Pharmacokinetics of single doses of gentamicin given intravenously and intramuscularly to turkeys

The disposition and absorption kinetics of gentamicin were studied in healthy, mature male and female turkeys (n = 10). Single doses of gentamicin (5 mg/kg) were injected either i.v. or i.m. with a 30-day rest period between each treatment. Baseline and serial venous blood samples (n = 17) were collected from each turkey. Serum concentrations of gentamicin were determined in duplicate for 24 h after each treatment, using radio-immunoassay. Using nonlinear least-square regression methods, the combined data of the i.v. and i.m. treatments were best described by a two-compartment open model. Kinetic analysis of the data after a single i.v. dose provided the following mean values: t1/2 alpha = 0.170 +/- 0.093 h, t1/2 beta = 2.57 +/- 0.79 h, MRT = 3.62 +/- 0.96 h, Vc = 0.090 +/- 0.017 l/kg, Vd(ss) = 0.172 +/- 0.024 l/kg, Vd(area) = 0.190 +/- 0.030 l/kg, and Clt = 49.8 +/- 9.8 ml/h/kg. After a single i.m. dose, the following mean values were determined: MRT = 5.10 +/- 1.73 h, t1/2abs = 0.74 +/- 0.66 h, tlag = 0.07 +/- 0.19 h, Clt/F = 50.7 +/- 12.5 ml/h/kg, Vd(area)/F = 0.193 +/- 0.044 l/kg, and F = 102 +/- 21%. Kinetic calculations made with the single i.m. data predicted that an i.m. injection of gentamicin at the dosage rate of 3 mg/kg q. every 12 h would provide average steady state serum concentrations of 4.93 micrograms/ml.