[Measurement of 5'-deoxy-5-fluorouridine (5'-DFUR) by high-performance liquid chromatography and studies on pharmacokinetics of 5'-DFUR and 5-fluorouracil by oral and intravenous administration].

The authors have made clear that 5'-deoxy-5-fluorouridine (5'-DFUR), a derivative of 5-fluorouracil (5-FU), is activated by thymidine phosphorylase with has a particularly high activity in human malignant tumors. This derivative therefore, has fewer side-effects and can be expected to produce a greater antitumor effect when administered to cancer patients. Blood levels of 5'-DFUR and 5-FU were then observed with time after oral or intravenous 5'-DFUR administration in order to study its clinical effect. First, a method for measurement of 5'-DFUR and 5-FU was devised using high-performance liquid chromatography (HPLC). The results obtained using this method revealed that for intravenous administration both 5'-DFUR and 5-FU showed rapid drops in blood level while for oral administration both showed blood level peaks after one hour which were maintained of the same level for two hours, decreasing gradually thereafter. 5-FU showed a blood level peak after one hour, decreasing gradually thereafter. From the above results it was proved that a relatively high percentage of orally administered 5'-DFUR was absorbed from the intestine.