Nurses Compass
Drug Guide
Zafirlukast
Classification
Therapeutic: Antiasthmatic, Leukotriene Receptor Antagonist
Pharmacological: Leukotriene receptor antagonist
FDA Approved Indications
- Prevention and chronic treatment of asthma in adults and children 5 years and older
Mechanism of Action
Zafirlukast blocks leukotriene receptors (cysLT1) on airway and inflammatory cells, reducing bronchoconstriction, airway edema, and inflammatory responses in asthma.
Dosage and Administration
Adult: 20 mg orally twice daily, at least 1 hour before or 2 hours after meals.
Pediatric: 20 mg orally twice daily for children 5-11 years old; doses should be administered consistently.
Geriatric: No specific dosage adjustment needed, but renal and hepatic function should be monitored.
Renal Impairment: Use with caution; no specific dose adjustment recommended, but monitoring is advised.
Hepatic Impairment: Use with caution; lower initial doses may be considered, and liver function should be monitored.
Pharmacokinetics
Absorption: Well absorbed with oral administration.
Distribution: Bind to plasma proteins about 99%; volume of distribution approximately 10 L.
Metabolism: Metabolized in the liver via the cytochrome P450 enzyme system, mainly CYP2C9 and CYP3A4.
Excretion: Primarily excreted in feces; minimal urinary excretion.
Half Life: Approximately 10 hours.
Contraindications
- Hypersensitivity to zafirlukast or any component of the formulation.
Precautions
- Use with caution in patients with hepatic impairment, as it may increase drug levels. Not recommended for acute asthma attacks. Monitor liver function periodically.
Adverse Reactions - Common
- Headache (Common)
- Pharyngitis (Common)
- Dizziness (Less common)
Adverse Reactions - Serious
- Churg-Strauss syndrome (eosinophilic granulomatosis with polyangiitis) (Rare)
- Hepatic dysfunction (hepatitis, elevated liver enzymes) (Rare)
- Allergic granulomatous vasculitis (Rare)
Drug-Drug Interactions
- Concurrent use with warfarin may increase bleeding risk. Caution with inhibitors or inducers of CYP450 enzymes.
- drug_food:
- drug_herb:
Drug-Food Interactions
N/ADrug-Herb Interactions
N/ANursing Implications
Assessment: Monitor respiratory status, liver function tests periodically, and for signs of allergic reactions.
Diagnoses:
- Impaired airway clearance related to bronchospasm.
- Risk for hepatic injury.
Implementation: Administer as prescribed, preferably on an empty stomach. Educate patient on signs of liver dysfunction or allergic reactions.
Evaluation: Assess for reduction in asthma symptoms, decreased use of rescue inhalers, and absence of adverse effects.
Patient/Family Teaching
- Take medication exactly as prescribed, even when asymptomatic.
- Report any signs of liver problems (jaundice, dark urine) or allergic reactions.
- Carry medical identification indicating use of zafirlukast.
Special Considerations
Black Box Warnings:
- None currently
Genetic Factors: No specific genetic testing required.
Lab Test Interference: May elevate serum levels of liver enzymes, which can interfere with diagnoses of hepatic conditions.
Overdose Management
Signs/Symptoms: Nausea, vomiting, abdominal pain, somnolence.
Treatment: Supportive care; no specific antidote available. Consider activated charcoal if ingestion was recent.
Storage and Handling
Storage: Store at room temperature, 20-25°C (68-77°F).
Stability: Stable under recommended storage conditions.