zafirlukast

zafirlukast

(zah fur' luh kast)

Accolate

Pregnancy Category B

Drug classes

Antasthmatic

Leukotriene receptor antagonist

Therapeutic actions

Selectively and competitively blocks receptor for leukotriene D₄ and E₄, components of SRS-A, thus blocking airway edema, smooth muscle constriction, and cellular activity associated with inflammatory process that contribute to signs and symptoms of asthma.

Indications

·        Prophylaxis and long-term treatment of bronchial asthma in adults and children > 5 yr

·        Unlabeled use: Chronic urticaria

Contraindications and cautions

·        Contraindicated with hypersensitivity to zafirlukast or any of its components; acute asthma attacks; status asthmaticus.

·        Use cautiously in patients who previously required corticosteroid therapy to control asthma; with hepatic or renal impairment; as oral steroid use is decreased; pregnancy; lactation.

Available forms

Tablet—10, 20 mg

Dosages

ADULTS AND CHILDREN > 12 YR

20 mg PO bid on an empty stomach.

PEDIATRIC PATIENTS 5–11 YR

10 mg PO bid on an empty stomach.

Pharmacokinetics

Route	Onset	Peak
Oral	Rapid	3 hr

Metabolism: Hepatic; T_1/2: 10 hr

Distribution: Crosses placenta; enters breast milk

Excretion: Feces, urine

Adverse effects

·        CNS: Headache, dizziness, myalgia

·        GI: Nausea, diarrhea, abdominal pain, vomiting, liver enzyme elevation

·        Other: Generalized pain, fever, accidental injury, infection; Churg-Strauss syndrome (eosinophilia, vasculitic rash, pulmonary and cardiac complications) when oral steroid dose is reduced

Interactions

Drug-drug

·        Increased risk of bleeding with warfarin; these patients should have PT done regularly and warfarin dose decreased accordingly

·        Potential for increased effects and toxicity of calcium channel-blockers, cyclosporine

·        Decreased effectiveness with erythromycin, theophylline

·        Possible severe reaction when oral steroid dose is reduced while on zafirlukast; monitor patients very closely

Drug-food

·        Bioavailability decreased markedly by presence of food; administer at least 1 hr before or 2 hr after meals

Nursing considerations

Assessment

·        History: Hypersensitivity to zafirlukast; impaired renal or hepatic function; pregnancy, lactation; acute asthma or bronchospasm

·        Physical: T; orientation, reflexes; R, adventitious sounds; GI evaluation; LFTs, renal function tests

Interventions

·        Administer on an empty stomach 1 hr before or 2 hr after meals.

·        Ensure that drug is taken continually for optimal effect.

·        WARNING: Do not administer for acute asthma attack or acute bronchospasm.

Teaching points

·        Take this drug on an empty stomach, 1 hour before or 2 hours after meals.

·        Take this drug regularly as prescribed; do not stop taking it during symptom-free periods; do not stop taking it without consulting your health care provider.

·        Do not take this drug for acute asthma attack or acute bronchospasm; this drug is not a bronchodilator; routine emergency procedures should be followed during acute attacks.

·        Avoid use of over-the-counter medications while using this drug; many of them contain products that can interfere with drug or cause serious side effects. If you feel that you need one of these products, consult your health care provider.

·        You may experience these side effects: Dizziness (use caution when driving or performing activities that require alertness); nausea, vomiting (eat frequent small meals); headache (analgesics may be helpful).

·        Report fever, acute asthma attacks, severe headache.

Adverse effects in Italic are most common; those in Bold are life-threatening.