Development and validation of an UPLC-MS/MS assay for quantitative analysis of the ghrelin receptor inverse agonist PF-5190457 in human or rat plasma and rat brain

PF-5190457 is a ghrelin receptor inverse agonist that is currently undergoing clinical development for the treatment of alcoholism. Our aim was to develop and validate a simple and sensitive assay for quantitative analysis of PF-5190457 in human or rat plasma and rat brain using liquid chromatography-tandem mass spectrometry. The analyte and stable isotope internal standard were extracted from 50 μL plasma or rat brain homogenate by protein precipitation using 0.1% formic acid in acetonitrile. Chromatography was carried on an Acquity UPLC BEH C18 (2.1 mm X 50 mm) with 1.7 μm particle size and 130Å pore size. Flow rate was 0.5 mL/min and total chromatographic run time was 2.2 minutes. Mobile phase consisted of gradient mixture of water: acetonitrile 95:5% (v/v) containing 0.1% formic acid (Solvent A), and 100% acetonitrile containing 0.1% formic acid (Solvent B). Multiple reaction monitoring was carried out in positive electro-spray ionization mode using m/z 513.35 → 209.30 for PF-5190457 and m/z 518.47 → 214.43 for the internal standard. The recovery ranged from 102-118% with CV less than 6% for all matrices. The calibration curves for all matrices were linear over the studied concentration range (R(2) ≥ 0.998, n = 3). Lower limit of quantification was 1 ng/mL in rat or human plasma and 0.75 ng/g in rat brain. Intra- and inter-run mean percent accuracy were between 85–115% and percent imprecision was ≤ 15%. The assays were successfully utilized to measure the concentration of PF-5190457 in pre-clinical and clinical pharmacology studies of the compound

Minimally invasive endodontics: challenging prevailing paradigms.

The primary goal of endodontic therapy is the long-term retention of a functional tooth by preventing or treating apical periodontitis. However, there are many other factors that impact endodontic outcomes such as the quality of the restoration and structural integrity of the tooth after root canal preparation. Contemporary research efforts are currently directed to better understanding dentin behaviour and structure during aging and function. An alternative approach is to minimise structural changes during root canal therapy, which may result in a new strategy that can be labelled \u27minimally invasive endodontics\u27. This review addresses current clinical and laboratory data to provide an overview of this new endodontic paradigm