URIC-ACID LOWERING EFFECT OF OXIPURINOL SODIUM IN HYPERURICEMIC PATIENTS - THERAPEUTIC EQUIVALENCE TO ALLOPURINOL

Objective, Oxipurinol has been shown to be sufficiently absorbed after oral administration as a rapid release preparation of oxipurinol sodi um. We compared the uric acid lowering effect of allopurinol and oxipu rinol. Methods. In a multicenter, randomized, double blind crossover t rial in 99 hyperuricemic patients with normal renal function we invest igated the uric acid lowering effect of oxipurinol sodium (O) in daily amounts equimolar to 300 mg allopurinol (A). Mean pretreatment plasma uric acid concentrations in groups A/O and O/A were 8.3 +/- 1.4 and 8 .7 +/- 1.4 mg/dl, respectively. Results, In group A/O the mean plasma uric acid decreased to 5.4 +/- 1.2 mg/dl with allopurinol treatment, a nd increased slightly to 5.7 +/- 1.3 mg/dl during the consecutive oxip urinol period. In group O/A plasma uric acid declined to 6.0 +/- 1.4 m g/dl with oxipurinol and was 5.6 +/- 1.3 mg/dl at the end of the allop urinol period. The overall average reduction compared to baseline was 3.0 mg/dl with allopurinol and 2.6 mg/dl with oxipurinol. The differen ce between the 2 treatments was small but significant (multiple p = 0. 027, 2 tailed). The corresponding mean plasma oxipurinol concentration s were 9.24 mu g/dl at the end of the alloplurinol period and 9.9 mu g /dl after treatment with oxipurinol (NS). Conclusion. Oxipurinol is we ll absorbed and sufficiently effective in hyperuricemic patients when administered as a rapid release preparation of oxipurinol sodium. Oxip urinol sodium could be a substitute for allopurinol in hyperuricemic p atients, and possibly also with new uses for allopurinol.