[Distribution, concentration and the interrelationship of free and bound tetracycline in the body of animals with multiple administrations].

When tetracycline was used for a long period of time, constant changes in the distribution regularities of free and bound fractions of the drug were observed. The changes were accompanied by a successive increase in the concentrations of both the fractions in the animal organs, tissues and fluids, as well as by a change in their levels, accumulation rate and percentage content.