Studies on Binding of Tetracyclines by Dog and Human Plasma. ∗

Abstract

Summary

Dialysis equilibrium studies under physiological conditions of temperature and pH with tetracycline, demethylchlortetracycline and chlortetracycline have shown that degree of binding by dog and human plasma for drug concentrations ranging from 1-10 μg/ml was approximately twice as much for chlortetracycline (61%) as for tetracycline (34%), while demethylchlortetracycline was intermediate. These experiments also showed that each tetracycline was bound to a similar extent by dog and human plasma. A study with tetracycline showed that: a) approximately the same results were obtained when the equilibrium was carried out at 37°C or at 4°C; and b) binding increased with increasing alkalinity over the pH range of 6.7 to 8.1.