Penicillin and dihydrostreptomycin serum concentrations after administration in single and repeated doses to feeder steers
Teske, R.H.; Rollins, L.D.; Carter, G.G.
Journal of the American Veterinary Medical Association 160(6): 873-878
1972
ISSN/ISBN: 0003-1488 PMID: 4110836 Document Number: 49640
Fourteen feeder steers were given i/m injections of procaine benzylpenicillin and dihydrostreptomycin (DSM) in fixed combination, either in four consecutive daily doses or as a single massive dose. The mean concentration of penicillin in serum from steers given a single massive dose reached a peak (7.2 units/ml) 1-3 hours after administration; concentrations were 0.25 and 0.05 unit/ml at the 24th and 36th hours after treatment, respectively. After repeated doses the mean penicillin concentration reached a peak of 2.24 units/ml about one hour after each dose; concentrations were 0.17 and 0.02 units/ml at the 12th and 24th hours after treatment, respectively. Mean DSM concentrations in serum reached a peak approximately one hour after both a single massive dose (105 mu g/ml) and after repeated daily doses (23.4 mu g/ml). Mean DSM serum concentrations after a single massive dose were 1.12 and 0.29 mu g/ml at the 24th and 48th hours, respectively, and after administration of repeated doses, concentrations of 1.16 and 0.27 were found at the 12th and 24th hours. Tissue samples were collected from 6 steers at the 30th, 60th, and 90th days after administration of a single massive dose. Residues of DSM were detected in urine from one steer at the 30th day and in muscles from the injection site and kidneys at the 30th, 60th, and 90th days. Penicillin residues were not detected in any of the samples assayed.