ZYFLO CR (zileuton) is indicated for the prophylaxis and chronic treatment of asthma in adults and children 12 years of age and older. ZYFLO CR is not indicated for use in the reversal of bronchospasm in acute asthma attacks. Therapy with ZYFLO CR can be continued during acute exacerbations of asthma.
Important Safety Information
ZYFLO CR is contraindicated in patients with active liver disease or persistent hepatic function enzyme elevations ≥3 times the upper limit of normal or a history of allergic reactions to zileuton or any of the other ingredients.
Elevations of one or more hepatic function enzymes and bilirubin may occur during ZYFLO CR therapy.
Assess hepatic function enzymes prior to initiation of ZYFLO CR, monthly for the first 3 months, every 2-3 months for the remainder of the first year, and periodically thereafter.
If clinical signs and/or symptoms of liver dysfunction develop (e.g., right upper quadrant pain, nausea, fatigue, lethargy, pruritus, jaundice, or “flu-like” symptoms) or transaminase elevations ≥5xULN occur, discontinue ZYFLO CR and follow hepatic function enzymes until normal.
Neuropsychiatric events, including sleeping disorders and behavioral changes, may occur with ZYFLO CR.
The active ingredient in ZYFLO CR increases theophylline, warfarin, and propranolol levels. Dose adjustment of these other drugs and patient monitoring may be required.
ZYFLO CR should be used with caution in patients who consume substantial quantities of alcohol and/or have a history of liver disease.
In a long-term clinical trial (n=926), the incidence of ALT elevations (≥3xULN) was 1.8% in the ZYFLO CR group, compared to 0.7% in the placebo group.
Most common adverse reactions (≥5%) included: sinusitis, nausea, and pharyngolaryngeal pain.
You are encouraged to report negative side effects of prescription drugs to the FDA. Visit www.fda.gov/medwatch or call 1-800-FDA-1088.