AZILECT: Uses, Dosage & Side Effects

What Is AZILECT and What Is It Used For?

AZILECT contains the active substance rasagiline (as rasagiline mesylate), a propargylamine derivative that functions as a potent, selective, and irreversible inhibitor of monoamine oxidase type B (MAO-B). MAO-B is one of two isoforms of the monoamine oxidase enzyme family, and it plays a central role in the oxidative deamination of dopamine within the brain. In the striatum, the brain region most severely affected in Parkinson's disease, MAO-B is responsible for approximately 80% of dopamine metabolism. By permanently inactivating MAO-B through the formation of a covalent bond with the flavin adenine dinucleotide (FAD) cofactor at the enzyme's active site, rasagiline effectively prevents dopamine degradation and increases its synaptic availability.

Parkinson's disease is a progressive neurodegenerative disorder characterized by the loss of dopaminergic neurons in the substantia nigra pars compacta of the midbrain. This neuronal loss leads to a profound deficit of dopamine in the striatum, which manifests clinically as the cardinal motor symptoms of the disease: resting tremor, rigidity, bradykinesia (slowness of movement), and postural instability. The disease affects approximately 1–2% of the population over the age of 60 worldwide, with prevalence increasing with age. The World Health Organization estimates that the global burden of Parkinson's disease has more than doubled in the past 25 years, and it now affects over 8.5 million people worldwide.

By inhibiting MAO-B, rasagiline increases the concentration of dopamine in the synaptic cleft, thereby partially compensating for the dopaminergic deficit that underlies the motor symptoms of Parkinson's disease. In addition to its enzyme-inhibitory activity, rasagiline and its major metabolite 1-aminoindan have been investigated for potential neuroprotective properties. Preclinical studies have suggested that rasagiline may activate anti-apoptotic pathways (including upregulation of Bcl-2 and Bcl-xL proteins), stabilize the mitochondrial membrane potential, and reduce oxidative stress. While the clinical significance of these neuroprotective effects in humans remains an area of active research, the ADAGIO (Attenuation of Disease Progression with Azilect Given Once-daily) trial provided some evidence that early initiation of rasagiline at 1 mg daily may have disease-modifying effects, though the results were complex and not conclusive.

AZILECT is approved for two primary indications in the management of Parkinson's disease:

• Monotherapy: AZILECT can be used as an initial treatment in patients with early-stage Parkinson's disease who have not yet started levodopa therapy. As monotherapy, it provides modest but clinically meaningful improvements in motor function as measured by the Unified Parkinson's Disease Rating Scale (UPDRS). The TEMPO (TVP-1012 in Early Monotherapy for Parkinson's Disease Outpatients) trial demonstrated that rasagiline 1 mg daily significantly improved total UPDRS scores compared to placebo over 26 weeks of treatment.
• Adjunct therapy with levodopa: AZILECT can be added to levodopa-based regimens in patients with more advanced Parkinson's disease who experience motor fluctuations (periods of reduced medication effectiveness known as “off” episodes). The PRESTO (Parkinson's Rasagiline: Efficacy and Safety in the Treatment of “Off”) and LARGO (Lasting effect in Adjunct therapy with Rasagiline Given Once daily) trials demonstrated that rasagiline 1 mg daily, when added to levodopa, significantly reduced total daily “off” time by approximately 0.94 hours compared to placebo, while increasing “on” time without troublesome dyskinesia.

AZILECT was first approved by the European Medicines Agency (EMA) in 2005 and by the U.S. Food and Drug Administration (FDA) in 2006. It is now approved in more than 50 countries worldwide. Rasagiline represents a second-generation MAO-B inhibitor, offering advantages over the older compound selegiline in that it does not produce amphetamine-like metabolites and has more predictable pharmacokinetics. International guidelines from the Movement Disorder Society (MDS), the National Institute for Health and Care Excellence (NICE), and the American Academy of Neurology (AAN) all recognize MAO-B inhibitors including rasagiline as appropriate first-line or adjunctive treatments for Parkinson's disease.

