PHARMACOKINETICS OF AMIKACIN IN AFRICAN ELEPHANTS (LOXODONTA-AFRICANA)

The pharmacokinetics of amikacin in the African elephant (Loxodonta af ricana) 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 m g/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 eli mination half-lives (t1/2) were 4.0 and 3.7 hr, the volumes of distrib ution at steady state were 0.21 and 0.18 L/kg, and total body clearanc es were 41.8 and 40.8 ml/hr/kg. At i.m. doses of 3 and 6 mg/kg, the pe ak concentrations observed ranged from 4.8 to 8.4 mug/ml and 14.2 to 2 1.8 mug/ml, respectively. The time at observed peak concentration was between 1 and 3 hr, and t1/2 ranged from 3.8 to 5.9 hr for the lower d ose and from 3.7 to 6.3 hr for the higher dose. Following the single d ose trials, one elephant was treated with amikacin at a dose of 7 mg/k g i.m. at 24-hr intervals for 21 days, and serum amikacin concentratio ns were determined two to four times on each of 11 days. Mean (+/-SD) peak serum concentration for this elephant was 19.0 +/- 2.8 mug/ml, an d mean serum concentration at 24 hr (trough) was 1.7 +/- 0.4 mug/ml. T here was indication in this one elephant of a mild, reversible renal t ubular insult based on a slight transient elevation in serum creatinin e and the presence of casts in the urine. These changes resolved soon after the end of treatment. These preliminary results suggest that ami kacin administered at 6-8 mg/kg i.m. once every 24 hr would be appropr iate for elephants diagnosed with bacterial infections suspected to be susceptible to amikacin.