An enzymatic method for 5-fluorocytosine

C. M. Huang, M. H. Kroll, M. Ruddel, R. G. Washburn, J. E. Bennett

Research output: Contribution to journalArticlepeer-review


We developed an enzymatic method for determination of 5-fluorocytosine in serum, using creatine iminohydrolase (EC, the Cobas-Bio analyzer, and an extant ammonia method. Analytical recovery (y) of drug added to serum (x) was good, with y = 0.97x - 0.7, S(y·x) = 3.6, r = 0.997 (n = 65) over the range 6.25 to 150 mg/L. Comparison with and HPLC method (x) showed good agreement: y = 0.98x + 1.34, S(y·x) = 3.7 (n = 37), as analyzed with the Deming debiased regression. Precision was good, CVs being <3% for within-run and <6% for between-run controls. Ammonia, amphotericin B, glucose, urea, and hemolysis do not interfere, but bilirubin shows analyte-dependent interference and lipemia interferes when triglycerides exceed 5 g/L. This assay is accurate, inexpensive, and easy to perform. It can be easily adapted for routine or emergency use.

Original languageEnglish (US)
Pages (from-to)59-62
Number of pages4
JournalClinical chemistry
Issue number1
StatePublished - 1988

ASJC Scopus subject areas

  • Clinical Biochemistry
  • Biochemistry, medical


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