What Should You Know Before Taking AZILECT?

Contraindications

AZILECT must not be used in several clearly defined situations. The primary contraindication is known hypersensitivity (allergy) to rasagiline or to any of the excipients in the formulation. Patients with a history of allergic reactions to the inactive ingredients, including mannitol, maize starch, pregelatinized maize starch, colloidal anhydrous silica, stearic acid, and talc, should not take AZILECT.

Concomitant use with other monoamine oxidase inhibitors (including other MAO-B inhibitors such as selegiline and safinamide, and MAO-A inhibitors such as moclobemide) is contraindicated due to the risk of non-selective MAO inhibition, which could lead to hypertensive crisis. At least 14 days must elapse between discontinuation of AZILECT and initiation of another MAO inhibitor, and vice versa. Additionally, concomitant use with the following medications is contraindicated:

• Meperidine (pethidine): Risk of severe, potentially fatal reactions including serotonin syndrome, rigidity, hyperthermia, and cardiovascular collapse. At least 14 days must elapse between stopping AZILECT and starting meperidine.
• Tramadol: Similar risk of serotonin syndrome-like reactions due to tramadol's serotonergic properties.
• Methadone: Risk of serious adverse reactions including serotonin syndrome.
• Dextromethorphan: Risk of psychosis or bizarre behavior due to enhanced serotonergic effects. This cough suppressant is found in many over-the-counter cold preparations.
• St. John's wort (Hypericum perforatum): Risk of serotonin syndrome due to serotonin reuptake inhibition properties.
• Cyclobenzaprine: Structurally related to tricyclic antidepressants, carries risk of serotonergic interactions.

Patients with severe hepatic impairment (Child-Pugh Class C) must not use AZILECT due to significantly increased drug exposure resulting from impaired metabolism. In patients with moderate hepatic impairment (Child-Pugh Class B), AZILECT should be used with caution, and the clinical benefit should be carefully weighed against the potential risks.

Warnings and Precautions

Before starting AZILECT, several important precautions should be discussed with your healthcare provider. While rasagiline is a selective MAO-B inhibitor at the recommended dose of 1 mg daily, selectivity for MAO-B over MAO-A is dose-dependent and may be lost at doses exceeding the recommended amount. Exceeding the maximum recommended dose increases the risk of non-selective MAO inhibition, which could lead to dangerous hypertensive reactions with tyramine-containing foods.

• Orthostatic hypotension: Rasagiline may potentiate the hypotensive effects of levodopa and other antiparkinsonian medications, leading to dizziness or lightheadedness upon standing. This risk is higher during the initial period of treatment and in elderly patients. Patients should be advised to rise slowly from sitting or lying positions and to report symptoms of dizziness to their healthcare provider.
• Dyskinesia: When used as adjunct therapy with levodopa, rasagiline may increase the occurrence of dyskinesia (involuntary movements). A reduction in levodopa dose may help manage this side effect. In clinical trials, the incidence of dyskinesia was higher in patients receiving rasagiline plus levodopa compared to placebo plus levodopa.
• Impulse control disorders: As with other dopaminergic medications, rasagiline may be associated with impulse control disorders including pathological gambling, hypersexuality, compulsive spending, and binge eating. Patients and caregivers should be made aware of these potential behavioral changes and should report any such symptoms to their doctor.
• Melanoma risk: Patients with Parkinson's disease have an approximately two to six-fold higher risk of developing melanoma compared to the general population. While this risk appears to be related to Parkinson's disease itself rather than to any particular medication, periodic dermatological examinations are recommended. Patients should report any suspicious skin lesions to their healthcare provider.
• Hallucinations and psychotic behavior: Dopaminergic therapy, including MAO-B inhibitors, may cause or exacerbate hallucinations and psychotic behavior. This risk is higher in elderly patients. If significant hallucinations occur, dose reduction or discontinuation of AZILECT may be necessary.

