ABSTRACT
Pharmacokinetics of lincomycin was studied following single intravenous [I.V.] and oral administrations [20 mg. kg -1 b. wt] in both control and toxy-nil medicated chickens. Lincomycin plasma concentration was determined by microbological assay method. Following I.V. injection, lincomycin plasma concentration versus time curve was best fitted a 2-compartment open model. Toxynil significantly decreased both the distribution and elimination half-lives of lincomycin from 0.28 +/- 0.01 and 1.27 +/- 0.06h in the control group to 0.19 +/- 0.006 and 0.95 +/- 0.04 h in toxy-nil medicated chickens, respectively. The volume of drug distribution at steady state [V dss] and the rate of its total body clearance [CL B] were significantly increased in toxy-nil medicated chickens [1.72 +/- 0.08 L.Kg -1 and 1.95 +/- 0.07 L.Kg -1.h -1 respectively] as compared with that in the control ones [1.38 +/- 0.05 L.Kg -1 and 0.85 +/- 0.03 L.Kg -1.h -1, respectively]. Following oral administration, the absorption half-life [t 1/2 ab]was significantly prolonged in toxy-nil medicated birds than in the control ones [0.22 +/- 0.016 and 0.163 +/- 0.0 13 h, respectively]. This associated with a significant decrease in the drug peak plasma concentration [3.54 +/- 0.24 micro g. ml -1] than in the control one [11.56 +/- 0.75 micro g.ml -l]. The systemic bioavailability [F] was significantly decreased from 73.25 +/- 5.08% in the control group to 38.25 +/- 2.89% in toxy-nil medicated one. In concomitant administration of lincomycin and toxy-nil in broiler chickens should be hindered, as the interaction between both significantly reduces lincomycin oral absorption and enhance its elimination which consequently decreases its therapeutic efficacy