Determination of 6-mercaptopurine and azathioprine in plasma by high-performance liquid chromatography

J Chromatogr. 1979 Jul 21;163(3):281-8. doi: 10.1016/s0378-4347(00)81415-2.


Using 1-ml plasma samples, levels of 6-mercaptopurine (6MP) as low as 5 ng/ml and azathioprine (AZA) as low as 40 ng/ml can be detected using a high-performance liquid chromatography reversed-phase column procedure following extraction. Both compounds were stable in frozen plasma for seven weeks. AZA stability in blood was temperature dependent; the half-lives of AZA breakdown to 6MP at 37 degrees were 28 and 46 min in blood drawn from two rhesus monkeys. Plasma levels of 6MP were measured in a rhesus monkey following 6MP (1.47 mg/kg) and AZA (3 mg/kg) intravenous administration. 6MP levels were also measured in three renal transplant patients on daily 50- and 100-mg AZA doses. Peak levels (45-75 ng/ml) were reached within an hour and 6MP levels were detected for up to 7 h.

Publication types

  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Azathioprine / blood*
  • Azathioprine / pharmacology
  • Azathioprine / therapeutic use
  • Chromatography, High Pressure Liquid / methods
  • Haplorhini
  • Humans
  • Macaca mulatta
  • Mercaptopurine / blood*
  • Mercaptopurine / pharmacology


  • Mercaptopurine
  • Azathioprine