Pregnancy and Breastfeeding

There are no adequate and well-controlled studies of rasagiline in pregnant women. Animal reproductive toxicology studies have shown adverse effects at doses significantly higher than the human therapeutic dose, including increased post-implantation loss and decreased pup survival in rats. Given the lack of human data and the potential risks suggested by animal studies, AZILECT should not be used during pregnancy unless the potential benefit to the mother clearly justifies the potential risk to the fetus. Women of childbearing potential should be advised to use effective contraception during treatment.

It is not known whether rasagiline or its metabolites are excreted in human breast milk. Rasagiline has been shown to inhibit prolactin secretion in animal studies, which could potentially affect lactation. Due to the potential for serious adverse reactions in breastfed infants, a decision should be made whether to discontinue breastfeeding or to discontinue AZILECT, taking into account the importance of the medication to the mother. In most clinical situations, breastfeeding should be avoided during AZILECT treatment.

Driving and Operating Machinery

Patients taking AZILECT should exercise caution when driving or operating machinery, particularly during the initial period of treatment. Somnolence (excessive drowsiness) and episodes of sudden onset of sleep have been reported with dopaminergic therapies, including MAO-B inhibitors. While these events are less commonly associated with rasagiline compared to dopamine agonists, patients should be informed of this risk and advised not to drive or engage in potentially hazardous activities until they have gained sufficient experience with AZILECT to assess whether it affects their mental or motor performance.

Use in Elderly Patients

No dose adjustment is required in elderly patients. Parkinson's disease predominantly affects older adults, and the majority of patients in clinical trials of rasagiline were over 60 years of age. The safety and efficacy profile of rasagiline in elderly patients was consistent with that observed in the overall study population. However, elderly patients may be more susceptible to orthostatic hypotension and central nervous system side effects, and should be monitored accordingly.

How Does AZILECT Interact with Other Drugs?

The drug interaction profile of rasagiline is primarily determined by two pharmacological properties: its irreversible inhibition of MAO-B, which affects serotonin and catecholamine metabolism, and its hepatic metabolism via cytochrome P450 1A2 (CYP1A2), which affects its own plasma levels. Understanding these interactions is essential for safe prescribing and patient management.

Unlike older non-selective MAO inhibitors (such as phenelzine and tranylcypromine), rasagiline at the recommended dose of 1 mg daily is selective for MAO-B and does not significantly inhibit MAO-A. This selectivity means that the classic “cheese effect” (hypertensive crisis from tyramine-containing foods) is much less likely with rasagiline than with non-selective MAO inhibitors. However, this selectivity may be lost at higher doses, and caution with tyramine-rich foods remains prudent.

Contraindicated Combinations

Caution-Required Interactions

The interaction between rasagiline and antidepressants deserves particular attention because depression is common in Parkinson's disease, affecting up to 40% of patients. While the prescribing information lists SSRIs and SNRIs as cautionary combinations, clinical experience suggests that many patients can safely use rasagiline with certain SSRIs under careful medical supervision. The incidence of serotonin syndrome with the combination of rasagiline and SSRIs appears to be very low based on post-marketing surveillance data. However, the combination should only be used when the benefits outweigh the risks, and patients should be closely monitored for signs of serotonin syndrome, especially when starting or increasing the dose of either medication.

Regarding pharmacokinetic interactions, rasagiline is primarily metabolized by CYP1A2 in the liver. Strong inhibitors of CYP1A2, such as ciprofloxacin and fluvoxamine, can significantly increase rasagiline plasma concentrations, potentially leading to non-selective MAO inhibition and increased risk of adverse effects. Patients taking AZILECT should avoid ciprofloxacin and should inform their doctor if they are prescribed any fluoroquinolone antibiotic. Conversely, CYP1A2 inducers (such as tobacco smoking and omeprazole) may decrease rasagiline levels, though this is unlikely to be clinically significant given the irreversible nature of MAO-B inhibition.

