Bionalytical validation study for the determination of unbound ambrisentan in human plasma using rapid equilibrium dialysis followed by ultra performance liquid chromatography coupled to mass spectrometry.

Ambrisentan is a highly selective endothelin-1 type A receptor antagonist indicated for use in the treatment of pulmonary hypertension. In this study an assay was developed and validated for the quantification of total and unbound (free) concentrations of ambrisentan in human plasma. Plasma samples were dialysed against phosphate buffered saline in a rapid equilibrium dialysis device to obtain dialysate and plasma for unbound and total ambrisentan, respectively.

Evaluation of human plasma sample preparation protocols for untargeted metabolic profiles analyzed by UHPLC-ESI-TOF-MS.

Eight human plasma preparation protocols were evaluated for their suitability for metabolomic studies by ultra-high-performance liquid chromatography coupled with electrospray ionization time-of-flight mass spectrometry: organic solvent protein precipitation (PPT) with either methanol or acetonitrile in 2:1 and 3:1 (v/v) ratios with plasma; solid-phase extraction (SPE) using C18 or HybridSPE cartridges; and a combination of PPT and SPE C18 cartridges and microextraction by packed sorbent. A study design in which the order of injection of the samples was not randomized is presented. The analyses were conducted in a BEH C18 column (1.

LC-MS/MS method for the determination of several drugs used in combined cardiovascular therapy in human plasma.

A simple, fast and validated method is reported for the simultaneous analysis, in human plasma, of several drugs usually combined in cardiovascular therapy (atenolol, bisoprolol, hydrochlorothiazide, chlorthalidone, salicylic acid, enalapril and its active metabolite enalaprilat, valsartan and fluvastatin) using high performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) with electrospray ionization (ESI), working in multiple reaction monitoring mode (MRM). Separation of analytes and internal standard (pravastatin) was performed on a Luna C18(2) (150mm×4.6mm, 3μm) column using a gradient elution mode with a run time of 15min.