Kinetic disposition, systemic bioavailability and tissue distribution of apramycin in broiler chickens

Apramycin was administered to chickens orally, intramuscularly and intravenously to determine blood concentration, kinetic behaviour, bioavailability and tissue residues. Single doses of apramycin at the rate of 75 mg kg −1 body weight were given to broiler chickens by intracrop, i.m. and i.v. routes. The highest serum concentrations of apramycin were reached 0·20 and 0·76 hours after the oral and i.m. doses with an absorption half-life ( t 1 2 (ab.) ) of 0·10 and 0·19 hours and an elimination half life ( t 1 2 (β) ) of 1·22 and 2·31 hours respectively. The systemic bioavailability was 2·0 and 58 per cent after intracrop and i.m. administration, respectively, indicating poor absorption of the drug when given orally. Following i.v. injection, the kinetics of apramycin was described by a two-compartment open model with a ( t 1 2 (α) ) of 1·5 hours, ( t 1 2 (β) ) of 2·1 hours, V d(ss) (volume of distribution) of 4·82 litre kg −1 and C1 (B) (total body clearance) of 1·88 litre kg −1 hour −1. The serum protein-binding of apramycin was 26 per cent. The highest tissue concentrations of apramycin were present in the kidneys and liver. No apramycin residues were detected in tissues after six hours except in the liver and kidneys following intracrop dosing and kidneys following i.m. administration.