Zileuton is an orally active inhibitor of 5-lipoxygenase, and thus inhibits leukotrienes (LTB4, LTC4, LTD4, and LTE4) formation. Zileuton is used for the maintenance treatment of asthma. Zileuton is a weak inhibitor of CYP1A2 and thus has three clinically important drug interactions, which include increasing theophylline, and propranolol levels. Because of theophylline's relation to caffeine , caffeine's metabolism and clearance may also be reduced, but there are no drug interaction studies between zileuton and caffeine. The R-isomer of warfarin metabolism and clearance is mainly affected by zileuton, while the S-isomer is not. Zileuton is an active oral inhibitor of the enzyme 5-lipoxygenase, which forms leukotrienes from arachidonic acid. The chemical name of zileuton is (±)-1-(1-Benzo[b]thien-2-ylethyl)-l-hydroxyurea.
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