Allopurinol

**Semantic type:** Organic Chemical|Pharmacologic Substance

**Definition:** A structural isomer of hypoxanthine. Allopurinol inhibits xanthine oxidase, an enzyme that converts oxypurines to uric acid. By blocking the production of uric acid, this agent decreases serum and urine concentrations of uric acid, thereby providing protection against uric acid-mediated end organ damage in conditions associated with excessive production of uric acid, i.e. the massive cell lysis associated with the treatment of some malignancies. (NCI04)

**Synonyms:** - 1,5-Dihydro-4H-pyrazolo[3,4-d]pryimidin-4-one - 1,5-Dihydro-4H-pyrazolo[3,4-d]pyrimidin-4-one - 1H-Pyrazolo[3,4-d]pyrimidin-4-ol - 1H-Pyrazolo[3,4-d]pyrimidin-4-ol - 4'-HPP - 4-Hydroxypyrazolo[3,4-d]pyrimidine - ALLOPURINOL - Lopurin - Sigapurol - Zurinol - allopurinol