Determination of bupropion hydrochloride in rat plasma by LC-MS/MS and Its application to pharmacokinetic study

A selective and sensitive liquid chromatography-tandem mass spectrometry method was developed and validated for quantitation of bupropion hydrochloride in rat plasma using triazolam as an internal standard. Chromatographic separation was achieved on a SB-C18 column at 30 °C, with 50: 50 (v/v) acetonitrile-0.1 % formic acid in water as mobile phase. The flow rate was 0.3 mL/min. The determination of bupropion was performed in MRM mode, m/z 239.9 → 183.7 for bupropion and m/z 343.0 → 308.0 for triazolam (IS) and positive ion electrospray ionization interface. Calibration curve was linear over range of 1.2 to 480 ng/mL. The intra- and inter-run relative standard deviations of the assay were less than 10 %. The mean absolute recoveries determined at the concentrations of 2.4, 48 and 360 ng/mLwere 91.00%, 92.06%, 91.71%, respectively. The validated method is successfully used to analyze the drug in samples of rat plasma for pharmacokinetic study.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Case Report: A novel heterozygous nonsense mutation in KRIT1 cause hereditary cerebral cavernous malformation

Cerebral cavernous malformation (CCM) is a vascular malformation of the central nervous system and mainly characterized by enlarged capillary cavities without intervening brain parenchyma. Genetic studies have identified three disease-causing genes (CCM1/KRIT1, CCM2/MGC4607 and CCM3/PDCD10) responsible for CCM. Here, we characterized a four-generation family diagnosed with CCM and identified a novel heterozygous mutation c.1159C>T, p.Q387X in KRIT1 gene by whole exome sequencing and Sanger sequencing. The Q387X mutation resulted in premature termination of KRIT1 protein, which was predicted to be deleterious by the ACMG/AMP 2015 guideline. Our results provide novel genetic evidence support that KRIT1 mutations cause CCM, and are helpful to the treatment and genetic diagnosis of CCM

Determination of bupropion hydrochloride in rat plasma by LC-MS/MS and Its application to pharmacokinetic study

A selective and sensitive liquid chromatography-tandem mass spectrometry method was developed and validated for quantitation of bupropion hydrochloride in rat plasma using triazolam as an internal standard. Chromatographic separation was achieved on a SB-C18 column at 30 °C, with 50: 50 (v/v) acetonitrile-0.1 % formic acid in water as mobile phase. The flow rate was 0.3 mL/min. The determination of bupropion was performed in MRM mode, m/z 239.9 → 183.7 for bupropion and m/z 343.0 → 308.0 for triazolam (IS) and positive ion electrospray ionization interface. Calibration curve was linear over range of 1.2 to 480 ng/mL. The intra- and inter-run relative standard deviations of the assay were less than 10 %. The mean absolute recoveries determined at the concentrations of 2.4, 48 and 360 ng/mLwere 91.00%, 92.06%, 91.71%, respectively. The validated method is successfully used to analyze the drug in samples of rat plasma for pharmacokinetic study.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Determination of troxerutin in rabbit plasma by LC-ESI-MS and its application to a pharmacokinetic study

A sensitive and selective liquid chromatography/electrospray mass spectrometry (LC-ESIMS) method for determination of troxerutin in rabbit plasma was developed. After addition of paeoniflorin as internal standard (IS), protein precipitation by methanol: acetonitrile (3:1, v/v) was used as sample preparation. Chromatographic separation was achieved on an Allure (TM) PFP Propyl (2.1 mm × 100 mm, 5 μm) column with methanol-water as mobile phase with gradient elution. Electrospray ionization (ESI) source was applied and operated in positive ion mode; selected ion monitoring (SIM) mode was used to quantification using target fragment ions m/z 765 for troxerutin and m/z 503 for the IS. Calibration plots were linear over the range of 10-5000 ng/mL for troxerutin in rabbit plasma. Lower limit of quantitation (LLOQ) for troxerutin was 10 ng/mL. Mean recovery of troxerutin from plasma was in the range 92.6-98.1 %. RSD of intra-day and inter-day precision were both less than 11 %. This method is simple and sensitive enough to be used in pharmacokinetic research for determination of troxerutin in rabbit plasma.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Determination of sulpiride in rabbit plasma by LC-ESI-MS and its application to a pharmacokinetic study

