Comparison of Serum Antibiotic Concentrations Achieved in Calves

Peak serum concentrations of procaine penicillin, ampicillin trihydrate, tylosin, oxytetracycline and chloramphenicol were achieved more rapidly, reached higher maximum values and declined more rapidly by tracheal route than by i/m or s/c injection. The rapid disappearance after tracheal administration is probably caused by rapid excretion associated with the high peak serum concentration and the lack of drug reservoir at the site of administration. Chloramphenicol sodium succinate, dihydrostreptomycin sulphate and neomycin sulphate were less rapidly absorbed from the lung and achieved lower serum peaks which declined slowly. It was concluded that there was no potential advantage in using the tracheal route to achieve therapeutically effective serum antibiotic concentrations.