Quantitative liquid chromatographic and tandem mass spectrometric determination of vitamin D3 in human serum with derivatization: a comparison of in-tube LLE, 96-well plate LLE and in-tip SPME.

Sensitive and selective methods based on high performance liquid chromatography (HPLC) with tandem mass spectrometric (MS/MS) detection were developed for the determination of vitamin D(3) in human serum. Derivatization of vitamin D(3) and its stable isotope labeled internal standard provided highly sensitive quantification and selective detection from endogenous compounds. Samples were prepared using the in-tube liquid-liquid extraction (LLE), 96-well plate LLE, and in-tip solid phase micro-extraction (SPME) in 96-well format.

Bioavailability of alendronate and vitamin D(3) in an alendronate/vitamin D(3) combination tablet.

These studies were designed to demonstrate that the alendronate (ALN) component of an ALN/vitamin D(3) combination tablet was bioequivalent to the 70-mg ALN tablet and that the pharmacokinetic parameters of vitamin D(3) were similar with or without ALN. These were open-label, randomized, 2-part, 2-period, crossover studies. In part I, participants received either a single combination tablet or ALN 70 mg.

Determination of sitagliptinin human plasma using protein precipitation and tandem mass spectrometry.

A simple offline LC-MS/MS method for the quantification of sitagliptin in human plasma is described. Samples are prepared using protein precipitation. Filtration of the supernatants through a Hybrid-SPE-PPT plate was found to be necessary to reduce ionization suppression caused by co-elution of phospholipids with sitagliptin.

Lack of effect of aprepitant or its prodrug fosaprepitant on QTc intervals in healthy subjects.

Background: A single 115-mg dose of fosaprepitant, the IV prodrug of the NK(1) receptor antagonist aprepitant, is bioequivalent to a 125-mg dose of oral aprepitant. Thus far, fosaprepitant/aprepitant has not shown a meaningful effect on QTc intervals; in this study, we sought to confirm these findings.

Methods: This double-blind, active-controlled, randomized, three-treatment, three-period, crossover study in healthy young subjects evaluated the effect of a 200-mg dose of fosaprepitant on QTc prolongation.

Tolerability of fosaprepitant and bioequivalency to aprepitant in healthy subjects.

Fosaprepitant is an intravenous formulation of aprepitant, an oral NK1 antagonist used to prevent chemotherapy-induced nausea and vomiting. This randomized study was designed to evaluate fosaprepitant in polysorbate 80 vehicle for tolerability and bioequivalency to aprepitant. Tolerability was assessed by physical and laboratory examinations and adverse events.