A sensitive and selective liquid chromatography-mass spectrometry (LC-MS) method for determination of sulpiride in rabbit plasma was developed and validated. The analyte and internal standard (IS) were extracted from plasma by liquid-liquid extraction using ethyl acetate, and chromatography involved Agilent Extend-C18 column (2.1 mm x 50 mm, 3.5 μm) using 0.2 % formic acid in water and acetonitrile (60: 40, v/v) as a mobile phase. Detection involved positive ion mode electrospray ionization (ESI), and selective ion monitoring (SIM) mode was used for quantification of target fragmentions m/z 342.0 for sulpiride and m/z 294.8 for estazolam (internal standard, IS). The assay was linear over the range of 10-2000 ng/mL for sulpiride, with a lower limit of quantitation (LLOQ) of 10 ng/mL for sulpiride. Intraand inter-day precisions were less than 12 % and the accuracies were in the range of 94.1-108.7 % for sulpiride. This developed method was successfully applied for the determination of sulpiride in rabbit plasma for pharmacokinetic study.Colegio de Farmacéuticos de la Provincia de Buenos Aire

A simple LC-ESI-MS method for the determination of norvancomycin in rat plasma and application to pharmacokinetic study

A simple and sensitive LC-ESI-MS method for determination of norvancomycin in plasma was developed and validated over the concentration range of 20-2,000 ng/mL. After addition of vancomycin as internal standard (IS), protein precipitation with 5 % trichloroacetic acid was employed for the sample preparation. Chromatographic separation was performed on a Zorbax SB-C18 (100 mm×2.1 mm, 3.5 μm) column with 10:90 (v/v) acetonitrile-0.1 % formic acid as mobile phase. The MS data acquisition was accomplished by selective ions monitoring (SIM) mode with positive electrospray ionization (ESI) interface. The limit of quantification (LOQ) was 20 ng/mL. For inter-day and intra-day tests, the precision (RSD) for the entire validation was less than 12 %. The developed method was successfully applied to pharmacokinetic studies of norvancomycin in rats following single intravenous administration dose of 10 mg/Kg.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Determination of meropenem in rabbit plasma by LC-MS/MS

A sensitive and selective liquid chromatography tandem mass spectrometry (LC–MS/MS) method for determination of meropenem in rabbit plasma was developed. After addition of triazolam as internal standard (IS), protein precipitation by acetonitrile was used in sample preparation. Chromatographic separation was achieved on a Restek Allure (TM) PFP Propyl (2.1 mm × 100 mm, 5 μm) column with acetonitrile-0.1 % formic acid as mobile phase with gradient elution. Electrospray ionization (ESI) source was applied and operated in positive ion mode; multiple reaction monitoring (MRM) mode was used to quantification using target fragment ions m/z 384.1 → 339.9 for meropenem and m/z 342.7 → 307.8 for the IS. Calibration plots were linear over the range of 0.1-40 μg/mL for meropenem in plasma. Lower limit of quantification (LLOQ) for meropenem was 0.1 μg/mL. Mean recovery of meropenem from plasma was in the range 85.6 %-96.5 %. CV of intra-day and inter-day precision were both less than 15 %. This method is simple and sensitive enough to be used in pharmacokinetic research for determination of meropenem in rabbit plasma.Colegio de Farmacéuticos de la Provincia de Buenos Aire

The splicing factor DHX38 enables retinal development through safeguarding genome integrity

DEAH-Box Helicase 38 (DHX38) is a pre-mRNA splicing factor and also a disease-causing gene of autosomal recessive retinitis pigmentosa (arRP). The role of DHX38 in the development and maintenance of the retina remains largely unknown. In this study, by using the dhx38 knockout zebrafish model, wedemonstrated that Dhx38 deficiency causes severe differentiation defects and apoptosis of retinal progenitor cells (RPCs) through disrupted mitosis and increased DNA damage. Furthermore, we found a significant accumulation of R-loops in the dhx38-deficient RPCs and human cell lines. Finally, we found that DNA replication stress is the prerequisite for R-loop-induced DNA damage in the DHX38 knockdown cells. Taken together, our study demonstrates a necessary role of DHX38 in the development of retina and reveals a DHX38/R-loop/replication stress/DNA damage regulatory axis that is relatively independent of the known functions of DHX38 in mitosis control