Chiral Characterization and Quantification of Deprenyl-N-oxide and Other Deprenyl Metabolites in Rat Urine by Capillary Electrophoresis

Abstract

Chiral capillary electrophoresis has been validated for the quantitative analysis of R-(-)-deprenyl (selegiline) and seven of its metabolites, among them the diastereomeric pair of selegiline-N-oxide in rat urine. Linear calibration curves were obtained over the concentration range: 0.5–100 μM for selegiline, N-desmethylselegiline, methamphetamine, amphetamine, and selegiline-N-oxides, and from 0.1-100 μM for para-hydroxylated derivatives of N-desmethylselegiline, methamphetamine, and amphetamine. The inter and intra-assay precision and accuracy varied by <15% for all analytes at concentrations of 2.5, 10 and 25 μM, and <20% at the lower limit of quantification (0.5 or 0.1 μM). The sample extraction procedure was optimised, and sample recoveries ranged: 80–111% and 74–91% at concentrations of 1 and 10 μM, respectively. The extracted urine samples retained quantitative accuracy for at least 5 days after storage at 4 °C. The validated method was used for in vivo metabolism studies in rats treated with either single or repeated dose of selegiline, or selegiline-N-oxide. Stereoselective N-oxidation of selegiline and rapid urinary excretion of selegiline-N-oxides have been observed. The most abundant metabolites of selegiline were the desalkylated and para-hydoxylated derivatives excreted in both conjugated and unconjugated forms in rat urine.