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 enhances 5-FU-induced cytotoxicity in various human cancer cell lines[1]. At concentrations of 20-100 μM, it decreases the rapid clearance of both trace amounts of [14C]uridine and high concentrations of non-labeled uridine in isolated rat liver perfused with an artificial oxygen carrier[2].

Benzylacyclouridine, administered either orally (p.o.) or intravenously (i.v.), effectively inhibits the rapid conversion of a tracer dose of uridine to uracil in both dogs and pigs[1]. In dogs, the compound demonstrates a half-life (t 1/2) ranging between 1.8 to 3.6 hours and achieves bioavailability levels of 85% at a dosage of 30 mg/kg and 42.5% at 120 mg/kg[1]. When administered to pigs at a dosage of 120 mg/kg, benzylacyclouridine shows a half-life (t 1/2) of 1.6 to 2.3 hours, with a bioavailability of 40%[1].