Zileuton-d4 is intended for use as an internal standard for the quantification of zileuton by GC- or LC-MS. Zileuton is a reversible 5-lipoxygenase (5-LO) inhibitor.1 It inhibits 5-LO activity in rat basophilic leukemia-1 (RBL-1) cell supernatant with an IC50 value of 0.5 µM. Zileuton inhibits leukotriene B4 production induced by the calcium ionophore A23187 in purified human peripheral blood polymorphonuclear leukocytes (PMNLs; IC50 = 0.6 µM). Zileuton (10 mg/kg, p.o.) prevents antigen challenge-induced increases in specific lung resistance in a sheep model of asthma at 4 to 8 hours post-challenge following administration 2 hours pre-challenge.2 Formulations containing zileuton have been used in the prophylaxis and chronic treatment of asthma.
1.Carter, G.W., Young, P.R., Albert, D.H., et al.5-Lipoxygenase inhibitory activity of zileutonJ. Pharmacol. Exp. Ther.256(3)929-937(1991) 2.Abraham, W.M., Ahmed, A., Cortes, A., et al.The 5-lipoxygenase inhibitor zileuton blocks antigen-induced late airway responses, inflammation and airway hyperresponsiveness in allergic sheepEur. J. Pharmacol.217(2-3)119-126(1992)