IMPACT OF TOXYNIL AS ANTIMYCOTOXIN ON THE DISPOSITION KINETICS OF LINCOMYCIN IN BROILER CHICKENS

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 microbiological 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 (Vdss) and the rate of its total body clearance (CLB) 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 (t1/2 ab) was significantly prolonged in toxy-nil medicated birds than in the control ones (0.22 ± 0.016 and 0.163 ±  0.013It, respectively). This associated with a significant decrease in the drug peak plasma concentration (3.54 ± 0.24 i.tg. m1-1) than in the control one (11.56 ± 0.75 [tg.m1-1). 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 conclusion: 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.