Abstract
Tetracycline is absorbed from the dog stomach, duodenum and ileum hut relatively little absorption occurs from the colon. Absorption from the small intestine is extremely rapid, peak serum levels being attained within 30 minutes. Absorption from the stomach is remarkable but peak levels are reached much more slowly than from the intestine and are maintained for a considerably longer time. The actual amount of tetracycline which is absorbed during the period examined is small in relation to the dose administered. Absorption appears to be a passive diffusion phenomenon.
Excretion data on tetracycline are presented. Fifty to 60% of an intravenously administered dose is consistently excreted within 24 hours regardless of the initial dose. Another 20 to 25% is excreted in the next 48 to 72 hours.
Renal clearance data provide a total tetracycline/creatinine ratio of 0.33 in unanesthetized dogs. Protein binding studies indicate that 69% of the blood complement of tetracycline is protein bound. Assuming that in vitro protein binding data reliably reflect the amount of drug filterable at the glomeruli, the filterable tatracycline/creatinine ratio then becomes 1.04. Considering all of the evidence presented, it is concluded that the renal excretion of tetracycline occurs solely by way of glomerular filtration with the tubules playing littleor no role.
Footnotes
- Received October 31, 1958.
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