Evaluation of the sulphadimidine acetylator phenotyping test in patients with reduced renal function

The acetylator phenotype of 53 hypertensive patients and 5 patients with ulcerative colitis was assessed by determination of the percentage acetylated sulphadimidine in serum and urine related to creatinine clearance. Of the 58 patients, 30 were slow and 27 rapid acetylators, one patient was indiscriminate. The fraction acetylated sulphadimidine excreted in urine tended to decrease with decreasing creatinine clearance in both slow and rapid acetylators. In a 6-hour serum sample, on the other hand, the fraction of acetylated sulphadimidine appeared to be independent of the glomerular filtration rate in rapid acetylators. In slow acetylators, however, the acetylators, fraction increased with decreasing creatinine clearance. The sulphadimidine between rapid and slow acetylators even in cases with severe renal insufficiency. Analyses of 6-hour serum samples are to be preferred but urine samples can also be used if corrected according to creatinine clearance.