Comparative pharmacokinetics of amikacin sulphate in calves and sheep

The pharmacokinetics of amikacin sulphate were investigated in calves and sheep. Five animals of each species were given 7.5 mg kg-1 intravenously and intramuscularly. After intravenous administration the pharmacokinetic parameters significantly different (P less than 0.01) between calves (first value) and sheep (second value), were: the initial concentration (87.05, 146.6 micrograms ml-1), the apparent distribution volume (350, 200 ml kg-1), the area under curve (5512, 11,018 min micrograms ml-1) and the clearance (1.5, 0.7 ml min-1 kg-1). After dosing intramuscularly the peak concentration (23.5, 34.36 micrograms ml-1), the peak time (45, 75 min) and the area under curve (5458, 9191 min micrograms ml-1) were significantly different (P less than 0.01). No significant differences were observed in the terminal halflife values, suggesting that elimination rate was independent of both route of administration and animal species. The drug in aqueous solution showed a good bioavailability in both animal species (about 0.87 in sheep and greater than 0.99 in calves) despite the greater serum concentrations always attained in sheep.