Determination of vincamine in human plasma using automated high-performance liquid chromatography

Measurement and pharmacokinetics of vincamine in rat blood and brain using microdialysis

Vincamine is an alkaloid compound derived from the Vinca minor plant. Since little is known concerning its pharmacokinetics and appropriate analytical method, this study focuses on its pharmacokinetics as well the possible roles of the multidrug transporter P-glycoprotein on its distribution and disposition. We develop a rapid and sensitive method using a microdialysis coupled with liquid chromatography for the concurrent determination of unbound vincamine in rat blood and brain. Microdialysis probes were simultaneously inserted into the jugular vein toward heart and brain hippocampus of male Sprague-Dawley rats for sampling in biological fluids following the administration of vincamine (10 and 30 mg/kg) through the femoral vein. Samples were eluted with a mobile phase containing methanol-1% diethylamine (pH 7.15) in water (75:25, v/v) and the flow rate of the mobile phase was 0.7 ml/min. Pharmacokinetic parameters of vincamine were derived using compartmental model. The decline of protein-unbound vincamine in the hippocampus and blood suggested that there was rapid exchange and equilibration between the peripheral compartment and the central nervous system. In the presence of cyclosporine, unbound vincamine levels in both blood and brain were significantly increased.

Ion-molecule reactions of oxygenated chemical ionization reagents with vincamine

The ion-molecule reactions of ions from acetone, dimethyl ether, 2-methoxyethanol, and vinyl methyl ether with vincamine were investigated. Reactions with dimethyl ether result in [M+13](+) and [M+45](+) products, reactions with 2-methoxyethanol produce [M+13](+) and [M+89](+) ions, and reactions with acetone or vinyl methyl ether ions generate predominantly [M+43](+) ions. Collision-activated dissociation and deuterium labeling experiments allowed speculation about the product structures and mechanisms of dissociation. The methylene substitution process was shown to occur at the hydroxyl oxygen and the phenyl ring of vincamine for dimethyl ether reactions, but the methylene substitution process was not favored at the hydroxyl oxygen for the 2-methoxyethanol reactions, instead favored at the 12 phenyl position. The reaction site is likely different for the 2-methoxyethanol ion due to its capability for secondary hydrogen-bonding interactions. For the [M+45](+) and [M+89](+) ions, evidence suggests that charge-remote fragmentation processes occur from these products. In general, the use of dimethyl ether ions or 2-methoxyethanol ions for ionmolecule reactions prove highly diagnostic for the characterization of vincamine; both molecular weight and structural information are obtained. Limits of detection for vincamine with dimethyl ether chemical ionization via this technique on a benchtop ion trap gas chromatography-tandem mass spectrometer are in the upper parts per trillion range.

Determination of vincamine in human plasma by high-performance liquid chromatography with ultraviolet detection

A simple and rapid high-performance liquid chromatographic method was developed for the determination of vincamine in human plasma. Plasma samples were buffered at pH 9 and after extraction with tert.-butyl methyl ether back-extracted into 0.017 M orthophosphoric acid. Propranolol was used as the internal standard. An aliquot was injected on to a high-performance liquid chromatographic system using a C18 reversed-phase column and an acetonitrile-phosphate buffer containing triethylamine (30:70) as mobile phase. Detection was performed with an ultraviolet detector at 273 nm. The method had good accuracy and precision and the detection limit (0.3 ng/ml with a signal-to-noise ratio of 3:1) allowed the assessment of vincamine concentrations in plasma in pharmacokinetic studies on healthy human volunteers.