Tipiracil

Tipiracil prevents trifluridine conversion into 5-trifluoromethyl-2,4(1H,3H)-pyrimidinedione, which is an inactive major metabolite, by inhibiting the enzyme thymidine phosphorylase. Thus, tipiracil is able to increase trifluridine bioavailability. On the other hand, thymidine phsophorylase is a known platelet-derived endothelial cell growth factor and its inhibition generates an indirect antiangiogenic benefit.

Tipiracil is a thymidine phosphorylase inhibitor. Its function prevents the breakdownof the active component of trifluridine, thus increasing the bioavailability of trifluridine and boosting its systemic presence. In addition, it is reported that thymidine phosphorylase is an angiogenic factor usually overexpressed in solid tumors. There is a direct association of thymidine phosphorylase with a poor prognosis; where the tumors with an elevated expression of this enzyme tend to present an increased angiogenesis and ergo, be more malignant. Therefore, it has been suggested that tipiracil presents an aditional function by downregulating tumoral angiogenesis.

Tipiracil does not undergo much metabolism upon first pass. It is not metabolized by the liver or hepatocytes, nor by the cytochrome P450 enzymes. The only tipiracil-derived metabolite found in very small quantities in human plasma, urine or faeces is 6-hydroxymethyluracil (6-HMU) which is not unique of tipiracil. This metabolite is though to be formed either by enterobacterial metabolism. In plasma, this two metabolites can be found in a proportion of tipiracil 53.1% and 6-HMU 30.9%.

NGO10K751P

TIPIRACIL

Established Pharmacologic Class [EPC] - Thymidine Phosphorylase Inhibitor