ZILEUTON- zileuton tablet, multilayer, extended release
Par Pharmaceutical, Inc.


Zileuton extended-release tablets are indicated for the prophylaxis and chronic treatment of asthma in adults and children 12 years of age and older.

Zileuton extended-release tablets are not indicated for use in the reversal of bronchospasm in acute asthma attacks. Therapy with zileuton extended-release tablets can be continued during acute exacerbations of asthma.


The recommended dosage of Zileuton extended-release tablets for the treatment of patients with asthma is two 600 mg extended-release tablets twice daily, within one hour after morning and evening meals, for a total daily dose of 2400 mg. Tablets should not be chewed, cut or crushed. If a dose is missed, the patient should take the next dose at the scheduled time and not double the dose. Assess hepatic function enzymes prior to initiation of Zileuton extended-release tablets and periodically during treatment [see Contraindications (4),Warnings and Precautions (5), and Use in Specific Populations (8.7)].


  • Extended-release tablets, 600 mg.


The use of Zileuton extended-release tablets is contraindicated in patients with:

  • Active liver disease or persistent hepatic function enzyme elevations greater than or equal to 3 times the upper limit of normal (≥3×ULN) [see Warnings and Precautions (5),and Use in Specific Populations (8.7)].
  • A history of allergic reaction to zileuton or any of the ingredients of Zileuton extended-release tablets (e.g., rash, eosinophilia, etc.).


5.1 Hepatotoxicity

Elevations of one or more hepatic function enzymes and bilirubin may occur during Zileuton extended-release tablets therapy. These laboratory abnormalities may progress to clinically significant liver injury, remain unchanged, or resolve with continued treatment, usually within three weeks. The ALT (SGPT) test is considered the most sensitive indicator of liver injury for Zileuton extended-release tablets.

Assess hepatic function enzymes prior to initiation of, and during therapy with, Zileuton extended-release tablets. Assess serum ALT before treatment begins, once a month for the first 3 months, every 2-3 months for the remainder of the first year, and periodically thereafter for patients receiving long-term Zileuton extended-release tablets therapy. 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 ≥5×ULN occur, discontinue Zileuton extended-release tablets and follow hepatic function enzymes until normal.

In controlled and open-label clinical studies involving more than 5000 patients treated with zileuton immediate-release tablets, the overall rate of ALT elevation ≥3×ULN was 3.2%. In these trials, one patient developed symptomatic hepatitis with jaundice, which resolved upon discontinuation of therapy. An additional 3 patients with transaminase elevations developed mild hyperbilirubinemia that was less than 3×ULN. There was no evidence of hypersensitivity or other alternative etiologies for these findings.

Since treatment with Zileuton extended-release tablets may result in increased hepatic function enzymes and liver injury, Zileuton extended-release tablets should be used with caution in patients who consume substantial quantities of alcohol and/or have a past history of liver disease.

5.2 Neuropsychiatric Events

Neuropsychiatric events have been reported in adult and adolescent patients taking zileuton, the active ingredient in Zileuton extended-release tablets and zileuton immediate-release tablets. Post-marketing reports with zileuton include sleep disorders and behavior changes. The clinical details of some post-marketing reports involving zileuton appear consistent with a drug-induced effect. Patients and prescribers should be alert for neuropsychiatric events. Patients should be instructed to notify their prescriber if these changes occur. Prescribers should carefully evaluate the risks and benefits of continuing treatment with Zileuton extended-release tablets if such events occur [see Adverse Reactions (6.3)].


Hepatotoxicity: Elevations of one or more hepatic function enzymes and bilirubin may occur during Zileuton extended-release tablets therapy [see Warnings and Precautions (5)].

The most commonly occurring adverse reactions (≥5%) with Zileuton extended-release tablets are sinusitis, nausea, and pharyngolaryngeal pain.

6.1 Short-Term Clinical Studies Experience

The safety data described below reflect exposure to Zileuton extended-release tablets in 199 patients for 12 weeks duration. In a 12-week, randomized, double-blind, placebo-controlled trial in adults and adolescents 12 years of age and older with asthma, patients received Zileuton extended-release tablets two 600 mg tablets (n=199) or placebo (n=198) twice daily by mouth. Eighty-three percent of patients were white, 48% were male, and the mean age was 34 years.

Because clinical studies are conducted under widely varying conditions, adverse reaction rates observed in the clinical studies of a drug cannot be directly compared to rates in the clinical studies of another drug and may not reflect the rates observed in practice.

The most commonly reported adverse reactions (occurring at a frequency of ≥5%) in Zileuton extended-release tablets-treated patients and at a frequency greater than placebo-treated patients are reflected in Table 1.

Table 1.

Adverse Reactions with ≥5% Incidence in a 12‑Week Placebo-Controlled Trial in Patients with Asthma.

Adverse Reaction

Zileuton Extended-Release Tablets

600 mg 2 Tablets Twice Daily


n (%)


2 Tablets Twice Daily


n (%)


13 (6.5)

8 (4.0)


10 (5.0)

3 (1.5)

Pharyngolaryngeal pain

10 (5.0)

8 (4.0)

Less common adverse reactions occurring at a frequency ≥1% and more often in the zileuton extended-release tablets group than in the placebo group included gastrointestinal disorders (upper abdominal pain, diarrhea, dyspepsia, vomiting), rash, hypersensitivity, and hepatotoxicity.

There were no differences in the incidence of adverse reactions based upon gender. The clinical trials did not include sufficient numbers of patients <18 years of age or non-Caucasians to determine whether there is any difference in adverse reactions based upon age or race.

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