Medication Name and Formulation

Singulair, also known by its generic name montelukast, is available in tablet, chewable tablet, and granule forms. The standard tablet is typically 10 mg, whereas chewable tablets come in 4 mg and 5 mg dosages. The granules are usually provided in 4 mg packets.

Active Ingredients

Singulair’s active ingredient is montelukast sodium. Each tablet, chewable tablet, or packet of granules contains a specific dosage of montelukast sodium. The inactive ingredients vary depending on the form of the medication but can include components used for tablet binding, flavoring in chewable forms, and stabilization in granules.

Mechanism of Action

Montelukast works as a leukotriene receptor antagonist. By blocking specific receptors in the lungs, it prevents the action of leukotrienes, which are substances in the body that cause asthma and allergic rhinitis symptoms. As a result, inflammation and bronchoconstriction are reduced, easing breathing and other associated symptoms.

Indications and Usage

Singulair is primarily indicated for the prevention and chronic treatment of asthma in adults and pediatric patients. It is also approved for the relief of symptoms of seasonal allergic rhinitis and perennial allergic rhinitis. Additionally, Singulair can be used for the prevention of exercise-induced bronchoconstriction.

Dosage and Administration

The dosage of Singulair varies based on the condition being treated and the age of the patient. For adults and adolescents aged 15 and over, the standard dosage for asthma and allergic rhinitis is 10 mg once daily in the evening. Pediatric patients aged 6 to 14 years may take one 5 mg chewable tablet daily. For children aged 2 to 5 years, the recommended dosage is one 4 mg chewable tablet or one packet of 4 mg granules daily.

Administration Guidelines

Singulair should be taken at least 2 hours before exercise for exercise-induced bronchoconstriction. The granules can be administered either directly in the mouth or mixed with a spoonful of cold or room temperature food such as applesauce, carrots, rice, or ice cream. Chewable tablets should be chewed thoroughly before swallowing. Standard tablets should be swallowed whole with water.

Storage Conditions

Singulair should be stored at room temperature, between 20°C and 25°C (68°F to 77°F). The medication should be kept away from direct sunlight and moisture. The granule packets should be used within 15 minutes of opening.

Pharmacokinetics

Montelukast is rapidly absorbed following oral administration with peak plasma concentrations occurring within 3 to 4 hours. The bioavailability is approximately 64% following a 10 mg dose. The drug is extensively metabolized in the liver via the cytochrome P450 enzyme system, specifically CYP3A4 and CYP2C9. It is primarily excreted in bile, with less than 0.2% excreted in the urine.

Interactions with Other Drugs

Montelukast has been shown to interact with several other medications. Drugs such as phenobarbital and rifampin that induce the cytochrome P450 3A4 pathway may decrease the concentration of montelukast, potentially reducing its efficacy. Montelukast does not significantly affect the pharmacokinetics of contraceptives, warfarin, digoxin, theophylline, or prednisone.

Side Effects and Adverse Reactions

The common side effects of Singulair include headache, stomach pain, heartburn, and, in some cases, tiredness. More serious adverse reactions can include neuropsychiatric events such as agitation, aggressive behavior, depression, and hallucinations. Liver enzyme alterations and allergic reactions like rash or swelling can also occur. Rarely, Churg-Strauss syndrome, a condition involving blood vessel inflammation, has been associated with the use of Singulair.

Contraindications

Singulair is contraindicated in patients with a known hypersensitivity to montelukast or any of its ingredients. It is not intended for acute asthma attacks or asthmatic status conditions. It should be used cautiously in patients with a history of psychiatric disorders due to potential neuropsychiatric effects.

Special Populations Considerations

In elderly patients, no dosage adjustment is necessary based on age alone. However, hepatic impairment can alter the metabolism of montelukast; thus, caution is advised in such patients. Pregnant and breastfeeding women should use Singulair only if clearly needed, as the drug crosses the placenta and is excreted in breast milk.

Monitoring Recommendations

Patients on long-term montelukast therapy should have regular monitoring for liver function tests due to potential hepatotoxicity. Monitoring for neuropsychiatric symptoms is also advised, particularly during the initiation of therapy and during dosage adjustments. Regular assessment of asthma control is essential for adjusting the Singulair dosage or adding additional therapy.

Dosage Form Differences

The choice between the tablet, chewable tablet, and granules depends largely on patient age, ease of administration, and specific patient needs. Chewable tablets are typically preferred for younger children who may have difficulty swallowing tablets. Granules offer a pediatric-friendly option for very young children who may not tolerate solid forms.

Titration and Transition

When transitioning patients from a different leukotriene receptor antagonist to Singulair, it’s crucial to account for the existing therapeutic levels of the prior medication. Overlapping therapy or titration may be necessary to ensure disease control without interruption. Titration should be done cautiously and based on clinical response.

Patient Counseling Points

Patients should be instructed to take Singulair consistently, even during symptom-free periods, and not to discontinue abruptly without consulting a healthcare provider. Emphasize the importance of adherence to daily dosage and regular asthma management practices. They should be aware of potential side effects and the need to report any unusual symptoms promptly.