What Is the Correct Dosage of AZILECT?

AZILECT has a simple and straightforward dosing regimen. The recommended dose is 1 mg (one tablet) taken once daily by mouth. This dose applies to both indications—monotherapy in early Parkinson's disease and adjunct therapy with levodopa in advanced disease. Unlike some other parkinsonian medications that require gradual dose titration, AZILECT can be started at the full therapeutic dose from the first day of treatment. The tablet may be taken with or without food, as food does not significantly affect the overall bioavailability of rasagiline (although it may delay the time to peak plasma concentration by approximately 35 minutes).

Adults

Children and Adolescents

AZILECT is not indicated for use in children and adolescents under 18 years of age. Parkinson's disease is predominantly a condition of older adults, and the safety and efficacy of rasagiline have not been established in the pediatric population. In the extremely rare cases of juvenile-onset Parkinson's disease, treatment decisions should be made by a specialist neurologist with expertise in movement disorders, and other treatment options should be considered.

Elderly Patients

Hepatic Impairment

Renal Impairment

No dose adjustment is required in patients with renal impairment. Rasagiline is primarily metabolized in the liver, and renal excretion plays a minor role in its elimination. Less than 1% of the administered dose is excreted unchanged in the urine. Therefore, even patients with significantly reduced kidney function can take AZILECT at the standard 1 mg daily dose.

Missed Dose

If you forget to take your daily dose of AZILECT, take it as soon as you remember on the same day. However, if it is already close to the time of your next scheduled dose, skip the missed dose and return to your regular dosing schedule. Do not take a double dose to make up for a missed one. Because rasagiline irreversibly inhibits MAO-B, missing a single dose is unlikely to cause a significant resurgence of symptoms, as the enzyme remains inhibited until new MAO-B is synthesized by the body (a process that takes approximately 14 days for complete enzyme regeneration). Nevertheless, consistent daily dosing is recommended for optimal symptom control.

Overdose

There is limited clinical experience with rasagiline overdose. In the event of an overdose, symptoms are likely to reflect exaggerated pharmacological effects, including agitation, irritability, headache, tremor, hypertension, cardiovascular collapse, and potentially serotonin syndrome-like features (if combined with serotonergic agents). At higher doses, rasagiline may lose its selectivity for MAO-B and also inhibit MAO-A, which would increase the risk of hypertensive crisis from tyramine-containing foods consumed after the overdose. Treatment is symptomatic and supportive. There is no specific antidote. Hospitalization and monitoring of vital signs, including blood pressure, are recommended. Contact your local poison control center or emergency medical services immediately if overdose is suspected.

What Are the Side Effects of AZILECT?

Like all medications, AZILECT can cause side effects, although not everyone experiences them. The side effect profile differs somewhat depending on whether rasagiline is used as monotherapy or as adjunct therapy with levodopa, as many of the side effects observed in adjunct therapy are related to enhanced dopaminergic stimulation. The following information is based on data from clinical trials involving over 1,300 patients treated with rasagiline and from post-marketing surveillance experience since the drug's approval.

Clinical trials demonstrated that AZILECT is generally well tolerated. In the TEMPO monotherapy trial, the discontinuation rate due to adverse events was similar between the rasagiline 1 mg group (4.0%) and the placebo group (3.7%). In the PRESTO and LARGO adjunct therapy trials, the discontinuation rates were somewhat higher (approximately 5–7%) but still comparable to placebo. The most commonly reported side effects are listed below by frequency category according to international reporting conventions.

