Blood Levels and Urinary Excretion in Normal Subjects after Ingestion of Tetracycline Analogues. ∗ †

Conclusions

Blood levels after ingestion of a single dose of 1 g of tetracycline are some-what higher and better sustained than those resulting from a similar dose of either oxytetracycline Terramycin) or chlortetracycline Aureomycin). High concentrations appear rapidly in the urine after ingestion of each of these 3 analogs and persist over a period of 48 hours. After that, appreciable concentrations of these antibiotics continue to be excreted for more than a week after a single oral dose of 1.0 g Untoward gastrointestinal symptoms, particularly diarrhea, were frequent after a single oral dose for 1.0 g of oxytetracycline, they were observed, but less frequently after chlorteracycline, and did not occur after the same dose of tetracycline