Pharmacokinetics of clarithromycin after single intravenous and intracrop bolus administrations to broiler chickens

The pharmacokinetics of clarithromycin at a dose of 7.5 mg/kg body weight was evaluated after single intravenous (i.v.) and intracrop (i.c.) bolus administrations in broilers. An HPLC assay using pure clarithromycin base as a standard was used to measure its concentrations in plasma. Following an i.v. bolus injection, the plasma concentration-time curves of clarithromycin were best represented by two-compartment open models. The drug was rapidly distributed and moderately eliminated with half-lives of distribution (t_1/2α) and elimination (t_1/2β) of 0.38 and 4.58 h, respectively. The volume of distribution was large with (V_dss) value of 6.89 L. The total body clearance (Cl_B) was 1.2 L/h. After i.c. bolus administration of the same dose, clarithromycin was moderately absorbed in broilers with an intermediate absorption half-life (T_½ab) of 0.72 h with peak plasma concentration (C_max) of 1.69 μg/ml attained at 1.7 h (T_max) and systemic bioavailability of 66.54%. The elimination half-life following i.c. administration was 2.11 h. The extent of plasma protein binding percent was 52%. The study recommends the use of clarithromycin in broilers because of its good pharmacokinetic profile indicated by good absorption, bioavailability and plasma concentrations ≥ MICs of many sensitive microorganisms.