A study in the pharmacodynamics of oxytetracycline in the chicken.

Oxytetracycline HCL was administered to 24 hr. old and 1 week old chicks at a dosage of 5 mg./kg. The routes of administration were oral and intramuscular and in addition the week old chicks received the drug subcutaneously. The birds were killed in groups of 5, representing each of the routes of administration of the experiment, at the following intervals, 1 hr., 2 hr., 4 hr., 6 hr. and 24 hr. after administration. Oral administration of oxytetracycline results in very low levels of drugs in the tissues of both age groups, but the levels appeared lower and absorption less complete in the 1 week old birds. Intramuscular and subcutaneous administration resulted in higher levels in all the tissues of the birds in both age groups. Kidney and liver samples contained the highest tissue levels of oxytetracycline in all experiments, whereas lung and serum levels were in all cases very low and at some intervals entirely absent.