1. Clinical Overview
Rasagiline is a potent, irreversible, and selective monoamine oxidase-B (MAO-B) inhibitor used primarily as monotherapy or adjunctive therapy in the treatment of Parkinson's disease (PD). It enhances dopaminergic neurotransmission in the striatum by reducing the metabolic breakdown of dopamine. The 0.5mg dose is the standard starting and often maintenance dose for monotherapy in early PD, offering symptomatic control with a favorable side effect profile compared to older agents.
| Onset | Duration | Bioavailability |
|---|---|---|
| Clinical improvement in motor symptoms may be observed within 1-2 weeks of initiation, though maximal therapeutic effect can take several weeks. | Due to its irreversible inhibition of MAO-B, the pharmacological effect persists beyond its plasma half-life, lasting for the lifespan of the enzyme (up to 40 days). Symptomatic control is maintained with once-daily dosing. | Approximately 36%. |
2. Mechanism of Action
Rasagiline irreversibly and selectively inhibits the enzyme monoamine oxidase type B (MAO-B) in the brain. MAO-B is responsible for the catabolism of dopamine. By inhibiting this enzyme, rasagiline increases the availability of synaptic dopamine in the striatum, thereby improving the dopaminergic neurotransmission that is deficient in Parkinson's disease.
3. Indications & Uses
- Idiopathic Parkinson's Disease: Monotherapy in early-stage disease to treat motor symptoms (bradykinesia, rigidity, tremor).
- Idiopathic Parkinson's Disease: Adjunctive therapy to levodopa/carbidopa in patients with motor fluctuations (end-of-dose 'wearing off').
4. Dosage & Administration
Adult Dosage: Parkinson's Disease Monotherapy: 0.5 mg orally once daily. Parkinson's Disease Adjunctive to Levodopa: 0.5 mg orally once daily. May be increased to 1 mg once daily based on clinical response and tolerability.
Administration: Administer orally, with or without food, at the same time each day. Tablet should be swallowed whole with water. If a dose is missed, take the next dose at the usual time the next day; do not double the dose.
5. Side Effects
Common side effects may include:
- Headache
- Dizziness
- Nausea
- Orthostatic hypotension (dizziness on standing)
- Arthralgia (joint pain)
- Dyspepsia
- Depression
6. Drug Interactions
| Drug | Effect | Severity |
|---|---|---|
| Other MAO Inhibitors (e.g., Selegiline, Phenelzine, Isocarboxazid, Linezolid) | Risk of severe hypertensive crisis, hyperpyrexia, serotonin syndrome. | Contraindicated |
| Pethidine (Meperidine), Tramadol, Methadone, Dextromethorphan | Risk of serotonin syndrome, hyperpyrexia, cardiovascular instability. | Contraindicated |
| Selective Serotonin Reuptake Inhibitors (SSRIs: Citalopram, Escitalopram, Fluoxetine, Paroxetine, Sertraline) | Increased risk of serotonin syndrome. | Avoid / Use with extreme caution |
| Serotonin-Norepinephrine Reuptake Inhibitors (SNRIs: Venlafaxine, Duloxetine) | Increased risk of serotonin syndrome. | Avoid / Use with extreme caution |
| Tricyclic Antidepressants (TCAs: Amitriptyline, Imipramine) | Increased risk of serotonin syndrome and CNS toxicity. | Avoid / Use with extreme caution |
| Cyclobenzaprine | Risk of serotonin syndrome. | Avoid |
| Sympathomimetics (e.g., Ephedrine, Pseudoephedrine, Phenylephrine in cold remedies) | Exaggerated pressor response, risk of hypertensive crisis. | Avoid |
| Ciprofloxacin, other CYP1A2 inhibitors | May increase rasagiline plasma levels. Dose should not exceed 0.5 mg/day. | Moderate |
7. Patient Counselling
- DO take the tablet at the same time every day, with or without food.
- DO inform all your healthcare providers (doctors, dentists, surgeons) that you are taking rasagiline.
- DO report any new or worsening symptoms like dizziness on standing, hallucinations, depression, or skin changes/moles immediately.
- DO NOT take any other prescription, over-the-counter (OTC), or herbal medicine (especially cough/cold remedies, antidepressants, painkillers like tramadol/dextromethorphan) without consulting your doctor.
- DO NOT consume very large amounts of aged cheeses, fermented meats (salami), soy sauce, or tap beer in one sitting. Normal dietary amounts are acceptable.
8. Toxicology & Storage
Overdose: Symptoms may include severe hypertension (hypertensive crisis), severe serotonin syndrome (agitation, confusion, hyperthermia, tachycardia, rigidity), drowsiness, dizziness, and severe headache.
Storage: Store at room temperature (15°C to 30°C). Protect from light and moisture. Keep the bottle tightly closed. Keep out of reach of children.