Comparative pharmacokinetics of gentamicin after intravenous, intramuscular, subcutaneous and oral administration in broiler chickens.

摘要

The pharmacokinetics and bioavailability of gentamicin sulphate (5 mg/kg body weight) were studied in 50 female broiler chickens after single intravenous (i.v.), intramuscular (i.m.), subcutaneous (s.c.) and oral administration. Blood samples were collected at time 0 (pretreatment), and at 5, 15 and 30 min and 1, 2, 4, 6, 8, 12, 24 and 48 h after drug administration. Gentamicin concentrations were determined using a microbiological assay and Bacillus subtillis ATCC 6633 as a test organism. The limit of quantification was 0.2 micro g/ml. The plasma concentration-time curves were analysed using non-compartmental methods based on statistical moment theory. Following i.v. administration, the elimination half-life (t1/2 beta ), the mean residence time (MRT), the volume of distribution at steady state (Vss), the volume of distribution (Vd,area) and the total body clearance (ClB) were 2.93+or-0.15 h, 2.08+or-0.12 h, 0.77+or-0.05 L/kg, 1.68+or-0.39 L/kg and 5.06+or-0.21 ml/min per kg, respectively. After i.m. and s.c. dosing, the mean peak plasma concentrations (Cmax) were 11.37+or-0.73 and 16.65+or-1.36 micro g/ml, achieved at a post-injection times (tmax) of 0.55+or-0.05 and 0.75+or-0.08 h, respectively. The t1/2 beta was 2.87+or-0.44 and 3.48+or-0.37 h, respectively after i.m. and s.c. administration. The Vd,area and ClB were 1.49+or-0.21 L/kg and 6.18+or-0.31 ml/min per kg, respectively, after i.m. administration and were 1.43+or-0.19 L/kg and 4.7+or-0.33 ml/min per kg, respectively, after s.c. administration. The absolute bioavailability (F) of gentamicin after i.m. administration was lower (79%) than that after s.c. administration (100%). Substantial differences in the resultant kinetics data were obtained between i.m. and s.c. administration. The in vitro protein binding of gentamicin in chicken plasma was 6.46%..