The use of renal enzymes as early indication of renal toxicity after multiple-dose administration of aspirin.

Ten volunteers participated in a study comparing the effects on renal enzymes of multiple oral doses of aspirin relative to no treatment. The total urinary output was collected daily for 21 days from all subjects. The first 7 days were treatment-free. During the second 7-day period the subjects received aspirin 1500 mg 3 times daily. This was followed by another treatment-free period of 7 days. The activity of the enzymes alanine aminopeptidase and N-acetyl-beta-glucosaminidase were determined in each daily urine specimen. Statistical analysis revealed that aspirin significantly increased the output of both enzymes.