The metabolism of phenacetin in patients with renal disease

Phenacetin metabolism was investigated in 11 patients with renal disease, 9 of whom had previously abused analgesics. Comparative studies were carried out in 6 healthy adult volunteers. Following an oral dose of 1.8 Gm. of phenacetin, the mean plasma concentrations of phenacetin and unconjugated N‐acetyl‐p‐aminophenol (APAP) were similar in the patients with renal disease and the healthy volunteers. Absorption often appeared to be slow and irregular. There was marked individual variation in the plasma concentration of phenacetin and free AP AP, and the values observed at one and 2 hours varied by a factor of 4 when the healthy volunteers received different preparations of phenacetin. The 24 hour urinary recovery of phenacetin, p‐phenetidine, 2‐sulfonyloxy‐4‐ethoxyaniline, and free AP AP was essentially the same in the patients with renal disease and healthy volunteers. The renal excretion of conjugated AP AP was significantly reduced in patients with renal disease, and this reduction was correlated with the glomerular‐filtration rate. AP AP, 2‐hydroxyphenacetin, and 3‐amino‐7‐ethoxyphenoxazone were identified on thin‐layer chromatograms of glusulasehydrolyzed urine extracts, and other unidentified metabolites were observed.