The effect of antipyrine and rifampicin on the excretion of renal enzymes in human urine.

Two well-known drugs that induce the liver microsomal enzyme system in man were administered to 3 different groups of healthy male volunteers. Antipyrine 1200 mg and rifampicin in two different doses of 600 mg or 1200 mg daily were given orally to each group over a period of seven days. The extent of liver microsomal enzyme induction was assessed by estimating antipyrine elimination, serum gamma-glutamyl-transferase (GGT) activity and the urinary excretion rate of 6-beta-hydroxycortisol. In addition, possible effects on renal enzymes were monitored by measuring gamma-glutamyltransferase (GGT) and beta-glucuronidase (GRS) urinary excretion rates before and after drug administration. The possibility of a direct toxic effect on the renal tubular epithelium following drug administration was assessed by the measurement of urinary beta-N-acetylglucosaminidase (AGS) activity, total protein and glucose. Antipyrine plasma clearance and 6-beta-OHF excretion rates increased significantly in the groups treated with antipyrine or rifampicin, while serum GGT activities were enhanced only following antipyrine. Antipyrine administration increased urinary GGT excretion both immediately and one week after cessation of drug administration, but no changes were found following the administration of rifampicin. GRS, AGS, total protein and glucose excretion in urine remained unchanged during and after the administration of each individual drug. Based on these findings, the increased urinary GGT excretion observed following antipyrine treatment may be due to an inducing effect on the renal tubular cells, as no evidence for a toxic renal damage was found.(ABSTRACT TRUNCATED AT 250 WORDS)