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In recent years, studies of the metabolism of salicylates have been concerned primarily with the concentration of salicylates and metabolities in various body fluids. The absorption of salicylates and hydrolysis of acetylsalicylic acid have received little attention. The presence of conjugated forms of salicylates in plasma.is still in dispute. Brodie, Udenfriend and Coburn (1) were unable to demonstrate the presence of appreciable quantities of salicyluric acid in the plasma, although Kapp and Coburn (2) had shown it to be one of the main conjugated forms in the urine. Lester, Lollie and Greenberg (3) reported that in a 75 Kg. person, 27 per cent of the salicylate in the plasma existed in a conjugated form thirty minutes after ingestion of a 0.65 gm. dose of acetylsalicylic acid. They measured the difference in salicylate levels before and after hydrolysis and assumed the conjugated form was acetylsalicylic acid. Smith and co-workers (4) found no free acetylsalicylic acid in the plasma of men or dogs one hour after intravenous administration or at any time after oral administration. One of the outstanding difficulties in previous investigations has been the lack of a method for the identification of unhydrolyzed aspirin in a body fluid or tissue. In an attempt to solve this problem, we synthesized acetylsalicylic acid labelled with C14 in the acetyl group (5). Hydrolysis of this radioactive aspirin would produce salicylic acid and an acetate group containing C14. If unhydrolyzed radioactive aspirin were present in a fluid or tissue, it could be detected by a combination of radioactivity measurements and chemical techniques.

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Journal Title

Proceedings of the Iowa Academy of Science





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©1955 Iowa Academy of Science, Inc.



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