Zileuton is a weak inhibitor of CYP1A2  and thus has three clinically important drug interactions, which include increasing theophylline , and propranolol levels. It has been shown to lower 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, 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 (because of metabolism via different enzymes). This can lead to an increase in prothrombin time. 
My 12 year old has POTS (dysautonomia) and MCAD. He is very gifted, and lately, when he studies for long periods of time, writes a research paper, or takes tests, he becomes sick afterwards. His lung capacity is at about 70% overall, but he can’t tolerate Xopenex or most steroids. We’re trying Intal soon. I’m wondering if he isn’t low on oxygen when using brain power, but normally he is at 97-98%. If anyone has any advice or comments, please send them my way. Alec is on H1, H2 blockers, Gastrocrom, Midodrine (vasoconstrictor for POTS). He is getting headaches and episodes a few times a week, now. Will oxygen help? Any other suggestions?