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Veterinary Medicine International
Volume 2014, Article ID 789353, 7 pages
Research Article

A Population Pharmacokinetic Approach to Describe Cephalexin Disposition in Adult and Aged Dogs

1Farmacología, Facultad de Ciencias Veterinarias, Universidad de Buenos Aires. Chorroarín 280, 1427 Buenos Aires, Argentina
2Unidad de Farmacocinética Clínica-CONICET, Hospital de Pediatría JP Garrahan, Combate de los Pozos 1881, 1245 Buenos Aires, Argentina

Received 8 July 2014; Accepted 9 October 2014; Published 6 November 2014

Academic Editor: Guillermo Virkel

Copyright © 2014 Ana Paula Prados et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


This study was conducted in order to characterize the pharmacokinetics of orally administered cephalexin to healthy adult and aged dogs, using a population pharmacokinetic approach. Two hundred and eighty-six cephalexin plasma concentrations obtained from previous pharmacokinetic studies were used. Sex, age, pharmaceutical formulation, and breed were evaluated as covariates. A one-compartment model with an absorption lag-time (Tlag) best described the data. The final model included age (adult; aged) on apparent volume of distribution (Vd/F), apparent elimination rate (ke/F), and Tlag; sex (female; male) on ke/F, and breed (Beagle; mixed-breed) on Vd/F. Addition of the covariates to the model explained 78% of the interindividal variability (IIV) in Vd/F, 36% in ke/F, and 24% in Tlag, respectively. Formulation did not affect the variability of any of the pharmacokinetic parameters. Tlag was longer, whereas Vd/F and ke/F were lower in aged compared to adult animals; in female aged dogs ke/F was lower than in male aged dogs; however, the differences were of low magnitude. Different disposition of cephalexin may be expected in aged dogs.