zafirlukast
[zah-fir´loo-kast]zafirlukast
Pharmacologic class: Leukotriene receptor antagonist
Therapeutic class: Antiasthmatic, bronchodilator
Pregnancy risk category B
Action
Antagonizes activity of three leukotrienes at specific receptor sites in airway smooth muscle, inhibiting inflammation
Availability
Tablets (coated): 10 mg, 20 mg
Indications and dosages
➣ Prophylaxis and long-term treatment of asthma
Adults and children ages 12 and older: 20 mg P.O. b.i.d.
Children ages 5 to 11: 10 mg P.O. b.i.d.
Off-label uses
• Exercise-induced bronchospasm
• Chronic urticaria
Contraindications
• Hypersensitivity to drug or its components
• Hepatic impairment, including hepatic cirrhosis
Precautions
Use cautiously in:
• acute asthma attacks
• concurrent use of warfarin
• patients older than age 55
• pregnant patients
• breastfeeding patients (use not recommended)
• children younger than age 5 (safety not established).
Administration
• Give at least 1 hour before or 2 hours after a meal.
Adverse reactions
CNS: headache, dizziness, asthenia, insomnia, depression (especially in children and adolescents)
GI: nausea, vomiting, diarrhea, abdominal pain, dyspepsia
Hepatic: hepatic dysfunction including liver failure and death (rare)
Musculoskeletal: joint or back pain, myalgia
Other: fever, infection, pain
Interactions
Drug-drug. Aspirin: increased zafirlukast blood level
Erythromycin, theophylline: decreased zafirlukast blood level
Warfarin: increased warfarin effects, greater risk of bleeding
Drug-food. Any food: decreased rate and extent of zafirlukast absorption
Patient monitoring
• Assess patient's respiratory status to help evaluate drug efficacy.
☞ Monitor liver function tests closely; watch for signs and symptoms of liver dysfunction.
Patient teaching
• Tell patient to take at least 1 hour before or 2 hours after a meal.
• Advise patient to take exactly as prescribed, even if he is symptom-free.
☞ Tell patient to immediately report asthma attack. Advise him not to use drug for rapid relief of bronchospasm.
• Instruct patient to continue taking other asthma drugs unless prescriber directs otherwise.
☞ Instruct patient to immediately report signs and symptoms of liver dysfunction (nausea, anorexia, fatigue, lethargy, pruritus, jaundice, flulike symptoms, or right upper quadrant abdominal pain).
• Instruct patient or caregiver to report insomnia or depression.
• Instruct female patient to consult prescriber if she plans to breastfeed.
• As appropriate, review all other significant adverse reactions and interactions, especially those related to the drugs and foods mentioned above.