Thiopurine metabolites variations during co-treatment with aminosalicylates for inflammatory bowel disease: Effect of N-acetyl transferase polymorphisms

Figure 1 6-thioguanine nucleotides concentration and N-acetyl transferase 1 acetylator status during co-treatment of azathioprine with 5-aminosalicylic acid and after the interruption of the aminosalicylate. A: With 5-aminosalicylic acid; B: Without 5-aminosalicylic acid. A total of 36 samples of peripheral blood were collected from 12 patients to measure azathioprine metabolites; on average, 3 samples for patient were collected (range: 2-4). Among these, 19 were obtained during treatment with the thiopurines and 5-aminosalicylic acid (panel A) and 17 during treatment with the thiopurine alone (panel B). Samples were taken from the same patient with an interval of at least one month. 6-thioguanine nucleotides concentration is expressed as pmol/8 × 10⁸ erythrocytes.