Determination of dextromethorphan in rabbit plasma by LC-MS/MS and its application to pharmacokinetic study

A highly sensitive liquid chromatographic tandem mass spectrometric (LC-MS/MS) method for determination of dextromethorphan in rabbit plasma using triazolam as the internal standard (IS) was developed. Plasma samples were extracted with ethyl acetate and separated on a SB-C18 column with a mobile phase of acetonitrile-water 60:40 (v/v) at a flow of 0.3 mL/min. Detection is carried out by multiple reaction monitoring (MRM) on a ion-trap LC-MS/MS system with an electrospray ionization interface. The lower limit of quantification (LLOQ) was 1 ng/mL. After intravenous administration of a single dose of dextromethorphan 2 mg/kg, the main pharmacokinetic parameters were as follows: AUC0→t 636.13 ± 47.13 (ng/mL·h); CL 2.60 ± 0.24 (L/h), Cmax 874 ± 67.16 (ng/mL), Vz 1.58 ± 0.11 (L/kg), T1/2 2.41 ± 0.35 (h), MRT 1.26 ± 0.08 (h).Colegio de Farmacéuticos de la Provincia de Buenos Aire

Development of a UPLC-MS/MS method for the determination of lacosamide and its metabolite and its application to drug-drug interaction

Lacosamide, a third-generation novel antiepileptic drug, was first approved in 2008 as an adjunct to partial seizures. In 2014, the U.S. Food and Drug Administration (FDA) approved it as a single agent for partial seizures. Since epilepsy is a chronic condition, most patients need long-term antiepileptic medicinal products, so it is even more important to consider the drug-drug interactions (DDIs). For the purpose of this experiment, an ultra performance liquid chromatography tandem mass spectrometry (UPLC-MS/MS) assay with accuracy and simplicity was optimized and fully validated for the simultaneous quantitative determination of lacosamide and O-Desmethyl-lacosamide (ODL), and DDIs between lacosamide and nisoldipine in vivo and in vitro was researched. The protein was precipitated with acetonitrile, the analytes were eluted with acetonitrile and a 0.1% formic acid solution in a gradient program, and lacosamide, ODL, and lamotrigine (Internal Standard, IS) were successfully separated by chromatography. The findings of the biological analysis revealed that the lower limit of quantification (LLOQ) for lacosamide in samples was 2 ng/mL and the linearity ranged from 2 to 10000 ng/mL. The LLOQ for ODL was 1 ng/mL, while the linearity range for this substance was 1–1,000 ng/mL. In rat liver microsomes (RLM), the LLOQ of ODL was 80 ng/mL and the linear range was 80–40000 ng/mL. The selectivity, stability, matrix effect and recovery rate were all satisfied with the need of quantitative analysis of samples. Then, the UPLC-MS/MS assay was employed successfully on the interactions of lacosamide and nisoldipine in vivo and in vitro. The half-maximal inhibitory concentration (IC50) was 3.412 μM in RLM, where nisoldipine inhibited the metabolism of lacosamide with a mixture of inhibition mechanism. In rat pharmacokinetic experiments, it was found that nisoldipine could significantly change the pharmacokinetic characteristics of lacosamide, including AUC(0-t), AUC(0-∞), Tmax, CLz/F and Cmax, but had no significant effect on ODL. In summary, the UPLC-MS/MS method could accurately and sensitively quantify lacosamide and ODL, and could be used for the interaction between nisoldipine and lacosamide in vivo and in vitro

Determination of dextromethorphan in rabbit plasma by LC-MS/MS and its application to pharmacokinetic study

A highly sensitive liquid chromatographic tandem mass spectrometric (LC-MS/MS) method for determination of dextromethorphan in rabbit plasma using triazolam as the internal standard (IS) was developed. Plasma samples were extracted with ethyl acetate and separated on a SB-C18 column with a mobile phase of acetonitrile-water 60:40 (v/v) at a flow of 0.3 mL/min. Detection is carried out by multiple reaction monitoring (MRM) on a ion-trap LC-MS/MS system with an electrospray ionization interface. The lower limit of quantification (LLOQ) was 1 ng/mL. After intravenous administration of a single dose of dextromethorphan 2 mg/kg, the main pharmacokinetic parameters were as follows: AUC0→t 636.13 ± 47.13 (ng/mL·h); CL 2.60 ± 0.24 (L/h), Cmax 874 ± 67.16 (ng/mL), Vz 1.58 ± 0.11 (L/kg), T1/2 2.41 ± 0.35 (h), MRT 1.26 ± 0.08 (h).Colegio de Farmacéuticos de la Provincia de Buenos Aire

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 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

Development and Validation of Liquid Chromatography-Mass Spectrometry Method for Determination of Febuxostat in Rat Plasma and its Application

