Uridine triacetate is used to treat an overdose of capecitabine or fluorouracil. In addition, it is used as a pyrimidine analog for uridine replacement indicated for the treatment of hereditary orotic aciduria. Following oral administration, uridine triacetate is deacetylated by nonspecific esterases present throughout the body, yielding uridine in the circulation. Uridine competitively inhibits cell damage and cell death caused by fluorouracil. Uridine can be used by essentially all cells to make uridine nucleotides, compensating for the genetic deficiency in synthesis in patients with hereditary orotic aciduria. When intracellular uridine nucleotides are restored into the normal range, overproduction of orotic acid is reduced by feedback inhibition, so that urinary excretion of orotic acid is also reduced. Adverse reactions occurring in >2% of patients receiving uridine triacetate included vomiting, nausea, and diarrhea. In vitro data showed that uridine triacetate was a weak substrate for P-glycoprotein. Due to the potential for high local (gut) concentrations of the drug after dosing, the interaction of uridine triacetate with orally administered P-gp substrate drugs cannot be ruled out.