Rasburicase is a recombinant urate oxidase and a hyperuricemia inhibitor. Rasburicase converts uric acid into allantoin, making it easier to be cleared by the kidneys and improving the elevated level of uric acid in the blood.
References:
[1]. Cammalleri L, et al. Rasburicase represents a new tool for hyperuricemia in tumor lysis syndrome and in gout. Int J Med Sci. 2007 Mar 2;4(2):83-93.