Abstract
Disposition of amikacin following intracardiac (IC) and intramuscular (IM) administration in twelve ball pythons (Python regius) at 25' C and 37' C was studied. Blood samples were collected by cardiocentesis at 0, 15, 30, 60, 90, 360, 720, 1,440, 2,880, 4,320, 5,760, and 8,640 minutes after administration of amikacin. A 28-day washout period occurred between each study. Drug concentration versus time curves following IC administration at both temperatures best fit a two-compartment open model. For snakes housed at 37'C the Co, or extrapolated time zero concentration, was 17.64+3.52 ug/ml with a median elimination half-life of 6,604.5 minutes (4.5 days). The Cmax was 11.98+1.67 ug/ml and 13.87 + 2.61 ug/ml for snakes housed at 25'C and 37'C respectively. There were no significant pharmacokinetic differences among the snakes housed at 25'C and 37'C. Model independent parameters were area under the curve, 69,900+0.011 ug-min/ml; apparent volume of distribution at steady state, 410+106 ml/kg; clearance, 0.0360︢.009 ml/min/kg and mean residence time, 3,530+273.7 minutes. Mean serum amikacin concentrations did not reach the recommended peak concentrations for mammals (25 ug/ml). In addition, the amikacin serum concentration had not fallen below the recommended trough concentrations (2 ug/ml) by 8,640 minutes or 6 days. However, snakes that received amikacin either IC or IM and housed at 25' C or 37' C, the serum amikacin concentrations were above the MIC50 of selected gram-negative bacteria for up to 6 days. Based on results of this study, the mean amikacin dose (3.48 mg/kg) administered IM to ball pythons should produce serum concentrations above the MIC50 for most bacteria. In this study, it would have taken another half-life, or 4.5 days, before trough concentrations of 2 ug/ml were achieved.
Johnson, James Harvey (1995). Amikacin pharmacokinetics and the effects of ambient temperature on the dosage regimen in ball pythons (Python reguis). Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -1995 -THESIS -J637.