how do you say allopurinol

Allopurinol: A Xanthine Oxidase Inhibitor

Allopurinol is a medication primarily used to lower uric acid levels in the blood. It achieves this by inhibiting the enzyme xanthine oxidase, a key enzyme in the purine metabolism pathway responsible for the production of uric acid.

Mechanism of Action

Xanthine oxidase catalyzes the oxidation of hypoxanthine to xanthine and xanthine to uric acid. Allopurinol structurally resembles hypoxanthine, acting as a competitive inhibitor of xanthine oxidase. Furthermore, allopurinol is metabolized to oxypurinol, a potent and long-lasting inhibitor of xanthine oxidase.

Pharmacokinetics

Allopurinol is well-absorbed orally. It undergoes extensive hepatic metabolism, primarily to oxypurinol. Oxypurinol has a much longer half-life than allopurinol, contributing to the sustained inhibitory effect on xanthine oxidase.

Therapeutic Uses

  • Primary hyperuricemia: Prevention and treatment of gout attacks, including acute gouty arthritis and tophi formation.
  • Secondary hyperuricemia: Management of elevated uric acid levels associated with certain cancers, myeloproliferative disorders, and other conditions.
  • Nephrolithiasis (kidney stones): Prevention of uric acid kidney stone formation.
  • Tumor lysis syndrome (TLS): Prevention and treatment of TLS, a potentially life-threatening complication of cancer treatment.

Adverse Effects

Common side effects include rash, gastrointestinal upset, and headache. More serious but less frequent adverse effects include hypersensitivity reactions (such as Stevens-Johnson syndrome), liver dysfunction, and bone marrow suppression. Careful monitoring is required, especially in patients with pre-existing renal or hepatic impairment.

Drug Interactions

Allopurinol may interact with several medications, including azathioprine, mercaptopurine, and ciclosporin. Concurrent use requires careful dose adjustment and monitoring to prevent toxicity.

Contraindications

Allopurinol is contraindicated in patients with known hypersensitivity to the drug or its components. Caution is advised in patients with impaired renal or hepatic function.