[Evaluation of the optimum method of administration of a new antineoplastic agent, HCFU, based on the serum 5-FU concentration following oral administration].

The serum concentration of HCFU and its metabolites was clinically studied to obtain the most useful information for optimal methods of oral administration of a new anticancer agent. In this paper, the serum level of the only 5-FU among metabolites of HCFU was discussed. High-performance liquid chromatography was used as monitoring the agent. The serum level of 5-FU usually reached a maximum one hour after oral administration of 200mg HCFU and remained more than 0.2 to 0.3 microgram/ml for at least two hours. When administered 200mg HCFU every 6 hours (800mg/day), the serum level of 5-FU could be maintained more than 0.1 micrograms/ml for 24 hours. When administered 200mg three times after each meal (600mg/day), its level could be maintained more than 0.1 microgram/ml only for daytime, but not at night. Consequently, we suggest that the most favorable therapeutic oral administration of HCFU might be 200 mg every 6 hours (800mg/day) to maintain the serum level of 5-FU over 0.1 microgram/ml for 24 hours.