Singulair 4 mg Tablets

Brand Name

Singulair is the widely recognized brand name under which this medication is distributed, highly regarded in medical practice for its role in managing respiratory conditions. It has become a trusted option for clinicians addressing specific allergic and asthmatic disorders.

International Nonproprietary Name (INN)

The active substance in this drug is identified by its International Nonproprietary Name (INN) as montelukast. This leukotriene receptor antagonist is meticulously designed to deliver targeted relief within the respiratory system.

Forms of Release

Singulair is available in several formulations to accommodate varying patient needs and age groups. These include film-coated tablets in a 10 mg strength for adults and adolescents, chewable tablets in 4 mg and 5 mg doses for children, and oral granules at 4 mg per packet for infants and young children unable to swallow tablets. Each form is crafted to ensure consistent delivery of montelukast, providing flexibility in administration tailored to individual therapeutic requirements.

Composition

The primary active ingredient in Singulair is montelukast sodium, which drives its pharmacological effects. Alongside this core component, the medication incorporates various inactive substances to enhance stability and usability. Film-coated tablets contain microcrystalline cellulose, lactose monohydrate, and magnesium stearate, with a coating of hypromellose, titanium dioxide, and iron oxide for appearance and protection. Chewable tablets include mannitol, aspartame, and cherry flavoring, while oral granules feature mannitol and hydroxypropyl cellulose in a powder base. These auxiliary elements work together to maintain the drug’s integrity and facilitate its administration across its diverse forms.

Pharmacologic Properties

Pharmacodynamics

This medication exerts its influence by modulating inflammatory pathways in the respiratory tract. Montelukast operates by selectively blocking cysteinyl leukotriene receptors (CysLT1), which are activated by leukotrienes—lipid mediators released during allergic and inflammatory responses. By preventing leukotriene binding, it reduces bronchoconstriction, mucus secretion, and airway inflammation, key features of asthma and allergic rhinitis. This action alleviates wheezing, shortness of breath, and nasal congestion, offering sustained symptom control without directly affecting other inflammatory cascades like prostaglandins. Its targeted mechanism provides relief in allergic and asthmatic states, enhancing respiratory function effectively.

Pharmacokinetics

The pharmacokinetic profile of Singulair outlines how montelukast is processed within the body. After oral administration, it is rapidly absorbed from the gastrointestinal tract, reaching peak plasma concentrations within 3 to 4 hours for tablets, 2 to 2.5 hours for chewables, and 2 hours for granules, with bioavailability averaging 64% for tablets (reduced to 63% with food) and 73% for chewables. It is 99% bound to plasma proteins, primarily albumin, with a volume of distribution of 8–11 liters, indicating limited tissue penetration. Metabolism occurs extensively in the liver via cytochrome P450 2C8 and 3A4, producing minimally active metabolites, with excretion predominantly through bile (86%) and a small fraction via urine. Its half-life ranges from 2.7 to 5.5 hours, stable across most conditions, requiring no routine adjustment in mild organ impairment.

Indications for Use

This medication is prescribed for conditions involving allergic or inflammatory respiratory responses, capitalizing on its ability to mitigate these symptoms across specific disorders.

Diseases and Conditions

Singulair is indicated for the prophylaxis and chronic treatment of asthma in adults and children aged 12 months and older, reducing daytime and nighttime symptoms, including exercise-induced bronchoconstriction. It is also approved for the relief of seasonal allergic rhinitis in patients 2 years and older, and perennial allergic rhinitis in those 6 months and older, alleviating nasal congestion, sneezing, and itching. Its targeted action makes it a valuable option for these respiratory and allergic challenges, enhancing quality of life.

Contraindications

While effective for many, certain conditions preclude the use of this medication due to potential risks, necessitating careful evaluation before therapy begins.

Conditions Prohibiting Use

Singulair is contraindicated in patients with known hypersensitivity to montelukast or any formulation components, as reactions could range from mild skin irritation to severe anaphylaxis. It is not indicated for acute asthma attacks, requiring alternative rescue therapies like bronchodilators in such cases. No other absolute contraindications are widely established, though caution is advised in phenylketonuria patients using chewables due to aspartame content. These restrictions ensure safety and appropriate use across patient populations.

Method of Administration and Dosage

How to Take

This medication is administered orally, with specifics varying by form. Film-coated tablets are swallowed whole with water, chewable tablets are chewed before swallowing, and oral granules can be taken directly, mixed with a spoonful of soft food (e.g., applesauce), or dissolved in formula or breast milk for infants, followed by immediate ingestion. It is typically taken in the evening, as asthma symptoms often worsen at night, and can be taken with or without food, though consistency aids efficacy. Patients should adhere to prescribed methods to maintain steady therapeutic levels.

