Effect of oxipurinol and allopurinol riboside on whewellite crystallization: in vitro and in vivo observations.

Solubility measurements, seeded crystal growth kinetics, solution depletion adsorption studies, nucleation observations, zeta potential measurements, and measurements of in vivo intrarenal crystallization all failed to show that either oxipurinol or allopurinol riboside interacts with calcium, oxalate, or whewellite (CaC2O4.H2O) at concentrations expected in therapeutic situations. We conclude that at therapeutically expected concentrations, oxipurinol and allopurinol riboside do not affect crystallization of calcium oxalate.