Bridging pharmacokinetics between herbivorous mammal species by allometric analysis: A case study of ceftiofur

The objective of the present study was to analyze the relationship between pharmacokinetic parameters of cephalosporine antibiotic ceftiofur in mammals and the respective body weight (W), using reported data from different authors. The parameters of interest: clearance (ClB), volume of distribution at steady state (Vss) and elimination half-life were correlated across mammal species, as a function of W using the conventional allometric equation Y=aWb, where Y is the pharmacokinetic parameter, W is the body weight, a is the allometric coefficient (intercept) and b is the exponent that describes the relationship between the pharmacokinetic parameter and W. Our estimates Cl=0.155W0.82; Vss=1.01W1.03, indicated that the increase in these parameters with W approximates a linear power relationship with slopes being specific for the investigated substance. Overall, the results of this study indicated that it is possible to use allometry to predict pharmacokinetic variables of ceftiofur based on W of species.