A selective liquid chromatography-mass spectrometry (LC–MS) method for determination of febuxostat in rat plasma was developed and validated. After addition of midazolam as internal standard (IS), protein precipitation by acetonitrile was used as sample preparation, and chromatography involved Agilent SB-C18 column (2.1 x150 mm, 5 μm) using 0.1% formic acid in water and acetonitrile as a mobile phase with gradient elution. Detection involved positive ion mode electrospray ionization (ESI), and selective ion monitoring (SIM) mode was used for quantification of target fragment ions m/z 317 for febuxostat and m/z 326 for midazolam (internal standard, IS). The assay was linear over the range of 10-2000 ng/mL for febuxostat, with a lower limit of quantitation (LLOQ) of 10 ng/mL for febuxostat. Intra- and inter-day RSDs were less than 15% and the accuracies were in the range of 93.8-111.9% for febuxostat. This developed method was successfully applied to determinate of febuxostat in rat plasma for pharmacokinetic study.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Determination of gemcitabine in rabbit plasma by LC-ESI-MS using an Allure PFP propyl column

A sensitive and selective liquid chromatography/electrospray mass spectrometry (LC-ESIMS) method for determination of gemcitabine in rabbit plasma was developed. Chromatographic separation was achieved on a Restek Allure (TM) PFP Propyl (2.1 mm × 100 mm, 5 µm) column with (85: 15, v/v) methanol-water as mobile phase. Electrospray ionization (ESI) source was applied and operated in positive ion mode; selected ion monitoring (SIM) mode was used to quantify gemcitabine using target fragment ions m/z 264. Calibration plots were linear over the range of 5-4000 ng/mL for gemcitabine in plasma. Lower limit of quantitation (LLOQ) for gemcitabine was 5 ng/mL. Mean recovery of gemcitabine from plasma was in the range 91.0-95.5 %. RSD of intra-day and inter-day precision were less than 10 %, respectively. This method is simple, sensitive and fast enough to be used in pharmacokinetic research for determination of gemcitabine in rabbit plasma.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Gradient elution LC-ESI-MS determination of tramadol in rat plasma

A sensitive and simple liquid chromatography/electrospray mass spectrometry (LC-ESI-MS) method for determination of tramadol in rat plasma using one-step protein precipitation was developed. After addition of ketamine as internal standard (IS), protein precipitation by acetonitrile was used as sample preparation. Chromatographic separation was achieved on an SB-C18 (2.1 mm × 50 mm, 3.5 μm) column with methanol-0.1 % formic acid 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 264.0 for tramadol and m/z 237.8 for the IS. Calibration plots were linear over the range of 5-500 ng/mL for tramadol in rat plasma. Lower limit of quantification (LLOQ) for tramadol was 5 ng/mL. Mean recovery of tramadol from plasma was in the range 92.8 %-97.4 %. RSD of intra-day and inter-day precision were both less than 10 %. This method is simple and sensitive enough to be used in pharmacokinetic research for determination of tramadol in rat plasma.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Determination of dezocine in rabbit plasma by liquid chromatography-mass spectrometry and its application

A sensitive and selective liquid chromatography-mass spectrometry (LC–MS) method for determination of dezocine in rabbit plasma was developed and validated. After addition of diazepam as internal standard (IS), liquid–liquid extraction (LLE) was used for sample preparation, and chromatography involved Agilent SB-C18 column (2.1 mmx50 mm, 3.5 um) using 0.1 % formic acid in water and acetonitrile as a mobile phase with gradient elution. Detection involved positive ion mode electrospray ionization (ESI), and selective ion monitoring (SIM) mode was used for quantification of target fragment ions m/z 245.8 for dezocine and m/z 284.8 for diazepam (internal standard, IS). The assay was linear over the range of 5–500 ng/mL for dezocine, with a lower limit of quantitation (LLOQ) of 5 ng/mL for dezocine. Intra- and inter-day precisions were less than 13 % and the accuracies were in the range of 93.1-105.2 % for dezocine. This developed method was successfully applied for the determination of dezocine in rabbit plasma for pharmacokinetic study.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Determination of ramosetron in rat plasma by LC-ESI-MS and its application

A sensitive and simple liquid chromatography/electrospray mass spectrometry (LC-ESI-MS) method for determination of ramosetron in rat plasma using one-step protein precipitation was developed and validated. After addition of midazolam as internal standard (IS), protein precipitation by acetonitrile was used as sample preparation. Chromatographically separation was achieved on an SB-C18 (2.1 mm × 150 mm, 5 μm) column with acetonitrile-0.1 % formic acid as the 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 280 for ramosetron and m/z 326 for the IS. Calibration plots were linear over the range of 10-1000 ng/mL for ramosetron in rat plasma. Lower limit of quantification (LLOQ) for Ramosetron was 10 ng/mL. Mean recovery of ramosetron from plasma was in the range of 88.5-92.8 %. 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 study for determination of ramosetron in rat plasma.Colegio de Farmacéuticos de la Provincia de Buenos Aire