Development and validation of a liquid chromatography-mass spectrometric method for the determination of DPC 423, an antithrombotic agent, in rat and dog plasma

Improved oral bioavailability of novel antithrombotic S002-333 via chitosan coated liposomes: a pharmacokinetic assessment

S002-333, a novel anti-thrombotic agent, exhibits excellent platelet mediated antithrombotic action and subsequently has no effect on the coagulation cascade.

Quantification of phytochelatins in plants by reversed-phase HPLC–ESI–MS–MS

An on-line HPLC-ESI-MS-MS method has been developed for determination of glutathione and phytochelatins (PC) in plant tissues. For sample pretreatment, dithiothreitol (DTT) must be added at the very beginning, as an anti-oxidant. Optimization of instrumental conditions i.e. composition of HPLC mobile phase, ionization efficiency of the electrospray interface, and MS-MS detection in the multiple ion-monitoring mode, are the central aspects of this work. A polystyrene-packed column was found to be superior to a standard silica-packed reversed-phase column. A concave quadratic gradient of ammonium formate buffer and acetonitrile was found to be optimum. The limits of quantitation were 0.2 micromol kg(-1) plant tissue for glutathione and PC. The method has been applied to analysis of tissue samples from Vicia faba grown in Cd-containing nutrient solutions.

A liquid chromatographic-tandem mass spectrometric method for the determination of YM466, a novel Factor Xa inhibitor, in rat plasma

A sensitive and selective method for the determination of YM466, a novel Factor Xa inhibitor, in rat plasma was developed and validated using liquid chromatography-mass spectrometry with electrospray ionization. Plasma samples were pretreated by solid-phase extraction and chromatographed on a C18 column (75 mm x 4.6 mm i.d.) with a mobile phase consisting of 0.1% formic acid-methanol (70:30 (v/v)), and detected using selected reaction monitoring in the positive-ion mode. The lower limit of quantification was 0.4 ng/ml, and good precision and accuracy were achieved. The validated method allowed analysis of samples for the determination of pharmacokinetic profiles of YM466 in rats.

Matrix effects during analysis of plasma samples by electrospray and atmospheric pressure chemical ionization mass spectrometry: practical approaches to their elimination

Some cases of occurrence of matrix effects (mostly ion suppression) in protein-precipitated plasma samples, and their influence on the validity of plasma concentrations and pharmacokinetic parameters, are discussed. The comparison of matrix effects using either electrospray (TurboIonspray, TISP) or atmospheric pressure chemical ionization (APCI) indicated that APCI is less prone to matrix effects. Nevertheless, TISP is usually the first choice of ionization technique since unknown thermally labile metabolites might be present in the plasma samples causing erroneous results. A high impact of ion suppression on the plasma concentrations after intravenous (i.v.) administration was found, depending on the drug formulation (vehicle). Since ion suppression caused significantly lower plasma concentrations (by a factor of up to 5.5) after i.v. dosing, the area under the curve (AUC) was underestimated and the plasma clearance was consequently erroneously high, with an impact on drug candidate selection. By simple stepwise dilution (e.g. 10-fold and 50-fold) of the supernatant of protein-precipitated plasma samples, including all calibration and quality control samples, the matrix effects were recognized and eliminated.