Selegiline is a selective, irreversible inhibitor of monoamine oxidase type B (MAO-B) used primarily as an adjunctive therapy in the management of Parkinson's disease. At the low dose of 5mg, it is selective for MAO-B, but at higher doses (>10mg/day), it loses selectivity and inhibits MAO-A, requiring strict dietary tyramine restrictions (the 'cheese effect'). In the Indian context, it is a key component of Parkinson's therapy to potentiate levodopa effects and reduce 'wearing-off' phenomena.
Adult: Parkinson's disease (adjunct to levodopa): 5 mg orally twice daily, typically with breakfast and lunch. Monotherapy: 5 mg once or twice daily. Maximum recommended selective dose: 10 mg per day in divided doses.
Note: Take with or without food. To minimize insomnia, avoid taking the second dose later than mid-afternoon (e.g., no later than 2 PM). Swallow tablet whole with water. Do not crush or chew unless specified (some brands may be scored). Do not exceed prescribed dose.
Selegiline irreversibly and selectively inhibits monoamine oxidase type B (MAO-B) at low doses. MAO-B is responsible for the metabolism of dopamine in the striatum. By inhibiting MAO-B, selegiline increases synaptic dopamine concentrations, thereby enhancing and prolonging the therapeutic effect of endogenous and exogenous (levodopa-derived) dopamine. This helps manage motor symptoms of Parkinson's disease.
Pregnancy: Category C (US FDA). Animal studies have shown adverse effects. There are no adequate and well-controlled studies in pregnant women. Use only if the potential benefit justifies the potential risk to the fetus. Should not be used during pregnancy unless clearly necessary for Parkinson's disease management.
Driving: May cause dizziness, lightheadedness, or sudden episodes of drowsiness/sleep onset ('sleep attacks'), which can impair the ability to drive or operate machinery. Patients should be cautioned until they know how the medication affects them.
| Levodopa/Carbidopa | Potentiates levodopa effect, increasing dyskinesias and psychiatric side effects. Levodopa dose often needs reduction by 10-30%. | Major |
| Selective Serotonin Reuptake Inhibitors (SSRIs: Fluoxetine, Sertraline, etc.) | Risk of serotonin syndrome. A long washout period (5 weeks for fluoxetine, 2 weeks for others) is required. | Contraindicated/Major |
| Tricyclic Antidepressants (TCAs: Amitriptyline, Imipramine) | Risk of serotonin syndrome and hypertensive crisis. | Contraindicated/Major |
| Pethidine (Meperidine) | Life-threatening serotonin syndrome, hyperpyrexia, coma. | Contraindicated |
| Sympathomimetics (Pseudoephedrine, Ephedrine) | Exaggerated pressor response, hypertensive crisis. | Contraindicated/Major |
| Tyramine-rich foods (Aged cheese, cured meats, fermented products) | At doses >10mg/day, risk of hypertensive crisis ('cheese reaction'). At 5mg, risk is minimal but caution advised. | Moderate (at selective doses) |
| Ciprofloxacin, Cimetidine | Inhibit CYP1A2/CYP3A4, may increase selegiline levels. | Moderate |
| Rifampicin, Carbamazepine | Induce CYP enzymes, may decrease selegiline levels. | Moderate |