Development of a sensitive and rapid method for quantitation of (S)-(â)- and (R)-(+)-metoprolol in human plasma by chiral LCâESIâMS/MS

A selective, sensitive and high throughput liquid chromatography-tandem mass spectrometry (LCâESIâMS/MS) method has been developed for separation and quantification of metoprolol enantiomers on a chiral Lux Amylose-2 (250mmÃ4.6mm, 5μm) column. Solid phase extraction of (S)-(â)- and (R)-(+)-metoprolol and rac-metoprolol-d6 as an internal standard (IS) was achieved on Lichrosep DVB HL cartridges employing 200μL human plasma. Both the analytes were chromatographically separated with a resolution factor of 2.24 using 15mM ammonium acetate in water, pH 5.0 and 0.1% (v/v) diethyl amine in acetonitrile (50:50, v/v) as the mobile phase within 7.0min. The precursorâproduct ion transitions for the enantiomers and IS were monitored in the multiple reaction monitoring and positive ionization mode. The method was validated over the concentration range of 0.500â500ng/mL for both the enantiomers. Matrix effect was assessed by post-column analyte infusion experiment and the mean extraction recovery was greater than 94.0% for both the enantiomers at all quality control levels. The stability of analytes was evaluated in plasma and whole blood under different storage conditions. The method was successfully applied to a clinical study in 14 healthy volunteers after oral administration of 200mg metoprolol tablet under fasting conditions. The assay reproducibility is shown by reanalysis of 68 incurred samples. The suitability of the developed method was assessed in comparison with different chromatographic methods developed for stereoselective analysis of metoprolol in biological matrices. Keywords: S-(â)-metoprolol, R-(+)-metoprolol, Chiral column, Chromatographic separation, LCâESIâMS/MS, Human plasm

Determination of lercanidipine in human plasma by an improved UPLC–MS/MS method for a bioequivalence study

An improved and reliable ultra-performance liquid chromatography/tandem mass spectrometry (UPLC–MS/MS) method has been developed and validated for the determination of lercanidipine in human plasma. Plasma samples with lercanidipine-d3 as an internal standard (IS) were prepared by solid phase extraction on Phenomenex Strata-X cartridges using 100 µL of human plasma. Chromatographic analysis was performed on UPLC BEH C18 (50 mm×2.1 mm, 1.7 µm) column under isocratic conditions. Linear calibration curves were obtained over a wide dynamic concentration range of 0.010–20.0 ng/mL. Matrix effect was assessed by post-column infusion, post-extraction spiking and standard-line slope methods. The mean extraction recovery was >94% for the analyte and IS. Inter-batch and intra-batch precision (% CV) across five quality controls was <5.8%. Bioequivalence study was performed with 36 healthy subjects after oral administration of 10 mg of lercanidipine and the assay reproducibility was evaluated by reanalysis of 133 incurred samples

Determination of cilostazol and its active metabolite 3,4-dehydro cilostazol from small plasma volume by UPLCâMS/MS

A simple, rapid and sensitive ultra performance liquid chromatography-tandem mass spectrometry (UPLCâMS/MS) method has been developed for the simultaneous determination of cilostazol and its pharmacologically active metabolite 3,4-dehydro cilostazol in human plasma using deuterated analogs as internal standards (ISs). Plasma samples were prepared using solid phase extraction and chromatographic separation was performed on UPLC BEH C18 (50 mmÃ2.1 mm, 1.7 µm) column. The method was established over a concentration range of 0.5â1000 ng/mL for cilostazol and 0.5â500 ng/mL for 3,4-dehydro cilostazol. Intra- and inter-batch precision (% CV) and accuracy for the analytes were found within 0.93â1.88 and 98.8â101.7% for cilostazol and 0.91â2.79 and 98.0â102.7% for the metabolite respectively. The assay recovery was within 95â97% for both the analytes and internal standards. The method was successfully applied to support a bioequivalence study of 100 mg cilostazol in 30 healthy subjects. Keywords: Cilostazol, 3,4-dehydro cilostazol, UPLCâMS/MS, Sensitive, High throughpu

