title: Determination of 6-thioguanine and 6-methylmercaptopurine metabolites in renal transplantation recipients and patients with glomerulonephritis treated with azathioprine.
abstract: The metabolism of azathioprine (AZA) was studied by monitoring the concentrations of red blood cell (RBC) 6-thioguanine nucleotides (6-TGN) and of 6-methylmercaptopurine metabolites (6-mMP) in 27 renal transplantation recipients and in 10 patient subjects with glomerulonephritis (GN). Concentrations of 6-TGNs and 6-mMP metabolites were measured using high-performance liquid chromatography (HPLC). Six patients from the group of renal transplantation recipients were also administered allopurinol. Median values of RBC 6-TGN and of 6-mMP metabolites concentrations in 21 renal transplantation recipients (without allopurinol) were 122 pmol/8x10(8) RBCs (range, <60-298) and 280 pmol/8x10(8) RBC (range, <150-1330), respectively; there was no correlation between concentrations of 6-TGN and of 6-mMP metabolites. The group of 21 renal transplantation recipients received different AZA doses (100 or 50 mg/d) related to clinical symptoms of AZA intolerance. The median values of 6-TGN concentrations in these subgroups were 131 and 122 pmol/8x10(8) RBCs and were not significantly different. Median values of 6-TGN concentrations in patients given allopurinol were significantly higher, despite AZA dose reduction, compared with the group without allopurinol and were equal to 363 and 122 pmol/8x10(8) RBC, p < 0.004, respectively. No significant differences were found between the concentrations of 6-mMP metabolites in either group. In the group of renal transplantation recipients, a significant correlation between white blood cell (WBC) count and 6-TGN concentration was established (r(s) = -0.59, p < 0.005). In the group of GN patients, the median values of 6-TGN and of 6-mMP metabolites concentrations were 108 pmol/8x10(8) RBCs (range, 0-297) and 420 pmol/8x10(8) RBC (range, 0-1440), respectively. There were no significant correlations between either the WBC count and 6-TGN concentrations or between 6-TGN concentrations and 6-mMP metabolites. We expect the results of our study to provide indications for better individualization of AZA therapy.
authors.affiliation: Department of Physical Chemistry, Karol Marcinkowski University of Medical Sciences, Poznań, Poland.
authors.forename: M
authors.initials: M
authors.lastname: Chrzanowska
authors.forename: M
authors.initials: M
authors.lastname: Krzymański
mesh_terms: D000328:Adult; D000493:Allopurinol / Q000097:blood / Q000493:pharmacokinetics; D000963:Antimetabolites / Q000097:blood / Q000493:pharmacokinetics; D001379:Azathioprine / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D004912:Erythrocytes / Q000378:metabolism; D005260:Female; D005921:Glomerulonephritis / Q000097:blood* / Q000188:drug therapy; D006801:Humans; D007166:Immunosuppressive Agents / Q000008:administration & dosage / Q000097:blood / Q000493:pharmacokinetics*; D016030:Kidney Transplantation; D008297:Male; D015122:Mercaptopurine / Q000031:analogs & derivatives* / Q000378:metabolism; D008875:Middle Aged; D013866:Thioguanine / Q000378:metabolism*
chemical_list: D000963:Antimetabolites; D007166:Immunosuppressive Agents; D000493:Allopurinol; C010240:6-methylthiopurine; D015122:Mercaptopurine; D013866:Thioguanine; D001379:Azathioprine