Determination of 5-fluorouracil and tegafur in tear fluid of patients treated with oral fluoropyrimidine anticancer agent, S-1

Purpose To establish a method for the measurement of 5-fluorouracil (5-FU), and tegafur (FT) in tear samples from patients treated with oral fluoropyrimidine anticancer agent S-1. Study design Cross-sectional study. Methods High performance liquid chromatographic (HPLC) method reported for plasma samples was modified for tear samples. Simulated-tear solutions containing lactoferrin, lysozyme and standard solution containing 5-FU or FT were prepared for preliminary measurements. Tear samples from seven patients treated with S-1 were included. The tears were collected following S-1 administration using Schirmer’s strips. Results 5-FU and FT concentrations of pure standard solution without extraction process were detected as original concentration. However, on extraction, FT samples in simulated-tear solution showed a peak for 5-FU but not for FT. FT was converted to 5-FU in the extraction process. Decomposition from FT to 5-FU was suppressed when 50 mg/mL bovine serum albumin was added during extraction. The mean concentrations of 5-FU and FT in tears during S-1 treatment were 0.17 ± 0.11 and 1.94 ± 0.71 μg/mL, respectively. Conclusion A simple HPLC method to determine 5-FU and FT in tear samples was established.