Pharmacokinetics and metabolic inertness of doxycycline in young pigs
Riond, J.L.; Riviere, J.E.
American Journal of Veterinary Research 51(8): 1271-1275
1990
ISSN/ISBN: 0002-9645 PMID: 2386327 Document Number: 363979
The disposition of doxycycline hyclate after IV administration of 20 mg/kg of body weight was studied in 6 pigs. Median elimination half-life, estimated in 4 pigs, was 3.92 hours. Mean (.+-. SEM) total body clearance was 1.67 .+-. 0.18 ml/min/kg, and mean apparent volume of distribution at steady state was 0.53 .+-. 0.04 L/kg. In 2 pigs, secondary peaks in the logarithmic serum concentration-time profile suggested discontinuous enterohepatic cycling, and precluded using these pigs in the pharmacokinetic analysis. The extent of doxycycline binding to serum protein was 93.1 .+-. 0.2%. Serum or urine from 3 of the pigs was analyzed by use of photodiode array detection and mass spectrometry of a high-performance liquid chromatographic column effluent. These procedures documented lack of doxycycline biotransformation in pigs. It is concluded that, despite an elimination half-life shorter than that reported in other species, doxycycline may be a valuable antimicrobial drug for use in swine practice, pending the development of appropriate formulations.