INFLUENCE OF SUBCHRONIC LEAD INTOXICATION ON THE PHARMACOKINETIC PROFILE OF OXYTETRACYCLINE IN BROILER CHICKENS

The pharmacokinetic profile of oxytetracycline in healthy and experimentally lead intoxicated broiler chickens following its single oral and intravenous administration (10 mg/Kg b. wt) was studied. Tissue distribution and residue - depletion following its oral administration for 5 successive days was investigated. Lead acetate solution was given orally in a subtoxic dose of 4.2 mg/Kg b.wt/day for 8 successive weeks prior to oxytetracyline administration. Oxytetracycline reached its maximum concentration at 1 hr following its oral administration in healthy and lead-intoxicated chickens with a mean serum level of 0.73 and 0.47 ug/ml and absorption half-life (t ) of 9.89
0.5(ab) and 13.08 minutes and elimination half-life (t ) 2.12 and 1.97 hrs, respectively. A short interval between doses of the drug was calculated for intoxicated group as compared with healthy one. Following intravenous injection, oxytetracycline was fitted to follow one compartment model in healthy as well as in intoxicated group with t.
0.5 of 2.18 and 2.56 hrs, volume of distribution (VD) of 9.22 and 8.79 L/Kg and total body clearance of 28.91 and 32.58 mg/Kg/min., respectively. A decreased value for systemic bioavailablity (F%) of the drug was recorded for lead-intoxicated group (54.05%) as compared with healthy one (78.85%) after its oral administration indicating lower extent of drug absorption from intestinal tract of intoxicated chickens than healthy ones. Following oral adminsitration of oxytetracycline (10 mg/Kg b.wt) for 5 successive days, the drug was detected in edible tissues (liver, lung, kidney and muscles) of healthy and intoxicated chickens on the first day after its discontinuation with residual levels lower than 0.25 ppm and completely deplete from tissues after the third and second day in healthy and lead-intoxicated chickens, respectively.