KINETIC DISPOSITION, SYSTEMIC BIOAVAILABILITY AND TISSUE DISTRIBUTIONOF APRAMYCIN IN BROILER-CHICKENS

Apramycin was administered to chickens orally, intramuscularly and int ravenously to determine blood concentration, kinetic behaviour, bioava ilability and tissue residues. Single doses of apramycin at the rate o f 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 (t1/2((ab.))) of 0.10 and 0.19 hours and an elim ination half life (t1/2((beta))) of 1.22 and 2.31 hours respectively. The systemic bioavailability was 2.0 and 58 per cent after intracrop a nd i.m. administration, respectively, indicating poor absorption of th e drug when given orally. Following i.v. injection, the kinetics of ap ramycin was described by a two-compartment open model with a (t1/2((al pha))) of 1.5 hours, (t1/2((beta))) of 2.1 hours, V-d(ss) (volume of d istribution) of 4.82 litre kg(-1) and Cl-(B) (total body clearance) of 1.88 litre kg(-1) hour(-1). The serum protein-binding of apramycin wa s 26 per cent. The highest tissue concentrations of apramycin were pre sent in the kidneys and liver. No apramycin residues were detected in tissues after six hours except in the liver and kidneys following intr acrop dosing and kidneys following i.m. administration.