Pathophysiology
Clinical meaning
Gout pharmacologic management at the NP level requires mastery of urate-lowering therapy (ULT) mechanisms and flare prophylaxis strategies. Hyperuricemia results from either uric acid overproduction (10%) or underexcretion (90%). Xanthine oxidase inhibitors (XOIs) โ allopurinol and febuxostat โ block the enzyme that converts hypoxanthine โ xanthine โ uric acid, reducing production. Uricosuric agents (probenecid, lesinurad) inhibit URAT1 transporters in the proximal tubule, increasing renal uric acid excretion. Pegloticase (recombinant uricase) converts uric acid to the more soluble allantoin for refractory tophaceous gout. ULT initiation mobilizes crystal deposits, paradoxically triggering flares through NLRP3 inflammasome activation; therefore, flare prophylaxis with low-dose colchicine (0.6 mg daily-BID) or low-dose NSAID is co-prescribed for 3โ6 months. The treat-to-target strategy aims for serum uric acid < 6 mg/dL (< 5 mg/dL in tophaceous disease). Pharmacogenomic considerations include HLA-B*5801 screening before allopurinol (risk of DRESS/SJS in carriers), CYP2C9 considerations for febuxostat, and dose adjustment for renal impairment.