THE PRESENCE OF ASPIRIN IN HUMAN PLASMA AFTER ORAL ADMINISTRATION

¹ Dept. of Pharmacology, The George Washington University School of Medicine, Washington 5, D. C.

l-C¹⁴ Aspirin and C¹⁴-carboxyl-labeled aspirin were prepared.

The presence of aspirin and salicylic acid in the plasma after oral administration of aspirin to normal subjects was established by radioactivity, fluorescence evoked by ultraviolet light, and color development after separation of the metabolites by paper chromatography.

Aspirin was found to he present in the plasma of humans for approximately two hours after administration, at levels less than 2 mgm. per cent. It was calculated that at least a major portion of the salicylate found in the plasma during the first two hours after drug administration had been formed by the hydrolysis of aspirin after absorption.