Disposition of levetiracetam in healthy adult horses

Abstract

Nine horses received 20 mg/kg of intravenous LEV (LEVIV), 30 mg/kg of intragastric, immediate release LEV (LEVIR) and extended release (LEVER), in a 3-way randomized crossover design. Serum samples were collected over 48 hours, and LEV concentrations determined by immunoassay. Mean  SEM peak concentrations for LEVIR and LEVER were 50.72  3.53 and 53.58  5.31 g/mL, respectively. The mean y-intercept for IV administration was 64.54  8.33 g/mL. The terminal half-life was 6.38  1.97, 7.07  1.93 and 6.22  1.35 hours for LEVIR, LEVER and LEVIV, respectively. Volume of distribution at steady state was 0.63  0.02 L/kg. Total body clearance after IV administration was 1.24  0.10 ml/kg/min. Bioavailability was excellent. Based on this study, a recommended dosing regimen of intravenous or oral LEV, of 32 mg/kg every 12 hours is likely to achieve and maintain therapeutic range with optimal kinetics throughout dosing interval.