CORRELATION BETWEEN TISSUE AND PLASMA-CONCENTRATIONS OF OXYTETRACYCLINE IN VEAL CALVES

Mercer et al. (1977) proposed a three-phase experimental design to est ablish withdrawal times, based on plasma pharmacokinetics. This approa ch was the premise of a study in which plasma pharmacokinetics and tis sue depletion data of oxytetracycline after intra-muscular administrat ion were correlated. Correlations between estimated and measured conce ntrations were shown to be significant for kidney tissue (r = .9236, p < .001), liver tissue (r = .9302, p < .01) as well as for muscle tiss ue (r = .9045, p < .001). The data presented support the pharmacokinet ic approach as proposed by Mercer et al. (1977) and demonstrate that t issue elimination rates correlate highly with elimination rates in pla sma. Although generalizations must be applied with caution, this artic le shows that when certain criteria are fulfilled, plasma pharmacokine tics can reliably predict tissue withdrawal times.