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zileuton (zye-loo-ton)

Zyflo CR


Therapeutic: bronchodilators

Pharmacologic: leukotriene antagonists


Long-term control agent in the management of asthma.


Inhibits the enzyme 5-lipoxygenase that catalyzes to formation of leukotrienes. Leukotrienes are components of slow-reacting substance of anaphylaxis (SRSA) and mediate the following: Airway edema, Smooth muscle constriction, Altered cellular activity. Result is decreased inflammatory process that is part of asthma. Therapeutic Effects: ↓ incidence and severity of asthma.

Adverse Reactions/Side Effects

CNS: headache, dizziness, insomnia, malaise, nervousness, somnolence, weakness. EENT: conjunctivitis. CV: chest pain. GI: abdominal pain, constipation, dyspepsia, flatulence, increased liver enzymes, nausea, vomiting. GU: urinary tract infection, vaginitis. Derm: pruritus. MS: arthralgia, myalgia, neck pain. Neuro: hypertonia. Misc: fever, lymphadenopathy.


Examination and Evaluation

  • Assess pulmonary function at rest and during exercise (See Appendices I, J, K) to document effectiveness of medication in controlling bronchoconstriction and asthma attacks.

  • Monitor any chest pain and attempt to determine if pain is drug-induced or caused by cardiovascular dysfunction (e.g., angina that occurs during exercise).

  • Monitor changes in mood and behavior, including nervousness, malaise, unusual drowsiness, and other similar symptoms. Notify the physician if these changes become problematic.

  • Assess any neck, joint, or muscle pain to rule out musculoskeletal pathology; that is, try to determine if pain is drug induced rather than caused by anatomic or biomechanical problems.

  • Assess patient's muscle strength and motor function periodically, and report any increased muscle tone.

  • Assess dizziness and weakness that might affect gait, balance, and other functional activities (See Appendix C). Report balance problems and functional limitations to the physician, and caution the patient and family/caregivers to guard against falls and trauma.


  • When implementing airway clearance techniques or respiratory muscle training, attempt to intervene when the airway is maximally bronchodilated. Peak responses typically occur about 60–90 min after oral administration.

Patient/Client-Related Instruction

  • Advise patient to not exceed the recommended dose or frequency of administration. Contact physician if bronchospasm is not adequately controlled by the current medication regimen or if respiratory symptoms continue to worsen.

  • Instruct patient and family/caregivers to report other troublesome side effects, including severe or prolonged headache, eye inflammation, itching skin, urinary tract infections, vaginal irritation, fever, swollen lymph nodes, or GI problems (nausea, vomiting, diarrhea, constipation, indigestion, flatulence, abdominal pain).


Absorption: Rapidly absorbed following oral administration.

Distribution: Unknown.

Protein Binding: 93%.

Metabolism and Excretion: Mostly metabolized by the liver.

Half-life: 2.5 hr.

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TIME/ACTION PROFILE (improvement in ...

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