Zileuton

drugbox
IUPAC_name = 1-(1-benzothiophen-2-ylethyl)-1-hydroxy-urea

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width = 213
CAS_number = 111406-87-2
ATC_prefix =
ATC_suffix =
ATC_supplemental =
PubChem = 60490
DrugBank = APRD00265
C = 11 | H = 12 | N = 2 | O = 2 | S = 1
molecular_weight = 236.291 g/mol
bioavailability = Not yet established
protein_bound = 93%
metabolism = Hepatic (CYP1A2, CYP2C9 and CYP3A4-mediated)
elimination_half-life = 2.5 hours
excretion = Renal
pregnancy_US = C
legal_US = Rx-only
routes_of_administration = Oral

Zileuton (INN) is an asthma drug. It blocks leukotriene synthesis by inhibiting 5-lipoxygenase, an enzyme of the eicosanoid synthesis pathway. Zileuton was introduced in 1997 by Abbot Laboratories and is now marketed by Critical Therapeutics under the brand name ZYFLO. The original four-times-per-day immediate-release formulation of zileuton, known as ZYFLO IR, was, as of March 1st, 2008, discontinued and replaced by ZYFLO CR [ [http://www.fda.gov/cder/drug/shortages/default.htm#zyflo Drug Shortages ] ]

Pharmacotherapy

Zileuton is indicated for the prophylaxis and chronic treatment of asthma in adults and children 12 years of age and older. Zileuton is not indicated for use in the reversal of bronchospasm in acute asthma attacks. Therapy with zileuton can be continued during acute exacerbations of asthma. The recommended dose of ZYFLO CR 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.

Related compounds include montelukast (Singulair) and zafirlukast (Accolate). These two compounds block the leukotriene receptor, while zileuton blocks the synthesis of leukotrienes.

Contraindications and Warnings

Zileuton frequently causes liver enzyme elevations and thus are contraindicated in patients with active liver disease or transaminase elevations greater than or equal to three times the upper limit of normal. Liver enzymes should be monitored prior to administering zileuton and repeated on a regular basis while patients are on the medication.

Zileuton is a potent inhibitor of CYP1A2 [Zyflo™ Filmtab® (zileuton) package insert. Chicago, IL: Abbott Laboratories; 1998 Mar.] [Granneman GR, Braeckman RA, Locke CS, et al. Effect of zileuton on theophylline pharmacokinetics. Clin Pharmacokinet 1995;29:77—83.] and thus has several clinically important drug interactions, such as inhibiting warfarin and theophylline metabolism. It lowered theophylline clearance significantly, doubling the AUC and prolonging half-life by nearly 25%. Because of theophylline's relation to caffeine (both being a methylxanthine, and theophylline being a metabolite of caffeine), caffeine's metabolism and clearance may also be reduced [Cafcit® (caffeine citrate) package insert. Evansville, IN: Mead Johnson & Company; 2003 May.] . The R-isomer of warfarin metabolism and clearance is mainly affected by zileuton, while the S-isomer is not (because of metabolism via different enzymes). This can lead to an increase in prothrombin time [Zyflo™ Filmtab® (zileuton) package insert. Chicago, IL: Abbott Laboratories; 1998 Mar.] .

ee also

* Lipoxygenase inhibitor

External links

* [http://www.zyflo.com Zyflo] (manufacturer's website)
* [http://www.meds-help.com/zileuton/ Zileuton] (patient information)

References