Zileuton, a 5-lipoxygenase inhibitor in rheumatoid arthritis.

The effects of zileuton, a new 5-lipoxygenase inhibitor, on leukotriene generation and clinical response in rheumatoid arthritis (RA) was studied in a 4-week randomized double blind placebo controlled study at 2 academic rheumatology centers. Zileuton decreased the mean (+/- SEM) ionophore induced synthesis of leukotriene B4 at Week 1 by 70% from 191.2 +/- 28.5 to 57.5 +/- 17.0 ng/ml. A parallel suppression of all major 5-lipoxygenase pathway products was observed. An improvement in clinical variables was observed in the zileuton and placebo treated population. No unique toxicity was identified in this study. Zileuton inhibited 5-lipoxygenase in RA with a suggestion of clinical response with limited toxicity.