ABSORPTION FATE AND EXCRETION OF PHENACETIN AND N-ACETYL-P-AMINOPHENOL IN RENAL INSUFFICIENCY

In 13 patients with decreased glomerular filtration rate (24 h creatinine clearance 3-64 ml/min) of different etiology and in 3 persons with normal kidney function unconjugated and total N-acetyl-p-aminophenol, the main metabolite of phenacetin, was determined in plasma and urine 1, 4, 8, 24 and 72 hours after ingestion of 1,5 g of phenacetin in capsules orally. The gastrointestinal resorption of phenacetin in patients with kidney insufficiency is not decreased nor delayed. Hepatic binding of the free metabolite was similar to the controls. However, the plasma concentrations of the unconjugated and the bound metabolite surpass many times that of the controls and remain increased for days in the case when kidney function is markedly decreased. In 29 male and 34 female patients with or without kidney insufficiency of divers etiology statistically significant correlation (p<0,005) between the excretion of free and bound N-acetyl-p-aminophenol and the 24 h creatinine clearance was measured after ingestion of 0,5 g in capsules orally (correlation coefficient r=0,454 for males and r=0,547 for females). A difference in the excretion for patients with or without regular intake of phenacetin containing analgesics does not exist. It is concluded that a decrease of glomerular elimination of N-acetyl-p-aminophenol is present with decreased kidney function. © 1968 Springer-Verlag.