Pharmacokinetics of gentamicin following single-dose parenteral administration to goats

The disposition kinetics of parenterally administered gentamicin (5 mg kg-1) has been studied in Gaddi goats. The serum concentration-time profile was described by bi-exponential and mono-exponential equations following intravenous (i.v.), intramuscular (i.m.) and subcutaneous (s.c.) administration with elimination half-life values of 0.96 +/- 0.09, 2.37 +/- 0.47 and 3.56 +/- 0.39 h, respectively. The apparent volume of distribution following i.v. administration (Vdarea: 0.26 +/- 0.041 kg-1) reflected limited extracellular distribution of the drug. The bioavailability was higher following i.m. administration (96.3%) compared to s.c. (76.9%). In view of the significantly longer biological half-life and larger area under the curve values, the s.c. route may be preferred. It is concluded that a suitable and practical dosage recommendation for gentamicin in goats would be 3.35 mg kg-1 body weight given s.c. at 12 h intervals.