Dosages for Adults and Children

Dosing is tailored to age and indication. For asthma or allergic rhinitis in adults and adolescents 15 years and older, Singulair is 10 mg once daily. Children aged 6–14 years receive 5 mg chewable tablets once daily, while those 2–5 years use 4 mg chewables or granules once daily. Infants 12–23 months with asthma or 6–23 months with perennial rhinitis take 4 mg granules once daily. Dosing remains consistent across indications, with no escalation beyond these levels, ensuring simplicity and safety across age groups.

Dose Adjustment in Specific Conditions

Adjustments are rarely needed in renal or hepatic impairment. In mild to moderate renal dysfunction (creatinine clearance 30–80 mL/min), no change is required, with severe cases (below 30 mL/min) lacking data but typically safe at standard doses due to minimal renal excretion. Mild to moderate hepatic impairment (Child-Pugh A or B) requires no adjustment, though severe cases (Child-Pugh C) suggest caution without specific reductions, guided by monitoring. Elderly patients use standard doses, with oversight for tolerability, maintaining efficacy across conditions.

Side Effects

This medication can elicit a variety of adverse reactions, from mild to notable, and patients should be informed to facilitate prompt recognition and management.

Possible Adverse Reactions

Common effects include upper respiratory infections, headache, or fever, often mild and transient. Gastrointestinal upset—abdominal pain or diarrhea—may occur, particularly in children, while fatigue or drowsiness affects some. Behavioral changes, such as agitation, anxiety, or rare suicidal ideation, have been reported, warranting vigilance, especially in younger patients. Skin rashes, sinusitis, or otitis media are less frequent, with rare instances of hepatic enzyme elevations or hypersensitivity reactions (e.g., eosinophilia). Regular follow-ups help address these potential outcomes effectively.

Overdose

Symptoms of Overdose

Excessive intake of Singulair can lead to noticeable symptoms requiring attention. These include thirst, abdominal pain, or vomiting from gastrointestinal irritation, alongside drowsiness or headache from systemic effects. Hyperactivity or agitation may occur, particularly in children, while severe cases could involve respiratory distress or confusion, though rare. Symptoms are generally mild with doses up to 1000 mg, but prompt recognition is key to ensure safety.

First Aid Measures

In an overdose scenario, swift action is advised. If the patient is alert and ingestion was recent, contact emergency services or poison control without inducing vomiting unless instructed. Maintain airway and vital signs while awaiting help. In medical settings, supportive care—hydration, symptom monitoring—is typically sufficient, with activated charcoal considered within an hour of ingestion if significant. Dialysis is ineffective due to high protein binding, but observation ensures resolution.

Drug Interactions

Effects on Other Medications

This medication has a low interaction profile due to minimal metabolic interference. It does not significantly affect drugs metabolized by CYP2C9, 3A4, or 1A2, but inducers like phenobarbital or rifampin may reduce its levels by 40%, potentially lowering efficacy, though adjustments are rare. Gemfibrozil may slightly increase its concentrations, with negligible clinical impact. No notable effects occur with corticosteroids or antihistamines, ensuring safe co-use in allergy or asthma management.

Compatibility with Alcohol and Food

Alcohol poses no significant interaction with Singulair, though moderation is advised to avoid exacerbating respiratory conditions. Food slightly reduces tablet bioavailability, but all forms can be taken with or without meals, with consistency aiding steady levels. No dietary restrictions apply, supporting flexible use.

Special Precautions

Use During Pregnancy and Breastfeeding

This medication is Category B, with no evidence of fetal harm in animal studies, used in pregnancy if benefits outweigh risks, with human data suggesting safety. Montelukast enters breast milk in trace amounts; breastfeeding is generally safe, with monitoring for infant drowsiness, though alternatives may be considered.

Impact on Driving and Operating Machinery

Singulair may cause drowsiness or dizziness in some, particularly early in use. Patients should avoid driving or machinery until they assess its effects, ensuring safety in daily activities.

Considerations for Elderly and Pediatric Patients

In elderly patients, standard 10 mg dosing is safe, with no adjustments needed unless organ function declines significantly, monitored for tolerability. In children 6 months and older, age-specific doses (4–5 mg) are well-established for asthma and rhinitis, with oversight for behavioral effects, ensuring tailored care across ages.