EFFECTS OF EXPERIMENTALLY INDUCED PASTEURELLA-HAEMOLYTICA PNEUMONIA ON THE PHARMACOKINETICS OF ERYTHROMYCIN IN THE CALF

  • 1 January 1985
    • journal article
    • research article
    • Vol. 46  (4) , 798-803
Abstract
Pneumonic pasteurellosis was produced experimentally in 3-4 mo. old Holstein bull calves by bilateral intrapulmonary administration of 5 .times. 107 to 109 colony-forming units of P. haemolytica. Of 8 calves, 4 developed minor pulmonary changes, 1 died of an apparent bacteremia within 24 h and 3 developed extensive pneumonic changes. At 1 wk before (1 dose) and at 48, 60 and 72 h (3 doses) after Pasteurella administration, the calves were given erythromycin at a dosage of 15 mg/kg, and the pharmacokinetic values were determined. There were statistically (P .ltoreq. 0.05) significant increases in the distribution and elimination rates associated with pneumonia. The elimination half life decreased from 132.7 .+-. 9.6 min in prepneumonic calves to 111.1 .+-. 13.8 minutes and 99.7 .+-. 2.6 min in calves with minor and with moderate pneumonic changes, respectively. There also was a decrease in apparent volume of distribution with pneumonia. Erythromycin tissue concentrations were determined 2 h after the last dose was given to the calves with pneumonia. Tissue concentrations in the pneumonic lung areas were as high or higher than those in nonaffected lung tissues in the same animals. Because of the increase of rate of elimination from serum in pneumonic calves, it may be advisable to use shorter dosage intervals in calves with severe respiratory tract disease.