MONTELUKAST

MONTELUKAST (mon-te-lu'cast) Singulair Classifications: bronchodilator (respiratory smooth muscle relaxant); leukotriene receptor antagonist; Therapeutic: bronchodilator; leukotriene receptor antagonist Prototype: Zafirlukast Pregnancy Category: B

Availability

5 mg, 10 mg tablets; 4 mg chewable tablets; 4 mg oral granules

Action

Selective receptor antagonist of leukotriene D₄, thus inhibiting bronchoconstriction. Leukotrienes are considered more important than prostaglandins as inflammatory agents; they induce bronchoconstriction and mucus production. Elevated sputum and blood levels of leukotrienes have been documented during acute asthma attacks.

Therapeutic Effect

Controls asthmatic attacks by inhibiting leukotriene release as well as inflammatory action associated with the attack. Indicated by improved pulmonary functions and better controlled asthmatic symptoms.

Uses

Prophylaxis and chronic treatment of asthma or allergic rhinitis; exercise-induced bronchoconstriction (EIB).

Contraindications

Hypersensitivity to montelukast; acute asthma attacks; bronchoconstriction due to asthma or NSAIDs; status asthmaticus; children <6 mo; lactation.

Cautious Use

Hypersensitivity to other leukotriene receptor antagonists (e.g., zafirlukast, zileuton); severe liver disease; jaundice, PKU; severe asthma; pregnancy (category B).

Route & Dosage

Asthma Adult: PO 10 mg q.d. in evening Child: PO 12 mo–5 y, 4 mg q.d. in evening; 6–14 y, 5 mg chewable tablet q.d. in evening EIB Adult/Adolescent (>15 y): PO 10 mg 2 h before exercise (not more than 1 per day)

Administration

Oral

• Give in the evening for maximum effectiveness.
• Ensure chewable tablets for children are not swallowed whole.
• Store at 15°–30° C (59°–86° F) in a tightly closed container and protect from light.

Adverse Effects (≥1%)

Body as a Whole: Asthenia, fever, trauma. CNS: Dizziness, headache. GI: Abdominal pain, dyspepsia, gastroenteritis, dental pain, abnormal liver function tests (ALT, AST), diarrhea, nausea. Respiratory: Nasal congestion, cough, influenza, laryngitis, pharyngitis, sinusitis. Skin: Rash. Urogenital: Pyuria.

Pharmacokinetics

Absorption: Rapidly absorbed from GI tract, bioavailability 64%. Peak: 3–4 h for oral tablet, 2–2.5 h for chewable tablet. Distribution: >99% protein bound. Metabolism: Extensively metabolized by cytochromes P450 3A4 and 2C9. Elimination: In feces. Half-Life: 2.7–5.5 h.

Nursing Implications

Assessment & Drug Effects

• Monitor effectiveness carefully when used in combination with phenobarbital or other potent cytochrome P450 enzyme inducers.
• Lab test: Periodic liver function tests.

Patient & Family Education

• Do not use for reversal of an acute asthmatic attack.
• Inform physician if short-acting inhaled bronchodilators are needed more often than usual with montelukast.
• Use chewable tablets (contain phenylalanine) with caution with PKU.

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Common adverse effects in italic, life-threatening effects underlined; generic names in bold; classifications in SMALL CAPS; Canadian drug name; Prototype drug