Side Effect Frequency Overview

Dyskinesia is the most commonly reported side effect when AZILECT is used alongside levodopa, occurring in up to 18% of patients in clinical trials compared to approximately 10% in the placebo group. This is a consequence of the enhanced dopaminergic stimulation resulting from the combined action of levodopa and MAO-B inhibition. In most cases, dyskinesia can be managed by reducing the levodopa dose. Your doctor should be informed if dyskinesia becomes troublesome, as dose adjustments can usually provide relief.

Orthostatic hypotension (a fall in blood pressure upon standing) is another notable side effect, occurring more frequently in patients receiving rasagiline plus levodopa. Patients should be advised to change positions slowly, especially when rising from bed in the morning. Adequate fluid intake and avoiding prolonged standing may help minimize this effect. If severe or persistent orthostatic hypotension occurs, medical evaluation is recommended to rule out other contributing factors and to adjust medications as needed.

Hallucinations, while uncommon, are a recognized side effect of dopaminergic therapies in Parkinson's disease. They are more likely to occur in elderly patients, those with cognitive impairment, and those taking multiple dopaminergic medications. If hallucinations develop, a stepwise reduction in dopaminergic medications is usually recommended, and AZILECT may need to be discontinued if hallucinations persist despite other adjustments.

How Should You Store AZILECT?

Proper storage of AZILECT is important to ensure the medication retains its full potency and safety throughout its shelf life. The tablets should be stored at room temperature, not exceeding 25°C (77°F). Keep the tablets in their original blister packaging until the time of use to protect them from moisture and light, as rasagiline may be sensitive to environmental conditions. Do not remove tablets from the blister pack in advance or store them in pill organizers for extended periods without confirming with your pharmacist that this is appropriate.

Store AZILECT in a safe place out of the sight and reach of children and pets. Accidental ingestion by children could cause serious adverse effects due to the potent pharmacological activity of rasagiline. Do not use AZILECT after the expiration date (EXP) stated on the carton and blister strip. The expiration date refers to the last day of that month.

Do not dispose of medications by flushing them down the toilet or throwing them in household waste unless specifically instructed to do so. Ask your pharmacist about proper disposal methods for medications that are no longer needed or have expired. Many pharmacies and local authorities offer medication take-back programs that ensure safe and environmentally responsible disposal.

What Does AZILECT Contain?

Each AZILECT tablet contains rasagiline mesylate equivalent to 1 mg of rasagiline base as the active pharmaceutical ingredient. Rasagiline mesylate is a white to off-white crystalline powder with the chemical name (R)-N-(prop-2-yn-1-yl)-2,3-dihydro-1H-inden-1-amine methanesulfonate. The molecular formula is C₁₂H₁₃NO · CH₄O₃S, and the molecular weight is 267.34 g/mol. The (R)-enantiomer configuration is essential for the pharmacological activity, as the (S)-enantiomer is significantly less potent as a MAO-B inhibitor.

The inactive ingredients (excipients) in AZILECT tablets serve various pharmaceutical purposes:

• Mannitol: A sugar alcohol used as a diluent and filler to give the tablet its appropriate size and weight. It has a pleasant, slightly sweet taste and does not affect blood glucose levels significantly.
• Colloidal anhydrous silica: A flow agent that prevents the powder ingredients from clumping together during the manufacturing process, ensuring uniform tablet content.
• Maize starch: Used as a binder and disintegrant to help the tablet maintain its shape and then break apart appropriately when swallowed.
• Pregelatinized maize starch: A modified starch that serves as both a binder and a disintegrant, contributing to proper tablet dissolution in the gastrointestinal tract.
• Stearic acid: A lubricant that prevents the tablet mixture from sticking to the manufacturing equipment during compression.
• Talc: An additional lubricant and anti-adherent used in the tableting process.

AZILECT tablets are round, flat, white to off-white, with beveled edges and debossed with “GIL” over “1” on one side. The tablets do not contain lactose, gluten, or any animal-derived ingredients. Patients with known sensitivities to maize (corn) starch should inform their healthcare provider, as both maize starch and pregelatinized maize starch are present in the formulation.