Abstract
The metabolism of randomly labeled C14-tetracycline and 7-tritio-tetracycline following intraperitoneal and oral administration in the rat has been examined. Approximately 90% of the administered radioactivity in the rat was eliminated either by the urinary or fecal route. A significant portion of the remaining activity was bound as chelated tetracycline on the skeleton of the animal. A dilute formic acid solution was used to extract radioactivity from the feces and the extract was submitted to countercurrent distribution in a butanol:formic acid:water system. A single peak was obtained which agreed with that obtained from pure tetracycline treated in an identical manner.
The contents of the peak tube, when examined by paper chromatography, migrated as does authentic tetracycline. Upon treatment with acid, a derivative was generated and identified as anhydrotetracycline. This compound is known to be the major product of tetracycline so treated.
Similar techniques were applied to the unextracted urine from the rat as well as from the dog with identical results. These data show that with the exception of metal chelate formation, tetracycline is chemically unaltered by the rat. The urines from the dog also contained unchanged drug thus indicating that in this species no metabolic transformation of tetracycline had occurred.
Footnotes
- Received January 20, 1960.
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