ZILEUTON
(zi-leu'ton)
Zyflo
Classifications: bronchodilator (respiratory smooth muscle relaxant); leukotriene receptor antagonist
Prototype: Zafirlukast
Pregnancy Category: C
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600 mg tablets
Inhibits 5-lipoxygenase, the enzyme needed to start the conversion of arachidonic acid to leukotrienes. 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.
Zileuton helps to prevent the signs and symptoms of asthma including airway edema, smooth muscle constriction, and altered
cellular activity due to inflammation.
Prophylaxis and chronic treatment of asthma in adults and children >12 y.
Hypersensitivity to zileuton or zafirlukast, active liver disease, lactation, pregnancy (category C).
Hepatic insufficiency. Safety and effectiveness in children >12 y are not established.
Asthma
Adult/Child: PO >12 y, 600 mg q.i.d.
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Oral
- Give at meals and bedtime.
- Store at room temperature, 15°–30° C (59°–86° F); protect from light.
Body as a Whole: Pain, asthenia, myalgia, arthralgia, fever, malaise, neck pain/rigidity. CNS:
Headache, dizziness, insomnia, nervousness, somnolence. CV: Chest pain. GI: Abdominal pain, dyspepsia, nausea, constipation, flatulence, vomiting, elevated liver function tests, asymptomatic hepatitis. Skin: Pruritus. Other: Conjunctivitis, hypertonia, lymphadenopathy, vaginitis, UTI, leukopenia.
Drug: May double theophylline levels and increase toxicity. Increases hypoprothrombinemic effects of warfarin. May increase levels of beta blockers (especially propranolol), leading to hypotension and bradycardia.
Absorption: Rapidly absorbed from GI tract. Peak: 1.7 h. Duration: 5–8 h. Distribution: 93% protein bound; secreted in the breast milk of rats. Metabolism: Metabolized in liver primarily via glucuronide conjugation. Elimination: Excreted primarily in urine (94%). Half-Life: 2.5 h.
Assessment & Drug Effects
- Assess respiratory status and airway function regularly.
- Lab tests: Periodic CBC and routine blood chemistry; monthly liver function tests for 3 mo, then every 2–3 mo for rest
of first year, then periodically.
- Instructions for CONCURRENT THERAPIES: Reduce theophylline dose and closely monitor theophylline levels; closely monitor PT and INR with warfarin therapy; closely
monitor phenytoin level with phenytoin therapy; closely monitor HR and BP for excessive beta blockade with propranolol therapy.
Patient & Family Education
- Take medication regularly even during symptom-free periods.
- Drug is not intended to treat acute episodes of asthma.
- Report to physician promptly S&S of hepatic toxicity (see Appendix F) or flu-like symptoms. Follow-up lab work is very important.
- Notify physician if condition worsens while using prescribed doses of all antiasthmatic medications.
- Do not breast feed while taking this drug.
1%)
Canadian drug name; 
Prototype drug