Overview
11 DESCRIPTION Zileuton is an orally active inhibitor of 5-lipoxygenase, the enzyme that catalyzes the formation of leukotrienes from arachidonic acid. Zileuton has the chemical name (±)-1-(1-Benzo[b]thien-2-ylethyl)-1-hydroxyurea and the following chemical structure: Zileuton has the molecular formula C 11 H 12 N 2 O 2 S and a molecular weight of 236.29.
Mechanism of Action
12 CLINICAL PHARMACOLOGY 12.1 Mechanism of Action Zileuton is an inhibitor of 5-lipoxygenase and thus inhibits leukotriene (LTB 4 , LTC 4 , LTD 4 and LTE 4 ) formation. Both the R(+) and S(-) enantiomers are pharmacologically active as 5-lipoxygenase inhibitors in in vitro and in vivo systems. Leukotrienes are substances that induce numerous biological effects including augmentation of neutrophil and eosinophil migration, neutrophil and monocyte aggregation, leukocyte adhesion, increased capillary permeability, and smooth muscle contraction. These effects contribute to inflammation, edema, mucus secretion, and bronchoconstriction in the airways of asthmatic patients.
Indications
- 1 INDICATIONS AND USAGE 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 tablet can be continued during acute exacerbations of asthma. Zileuton extended-release tablets are a leukotriene synthesis inhibitor indicated for the prophylaxis and chronic treatment of asthma in adults and children 12 years of age and older.
Common Doses
- 600 mg
- 2400 mg
Dosage
2 DOSAGE AND ADMINISTRATION 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...
Contraindications
- 4 CONTRAINDICATIONS The use of zileuton extended-release tablets are 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 (≥3xULN) [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.). • Active liver disease or persistent hepatic function enzyme elevations ≥3 times the upper limit of normal. ( 4 , 5.
Side Effects
- 6 ADVERSE REACTIONS 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. Most common adverse reactions (≥5%) included: sinusitis, nausea, and pharyngolaryngeal pain. ( 6.1 ) To report SUSPECTED ADVERSE REACTIONS, contact Annora Pharma Private Limited at 1-866-495-1995 or FDA at 1-800-FDA-1088 or www.fda.gov/medwatch 6.
Interactions
- 7 DRUG INTERACTIONS The following study results were obtained using zileuton immediate-release tablets but the conclusions also apply to zileuton extended-release tablets. • Zileuton increases theophylline levels. Reduce theophylline dose and monitor levels. ( 7.1 ) • Zileuton increases warfarin levels. Monitor prothrombin time and adjust warfarin dose accordingly. ( 7.2 ) • Zileuton increases propranolol levels and beta-blocker activity. Monitor appropriately. ( 7.3 ) 7.