations apply to the Orally Disintegrating Tablet).
• Pregnancy and breastfeeding, as use is generally advised to be avoided. Caution is also noted for older adults (85 years and above) due to limited clinical experience.

Interactions with other medicines and products

Official regulatory documents define specific and rigorous restrictions regarding the co-administration of selegiline with certain medicines and substances.

Contraindicated Combinations

Co-administration is strictly prohibited with several medicinal product categories due to the risk of severe pharmacodynamic potentiation. These contraindicated agents include most Opioid Drugs (such as Meperidine and Tramadol), Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs), Selective Serotonin Reuptake Inhibitors (SSRIs), Tricyclic Antidepressants, and other Monoamine Oxidase Inhibitors (MAOIs). Additionally, Sympathomimetic medications, Dextromethorphan, and the herbal supplement St. John's Wort are also prohibited combinations.

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Pharmacokinetic and Timing Constraints

Other substances affect the exposure profile of selegiline. Concomitant use with oral contraceptives may increase selegiline's bioavailability. Conversely, substances that induce CYP2B6 (like Fexinidazole) may reduce its concentrations. Procedural rules are mandated for treatment switches; for instance, a minimum of 5 weeks must elapse when switching from Fluoxetine to selegiline. Conversely, at least 2 weeks must pass after stopping selegiline before starting any prohibited medicine. The transdermal patch formulation requires adherence to specific dietary restrictions concerning tyramine-rich foods due to the potential for Hypertensive Crisis, a risk that increases with high oral doses.

Selegiline acts primarily through the irreversible inhibition of the enzyme Monoamine Oxidase B ( MAO-B), which is predominantly located in glial cells and specific neurons within the central nervous system. This molecular action blocks the catabolic breakdown of specific monoamines, chiefly dopamine. This mechanism fundamentally serves to elevate and prolong functional dopamine concentration in the synapse, which sustains functional communication across the affected neural pathways.

The core action involves Selegiline's role as a suicide substrate that permanently deactivates MAO-B. The resulting sustained elevation of dopamine concentration modifies dopaminergic activity, influencing the dopaminergic pathways critical for motor circuitry function. Beyond this primary role, the mechanism also leads to the enhanced presence of trace amines like beta-phenethylamine, which indirectly modulate synaptic activity. Furthermore, by preventing the MAO-B-mediated breakdown of dopamine, Selegiline reduces the formation of toxic byproducts like hydrogen peroxide ( H2 O2). The reduction in oxidative chemical stress associated with dopamine metabolism may limit the burden on neuronal systems.

A key constraint of the mechanism is the dose-dependent nature of its selectivity. At concentrations exceeding the lower therapeutic range, Selegiline loses its specificity and begins to inhibit MAO-A. This expansion of the drug's target range influences additional monoamine pathways, affecting the overall balance of neurotransmitters by stabilizing levels of norepinephrine and serotonin alongside dopamine.

How Selegiline is Used: Administration and Usage

Selegiline is administered according to instructions that specify the route, dose, frequency, and conditions for use across its available forms. The medicine is primarily available for administration via the oral route (as tablets, capsules, and orally disintegrating tablets (ODT)) and the transdermal route (as a patch).

Standard Dosing and Frequency

Form	Typical Starting/Maintenance Dose	Frequency and Timing	Key Administration Condition
Conventional Oral Forms (Tablets/Capsules)	10 mg per day (often as 5 mg twice daily)	Twice daily (at breakfast and lunch)	Should be taken with food
Orally Disintegrating Tablets (ODT)	Starting: 1.25 mg once daily. Max: 2.5 mg once daily.	Once daily in the morning	Taken before breakfast and without liquid; avoid food/liquid for 5 minutes after
Transdermal Patch	Starting: 6 mg/24 hours system. Max: 12 mg/24 hours system.	Applied once every 24 hours	Requires site rotation; higher strengths (≥ 9 mg/24 hours) require tyramine-restricted diet

Procedural and Adjustment Rules

Established protocols define specific procedural constraints to ensure proper use:

• Titration: Dose increases for the ODT and the transdermal patch must follow minimum time intervals (e.g., 6 weeks for ODT, 2 weeks for the patch) before any adjustment is considered.
• Special Populations: The dose of the ODT should be reduced (e.g., to 1.25 mg daily) in patients who have been diagnosed with mild to moderate hepatic impairment.

Research Evidence / Overview of Studies for Selegiline

Evidence for Use in Parkinson's Disease

Research involving Selegiline has explored two main scenarios: use in adults with early Parkinson's disease (PD) and use later, in conditions characterized by fluctuating or episodic manifestations. Studies monitored groups of adults with newly diagnosed, untreated PD in randomized controlled trials (RCTs). In these settings, research examined outcomes related to how symptoms evolved in the observed populations, specifically measuring changes in standardized motor symptom rating scales.

