Pharmacokinetic and tissue distribution of doxycycline in broiler chickens pretreated with either: Diclazuril or halofuginone

Following IV injection of doxycycline in a dose of 20 mg kg−1 b.wt., its serum concentration was best fitted in two-compartment open model in chickens fed either on control or on anticoccidials-containing rations. Diclazuril and halofuginone resulted in a significant short distribution half-life (t½α) (7.17 ± 0.39 and 11.88 ± 1.05 min, respectively) and increased total body clearance (Cltot) 0.37 ± 0.024 and 0.295 ± 0.034 L/kg/h, respectively. Following oral dosing the tested drug absorbed with t½ab of 41.38 ± 1.6, 17.48 ± 0.86 and 41.83 ± 1.8 min, respectively and their Cmax values (3.18 ± 0.18, 5.425 ± 0.48 and 0.986 ± 0.037 μg/ml) were attained at 2.07 ± 0.097, 1.403 ± 0.074 and 2.55 ± 0.106 h. For doxycycline alone and in presence of diclazuril and halofuginone, respectively. Systemic bioavailability was 22.64 ± 3.46, 86.74 ± 9.23 and 22.38 ± 3.09%, respectively. Following IM injection t½ab were 9.096 ± 1.34 for doxycycline alone, 16.24 ± 2.21 and 15.6 ± 1.7 min in the presence of diclazuril and halofuginone, respectively. Cmax was 3.10 ± 0.28, 4.63 ± 0.57 and 0.55 ± 0.07 μg/ml reached at 0.8 ± 0.083, 1.13 ± 0.126 and 1.21 ± 0.105 h. For the antibiotic alone, and in presence of either diclazuril and halofuginone, respectively. Systemic bioavailability was 22.41 ± 3.86, 88.97 ± 12.9 and 12.31 ± 0.99% in chickens fed on anticoccidial-free, diclazuril- and halofuginone-containing rations, respectively. Both the tested anticoccidials induced higher doxycycline tissue residues in all tested tissue samples.