Anti-Gout Medications: Key Points

Jul 12, 2024

Anti-Gout Medications Lecture

Overview

  • Anti-gout medications treat gout (form of inflammatory arthritis).
  • Cause of gout: Hyperuricemia (excess uric acid in the blood).
  • Uric acid forms monosodium urate crystals in joints/kidneys.
  • Meds work by preventing uric acid buildup or reducing inflammation.

Uric Acid & Hyperuricemia

  • Uric acid: Waste product of purine metabolism.
    • Purines → Hypoxanthine → Xanthine (by xanthine oxidase) → Uric acid.
  • Normal levels: 1.5-6 mg/dL (women), 2.5-8 mg/dL (men).
  • Solubility threshold: >6.8 mg/dL → crystal deposition.

Types of Anti-Gout Medications

  • Chronic Gout Medications: Prevent uric acid buildup.
  • Acute Gout Medications: Reduce inflammation.

Chronic Gout Medications

  1. Xanthine Oxidase Inhibitors

    • Allopurinol:
      • Mechanism: Competitive inhibition of xanthine oxidase.
      • Converted to active metabolite Oxypurinol (non-competitive inhibitor).
      • Decreases uric acid, increases soluble hypoxanthine/xanthine.
      • Other uses: Lymphoma/leukemia (tumor lysis syndrome).
      • Side effects: GI issues, rash.
      • Risk: Bone marrow suppression with immunosuppressive meds.
    • Febuxostat:
      • Non-purine xanthine oxidase inhibitor.
      • Used if allopurinol is intolerable.
      • Side effects: GI disturbance, headache, liver problems.

  2. Uracosuric Medications

    • Probenecid & Sulfinpyrazone:
      • Inhibit renal tubular reabsorption of uric acid.
      • Interaction: Can elevate blood uric acid at low doses.
      • Competes with other weak acids (penicillin, cephalosporins, aspirin).

  3. Recombinant Urate Oxidase

    • Pegloticase & Rasburicase:
      • Convert uric acid to more soluble allantoin.
      • Indications: Refractory gout (pegloticase), tumor lysis syndrome (rasburicase).
      • Side effects: Anaphylaxis, hemoglobinemia, hemolysis (G6PD deficiency).

Acute Gout Medications

  1. NSAIDs (e.g., Indomethacin, Ibuprofen):

    • Mechanism: Inhibition of cyclooxygenase (decreases prostaglandins).
    • Caution: Avoid aspirin (competes with uric acid in renal excretion).

  2. Glucocorticoids (e.g., Methylprednisolone, Prednisone):

    • Mechanism: Inhibit phospholipase A2 (reduces prostaglandins).
    • Administration: Oral, parenteral, intra-articular.

  3. Colchicine:

    • Mechanism: Inhibits tubulin polymerization (reduces neutrophil migration/inflammation).
    • Indications: Prophylaxis of gout attacks, familial Mediterranean fever.
    • Contraindications: Kidney, liver, GI issues.
    • Side effects: GI distress, peripheral neuropathy, rhabdomyolysis, renal damage, bone marrow suppression.

Mnemonics & Study Aids

  • Chronic Gout Meds in the Kitchen:
    • Xanthine Oxidase Inhibitors:
      • Chefs: Ox (oxypurinol) and Owl pouring oil (allopurinol).
      • Boss: Fabulous Fox (febuxostat).
      • Tumor: Tumor lysis syndrome indication.
      • Side effects: Dirty hats (GI distress), red dots (rash), bones & dead WBCs (bone marrow suppression).
    • Uracosuric Meds:
      • Butterfly sipping sink (Probenecid).
      • Pyrozonic sink (Sulfinpyrazone).
      • Discarded pen & spring (penicillin & aspirin interaction).
    • Recombinant Urate Oxidase:
      • Restaurant owners: Pig (pegloticase) and Raccoon (rasburicase).
      • Indications: Pig (urate crystal), Racoon (tumor lysis syndrome).
      • Contraindications: G6 (G6PD deficiency).
      • Side effects: Chocolate blood (hemoglobinemia), swollen faces (anaphylaxis).
  • Acute Gout Meds in the Dining Area:
    • NSAIDs:
      • Ibis (ibuprofen), dough (indomethacin).
      • Discarded spring (aspirin contraindication).
    • Glucocorticoids: Predatory shark (prednisone).
    • Colchicine: Cold chicken (colchicine).
      • Flaming pita (Mediterranean fever).
      • Vomiting person (GI distress, peripheral neuropathy, rhabdomyolysis, renal toxicity, bone marrow suppression).

Summary

  • Anti-Gout Medications: Treat gout, prevent uric acid buildup, reduce inflammation.
  • Chronic Gout Medications: Xanthine oxidase inhibitors (allopurinol, febuxostat), uracosuric drugs (probenecid, sulfinpyrazone), recombinant urate oxidase (pegloticase, rasburicase).
  • Acute Gout Medications: NSAIDs, glucocorticoids, colchicine.