pharmachologic effect

Allopurinol is a structural analogue of hypoxanthine. Allopurinol, as well as its main active metabolite, oxypurinol, inhibit xanthine oxidase, an enzyme that converts hypoxanthine to xanthine, and xanthine to uric acid. Allopurinol reduces the concentration of uric acid in both serum and urine. Thus, it prevents the deposition of uric acid crystals in the tissues and (or) facilitates their dissolution. In addition to suppressing the catabolism of purines in some (but not all) patients with hyperuricemia, a large amount of xanthine and hypoxanthin becomes available for the re-formation of purine bases, which leads to inhibition of the de novo purine biosynthesis by the feedback mechanism, which is mediated by the inhibition of the hypoxanthine guanine phosphoribosyl enzyme -transferase. Other metabolites of allopurinol are allopurinol-riboside and oxypurinol-7 riboside.

Indications

Suppression of the formation of uric acid and its salts with the confirmed accumulation of these compounds (eg, gout, cutaneous tofusi, nephrolithiasis) or the estimated clinical risk of their accumulation (for example, treatment of malignant tumors can be complicated by the development of acute urinary nephropathy).

The main clinical conditions that can be accompanied by the accumulation of uric acid and its salts include:

- idiopathic gout;

- urolithiasis (formation of concrements from uric acid);

Acute uracic nephropathy;

- Tumor diseases and myeloproliferative syndrome with a high rate of renewal of the cell population, when hyperuricemia occurs spontaneously or after cytotoxic therapy;

- certain enzymatic disorders accompanied by hyperproduction of uric acid salts, for example, reduced hypoxanthine guanine phosphoribosyltransferase activity (including Lesch-Nayhan syndrome), decreased activity of glucose-6-phosphatase (including glycogenoses), increased phosphoribosyl pyrophosphate synthetase activity, increased activity of phosphoribosyl- pyrophosphate-amido-transferase, decreased activity of adenine-phosphoribosyltransferase.

Treatment of urolithiasis accompanied by the formation of 2,8-dihydroxyadenine (2,8-DHA) concrements due to decreased activity of adenine phosphoribosyltransferase.

Prevention and treatment of urolithiasis, accompanied by the formation of mixed calcium-oxalate stones in the background of hyperuricosuria, when diet and increased fluid intake were unsuccessful.