Pharmacokinetics of amikacin in lactating goats.

The pharmacokinetics of amikacin was studied in five lactating goats after single intravenous and intramuscular administrations of 7.5 mg kg-1 body weight. After intravenous injection, the plasma concentration-time curve of amikacin was characteristic of a two-compartment open model with a distribution half-life of 11.03 min and an elimination half-life of 114.81 min. The mean residence time was 142.96 min and the volume of the central compartment was 0.061 kg-1. Following intramuscular injection, amikacin was rapidly absorbed with an absorption half-life of 20.39 min. The peak plasma concentration was 34.48 micrograms ml-1 and was attained at 62.15 min. The elimination half-life of amikacin after intramuscular administration was 122.86 min and the corresponding mean residence time was 205.51 min. The systemic bioavailability of amikacin after intramuscular administration was 98.27%. Amikacin was not bound to plasma and milk proteins in vitro. Amikacin was detected only at low concentrations in the goat's milk 2-6 h after intravenous and intramuscular injections. Amikacin urine concentrations were much higher than those of plasma. Thus, amikacin is likely to be efficacious in the eradication of many Gram-negative urinary tract pathogens.