febuxostat

introduction

a xanthine oxidase inhibitor introduced in 2015, as a new Rx to lower uric acid levels in patients with chronic tophaceous gout
trials suggest it may be more effective than allopurinol but does risk cessation due to causing abnormal LFTs, and commencement needs to be covered with non-steroidal anti-inflammatory drugs (NSAIDs) or colchicine for 6 months as flare ups at commencement are more likely.
other side effects appear to be similar to those of allopurinol

xanthine oxidase inhibitors create serious interactions with azathioprine and mercaptopurine

for patients with tophi, start at 40mg/d, if urate levels > 0.36mM after 2-4wks Rx, then increase to 80mg/d
trials have used doses up to 240mg/d but effectiveness was little better than 120mg/d and presumably had greater adverse effects
no dose reduction is needed if creatinine clearance > 30 mL/min and liver function is not severely impaired