Pharmacokinetics and effects of aminorex in horses

Objective—To investigate the pharmacokinetics and behavioral effects of aminorex administered IV and PO in horses. Animals—7 Thoroughbreds. Procedures—In a cross-over design, aminorex (0.03 mg/kg) was administered IV or PO. Plasma and urinary aminorex concentrations were determined via liquid chromatography– mass spectrometry. Results—Decrease of aminorex from plasma following IV administration was described by a 3-compartment pharmacokinetic model. Median (range) values of α, β, and γ half-lives were 0.04 (0.01 to 0.28), 2.30 (1.23 to 3.09), and 18.82 (8.13 to 46.64) hours, respectively. Total body and renal clearance, the area under the plasma time curve, and initial volume of distribution were 37.26 (28.61 to 56.24) mL·min/kg, 1.25 (0.85 to 2.05) mL·min/kg, 13.39 (8.82 to 17.37) ng·h/mL, and 1.44 (0.10 to 3.64) L/kg, respectively. Oral administration was described by a 2-compartment model with first-order absorption, elimination from the central compartment, and distribution into peripheral compartment...