Rapid determination of 5-fluorocytosine levels in blood

Levels of 5-fluorocytosine in blood were rapidly calculated by determining the amount of competition in the creatinine iminohydrolase (creatinine deiminase; EC 3.5.4.21) assay for creatinine with the Kodak Ektachem system (Eastman Kodak Co., Rochester, N.Y.). The correlation with bioassay values was extremely high (r = 0.982). Standards and samples were highly stable over time.