PHARMACOKINETICS OF AMIKACIN IN AFRICAN ELEPHANTS {LOXODONTA AFRICANA)

The pharmacokinetics of amikacin in the African elephant (Loxodonta africana) were determined after i.v. and i.m. administration. Two adult females were given single i.v. injections of amikacin at a dose of 8 mg/kg. Trials using 3 mg/kg and 6 mg/kg i.m. were conducted with three adult females. Serum concentrations of amikacin were measured serially over a 24-49-hr period. After i.v. administration of 8 mg/kg, the elimination half-lives (t J were 4.0 and 3.7 hr, the volumes of distribution at steady state were 0.21 and 0.18 L/kg, and total body clearances were 41.8 and 40.8 ml/hr/kg. At i.m. doses of 3 and 6 mg/kg, the peak concentrations observed ranged from 4.8 to 8.4 Mg/ml and 14.2 to 21.8 ?tg/ml, respectively. The time at observed peak concentration was between 1 and 3 hr, and tV2 ranged from 3.8 to 5.9 hr for the lower dose and from 3.7 to 6.3 hr for the higher dose. Following the single dose trials, one elephant was treated with amikacin at a dose of 7 mg/kg i.m. at 24-hr intervals for 21 days, and serum amikacin concentrations were determined two to four times on each of 11 days. Mean (?SD) peak serum concentration for this elephant was 19.0 ? 2.8 Mg/ml, and mean serum concentration at 24 hr (trough) was 1.7 ? 0.4 ?eg/ml. There was indication in this one elephant of a mild, reversible renal tubular insult based on a slight transient elevation in serum creatinine and the presence of casts in the urine. These changes resolved soon after the end of treatment. These preliminary results suggest that amikacin administered at 6-8 mg/ kg i.m. once every 24 hr would be appropriate for elephants diagnosed with bacterial infections suspected to be susceptible to amikacin.