For individuals with more advanced PD who were already taking levodopa, studies were conducted during periods of increased symptom activity. These studies monitored outcomes related to episodic or acute changes in symptoms, such as the daily duration of motor "off" time.

Evidence for Use in Major Depressive Disorder

Research on Selegiline was studied for major depressive disorder (MDD), and the primary evidence is specific to the transdermal patch formulation. Studies for this use involved short-term randomized, controlled trials, which included adult outpatients. The research examined changes from the start of the study, and also studies explored the number of people who met specific criteria for outcomes reflecting daily functioning or activity level or a specific reduction in symptom measures.

Long-Term Studies and Follow-Up Data

For both Parkinson's disease and major depressive disorder, the long-term effects are not fully established beyond the periods covered by the primary clinical trials. Research exploring how symptoms evolved in the observed populations over longer intervals is available but findings were mixed, meaning that evidence quality varies across studies when assessing long-term follow-up.

What is Still Uncertain About Selegiline

The current research highlights several areas where further investigation is needed. Long-term outcomes are not well characterized regarding outcomes reflecting daily functioning or activity level in Parkinson's disease. Comparative evidence is limited in large-scale, head-to-head trials against all other contemporary treatments for both indications. Furthermore, research does not determine whether an individual will respond similarly to the group patterns observed in studies, and findings describe group patterns, not personal outcomes.

Key Studies & References

1. Efficacy and safety of selegiline across different psychiatric disorders: A systematic review and meta-analysis of oral and transdermal formulations

Common questions about Selegiline (FAQ)

Q: What is Selegiline used for?

A: Selegiline is a medication approved by the U.S. Food and Drug Administration (FDA) for use as an adjunct (add-on) treatment for symptoms of Parkinson's disease in patients who are already taking levodopa and carbidopa. It is used when the effects of levodopa/carbidopa begin to wear off.

It is also approved in a transdermal patch formulation for the treatment of major depressive disorder (MDD) in adults.

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Q: How is Selegiline classified as a drug?

A: Selegiline is classified as a monoamine oxidase B (MAO-B) inhibitor. It affects the function of an enzyme known as monoamine oxidase, which is involved in breaking down certain chemicals in the brain, including dopamine.

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Q: What are the potential side effects of taking Selegiline?

A: Common side effects reported during clinical studies may include:

• Nausea
• Dizziness or lightheadedness, particularly when standing up
• Dry mouth
• Difficulty sleeping (insomnia)
• Stomach pain or discomfort
• Constipation

Serious side effects may occur, including high blood pressure (hypertension), fainting, or uncontrolled movements (dyskinesia). A healthcare provider should be contacted immediately if a patient experiences confusion, hallucinations, or signs of a serious reaction, such as a severe headache.

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Q: Can Selegiline be taken with other medications?

A: Selegiline may interact with many other medications, and some combinations are considered dangerous. It is essential to inform your healthcare provider of all prescription and non-prescription drugs, supplements, and herbal products currently being taken.

Specific drug types that may pose a risk include:

• Certain antidepressants (including SSRIs and tricyclics)
• Other MAO inhibitors
• Narcotic pain medications (such as meperidine and tramadol)
• St. John's wort
• Certain cold or cough remedies containing dextromethorphan or pseudoephedrine

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Q: Are there any dietary restrictions when taking Selegiline?

A: Certain foods and drinks that contain high levels of a substance called tyramine may cause a dangerous increase in blood pressure (hypertensive crisis) when taken with Selegiline. The risk is generally considered low at the doses typically used for Parkinson's disease. However, the risk increases with higher doses, such as those used for depression treatment or in the transdermal patch.

Patients should discuss their diet with their healthcare provider or pharmacist, who may provide a list of high-tyramine foods to be avoided, such as aged cheeses, cured meats, and certain alcoholic beverages.

How to Store and Dispose of Selegiline

Official regulatory information requires specific storage and disposal practices to maintain product safety and efficacy.

Storage and Handling

Requirement	Official Instruction
Temperature	Store at controlled room temperature, typically 15 C to 30 C (59 F to 86 F).
Protection	Keep the medicine in its original, tightly closed container, protected from excessive heat, freezing, moisture, and direct light.
Specific Forms	Orally disintegrating tablets must be handled with dry hands and remain in their blister pack until use. Discard this form three months after opening the protective pouch.

Disposal and Safety

Used or outdated Selegiline should be disposed of according to the advice of a healthcare professional or pharmacist. The product must be stored up and away, out of the sight and reach of children. Used transdermal patches should be folded in half, sticky sides together, prior to safe disposal.