Benzylacyclouridine (BAU) is a powerful and selective inhibitor of uridine phosphorylase, the initial enzyme involved in uridine catabolism. Additionally, it can regulate the cytotoxic adverse effects of 5-fluorouracil (5-FU) and its derivatives.

Benzylacyclouridine increases 5-FU-induced cytotoxicity in a number of human cancer cell lines[1]. Benzylacyclouridine (20-100 μM) reduces the rapid clearance of trace amounts of either [ 14 C]uridine or hyperphysiologic concentrations of non-labeled uridine by the isolated rat liver perfused with an artificial oxygen carrier[2].

Benzylacyclouridine (p.o. or i.v.) arrests the rapid degradation of a tracer dose of uridine into uracil in dogs and pigs[1]. Benzylacyclouridine exhibits the t 1/2 of 1.8-3.6 h in dogs, with bioavailability levels of 85% (30 mg/kg) and 42.5% (120 mg/kg)[1]. Benzylacyclouridine (120 mg/kg) exhibits the t 1/2 of 1.6-2.3 h, with a bioavailability of 40% in pigs[1].