Uric Acid Treatment (Gout & Hyperuricemia)

Background

• Hyperuricemia = serum urate >6.8 mg/dL
• Only ~20% of hyperuricemic patients develop gout

• 90% of gout cases are caused by renal underexcretion (not overproduction)

Treatment Goals

1. Relieve pain and terminate acute flares quickly
2. Prevent recurrent attacks
3. Lower serum urate levels long-term

• <6.0 mg/dL for common gout
• <5.0 mg/dL for tophaceous gout (to accelerate tophus regression)

Part 1: Acute Gout Flare Treatment

1. NSAIDs

• Widely used; generally fewer side effects than colchicine
• Indomethacin and naproxen are most commonly used; no evidence one NSAID is superior to another
• Avoid in: renal insufficiency, peptic ulcer disease, patients on anticoagulation
• (Swanson's Family Medicine, Goldman-Cecil)

2. Colchicine

• One of the oldest therapies; mechanism: inhibits microtubule polymerization, reduces neutrophil recruitment, blocks NLRP3 inflammasome activation, and suppresses IL-1β
• Dosing (acute flare): 1.2 mg (2 tablets) at flare onset, then 0.6 mg 1 hour later; followed by 7-10 days of once- or twice-daily dosing depending on renal function
• Second-line due to narrow therapeutic window and high rate of GI side effects (diarrhea, nausea, vomiting) - particularly at higher doses
• (Goldman-Cecil; Goodman & Gilman's)

3. Corticosteroids

• Oral, intra-articular, or systemic
• Effective and slightly safer than NSAIDs in patients with poor renal function or colchicine intolerance
• Useful when NSAIDs and colchicine are contraindicated

4. IL-1 Inhibitors (Canakinumab / Anakinra)

• Canakinumab (anti-IL-1β monoclonal antibody): approved by European Medicines Agency for gout when colchicine, corticosteroids, or NSAIDs are ineffective or for frequent attacks
• Not FDA-approved for gout in the US (approved for autoinflammatory syndromes)
• Anakinra used off-label for refractory flares
• (Goodman & Gilman's, p. 461)

Part 2: Long-Term Urate-Lowering Therapy (ULT)

• Recurrent gout flares (typically 2+ per year)
• Tophaceous gout
• Gout with chronic kidney disease or urolithiasis
• Secondary hyperuricemia (malignancy, Lesch-Nyhan syndrome)

A. Xanthine Oxidase Inhibitors (XOIs) - First-Line ULT

Allopurinol (first-line)

• Purine analog; competitively inhibits xanthine oxidase; active metabolite oxypurinol does most of the sustained inhibition (t1/2 ~18-30 h)
• Starting dose: 100 mg/day (lower in CKD), increase by 100 mg increments weekly
• Usual maintenance: 300 mg/day; doses up to 800 mg/day for hematological malignancies
• Adverse effects: Generally well tolerated. Hypersensitivity reactions (rash, urticaria) can occur after months/years. Rarely: Stevens-Johnson syndrome / toxic epidermal necrolysis - risk is higher in HLA-B*5801 carriers (common in Han Chinese, Korean, Thai populations) and those with renal impairment
• (Goodman & Gilman's, p. 546-557)

Febuxostat (second-line)

• Potent selective nonpurine xanthine oxidase inhibitor - not affected by renal function adjustments as much as allopurinol
• 40 mg/day lowers uric acid similarly to allopurinol 300 mg/day; higher doses (80-120 mg) are more potent
• Preferred when allopurinol is contraindicated or fails (e.g., allopurinol hypersensitivity)
• Caution: cardiovascular safety concerns have been raised (CARES trial); use with caution in patients with established cardiovascular disease
• (Goodman & Gilman's; Katzung's 16th ed.)

B. Uricosuric Agents - Second-Line or Add-On

C. Uricase Agents - Refractory/Severe Gout

Pegloticase

• Recombinant PEGylated uricase; converts uric acid → allantoin (highly soluble)
• Reserved for severe refractory tophaceous gout unresponsive to other agents
• IV infusion every 2 weeks
• Risk of infusion reactions and immunogenicity; monitoring required

Rasburicase

• Recombinant uricase; used for hyperuricemia from tumor lysis syndrome (TLS)
• Not used for chronic gout management

Part 3: Non-Pharmacologic Management

• Weight loss (obesity is a major risk factor)
• Reduce high-purine foods (red meat, organ meats, shellfish)
• Limit alcohol (especially beer) and fructose-sweetened beverages
• Increase vegetable intake (even high-purine vegetables lower uric acid)
• Adequate hydration (urine output >2 L/day helps prevent urate crystals)
• Review medications: thiazide diuretics, low-dose aspirin, cyclosporine can raise uric acid
• Note: Dietary changes alone lower serum urate only 10-20% - usually insufficient without pharmacotherapy

Part 4: Special Situations

Recent Evidence (2024-2026)

• A 2024 meta-analysis (PMID 39636389) found urate-lowering therapy reduces all-cause and cardiovascular mortality in gout and hyperuricemia.
• A 2025 systematic review (PMID 39794008) confirmed SGLT2 inhibitors (e.g., empagliflozin, dapagliflozin) significantly reduce hyperuricemic events - a clinically useful uricosuric-like benefit in patients who also have diabetes or heart failure.
• A 2025 meta-analysis (PMID 39711080) showed gout flares increase after stopping anti-inflammatory prophylaxis, supporting continued prophylaxis during ULT initiation.

Quick Summary Diagram

Acute Gout Flare
├── NSAIDs (first-line if no contraindications)
├── Colchicine (1.2 mg + 0.6 mg 1h later)
├── Corticosteroids (if NSAID/colchicine contraindicated)
└── IL-1 inhibitors (canakinumab/anakinra - refractory)

Urate-Lowering Therapy (long-term)
├── XOI: Allopurinol (1st line) → start 100 mg, titrate to target
├── XOI: Febuxostat (2nd line, allopurinol allergy/failure)
├── Uricosurics: Probenecid, lesinurad (add-on or 2nd line)
└── Pegloticase (IV, severe refractory tophaceous gout)

Targets: <6 mg/dL (common gout) | <5 mg/dL (tophaceous gout)