A multiparametric organ toxicity predictor for drug discovery

The assessment of major organ toxicities through in silico predictive models plays a crucial role in drug discovery. Computational tools can predict chemical toxicities using the knowledge gained from experimental studies which drastically reduces the attrition rate of compounds during drug discovery and developmental stages. The purpose of in silico predictions for drug leads and anticipating toxicological endpoints of absorption, distribution, metabolism, excretion and toxicity, clinical adverse impacts and metabolism of pharmaceutically active substances has gained widespread acceptance in academia and pharmaceutical industries. With unrestricted accessibility to powerful biomarkers, researchers have an opportunity to contemplate the most accurate predictive scores to evaluate drug's adverse impact on various organs. A multiparametric model involving physico-chemical properties, quantitative structure-activity relationship predictions and docking score was found to be a more reliable predictor for estimating chemical toxicities with potential to reflect atomic-level insights. These in silico models provide informed decisions to carry out in vitro and in vivo studies and subsequently confirms the molecules clues deciphering the cytotoxicity, pharmacokinetics, and pharmacodynamics and organ toxicity properties of compounds. Even though the drugs withdrawn by USFDA at later phases of drug discovery which should have passed all the state-of-the-art experimental approaches and currently acceptable toxicity filters, there is a dire need to interconnect all these molecular key properties to enhance our knowledge and guide in the identification of leads to drug optimization phases. Current computational tools can predict ADMET and organ toxicities based on pharmacophore fingerprint, toxicophores and advanced machine-learning techniques

Morbidity Profile and Functional Outcome of Modified Facial Translocation Approaches for Skull Base Tumors

The primary objective of this study was to evaluate morbidity associated with facial translocation approaches for skull base and results of various technical modifications. Forty consecutive patients who underwent facial translocation approaches for accessing skull base tumors from July 2005 to June 2010 were included in this study. There were 25 patients who underwent standard facial translocation, 4 patients medial mini, and 11 patients underwent extended facial translocation. Thirteen patients had benign disease and 27 patients had malignant disease. Resection was R0 in 36 and R1 in 4 patients. Most patients had acceptable cosmetic results. None of the patients had problems related to occlusion or speech and swallowing. The commonest complication observed was nasal crusting in 16 patients. Grade 2 trismus and exposure of mini plate was seen in three patients. Two patients developed necrosis of translocated bone. Three patients developed palatal fistula before modification of palatal incision. Facial translocation provides a satisfactory access for adequate clearance of skull base tumors with satisfactory aesthetic and functional results. With modifications of the surgical technique and implementation of new surgical tools, the morbidity of facial translocation approaches will continue to decrease

Stability values for targeted TCA intermediates under different conditions.

<p>Stability values for targeted TCA intermediates under different conditions.</p

Body weight gain for mice fed HFD diet and control chow over 8 weeks.

<p>**** p < 0.0001.</p

Representation of the TCA cycle and anaplerotic energy metabolites, showing metabolite levels after HFD (H) and control chow (C) feeding to 8 week-old mice for 8 weeks.

<p>Ordinate axes represent metabolite peak area/IS peak area, except for SLC5A6 expression (top right), where the ordinate represents mRNA expression.</p

Pharmacophore-based virtual screening of catechol-o-methyltransferase (COMT) inhibitors to combat Alzheimer’s disease

<p>Alzheimer’s disease (AD) is one of the most significant neurodegenerative disorders and its symptoms mostly appear in aged people. Catechol-o-methyltransferase (COMT) is one of the known target enzymes responsible for AD. With the use of 23 known inhibitors of COMT, a query has been generated and validated by screening against the database of 1500 decoys to obtain the GH score and enrichment value. The crucial features of the known inhibitors were evaluated by the online ZINC Pharmer to identify new leads from a ZINC database. Five hundred hits were retrieved from ZINC Pharmer and by ADMET (absorption, distribution, metabolism, excretion, and toxicity) filtering by using FAF-Drug-3 and 36 molecules were considered for molecular docking. From the COMT inhibitors, opicapone, fenoldopam, and quercetin were selected, while ZINC63625100_413 ZINC39411941_412, ZINC63234426_254, ZINC63637968_451, and ZINC64019452_303 were chosen for the molecular dynamics simulation analysis having high binding affinity and structural recognition. This study identified the potential COMT inhibitors through pharmacophore-based inhibitor screening leading to a more complete understanding of molecular-level interactions.</p