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Dasatinib is a multi-kinase inhibitor that potently inhibits Bcr-Abl, Src family and platelet-derived growth factor receptor kinases. Methotrexate is an antimetabolite and antifolate drug. Clinical trials utilizing a combination of dasatinib and methotrexate in patients with Philadelphia chromosome positive and/or Bcr-Abl positive acute lymphoblastic leukemia are currently ongoing. A need therefore exists to develop a sensitive analytical method for determination of dasatinib and methotrexate in plasma.To estimate methotrexate, dasatinib and its active metabolite N-deshydroxyethyl dasatinib simultaneously using liquid chromatography-electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS) in Wistar rat plasma.The analytes were extracted by using liquid-liquid extraction procedure and separated on a reverse phase C18 column (50 mm×3 mm i.d., 4.6 µ) using methanol: 2 mM ammonium acetate buffer, pH 4.0 as mobile phase at a flow rate 1 mL/min in gradient mode. Selective reaction monitoring was performed using the transitions m/z 455.0>175.0, 488.1 > 401.0, 444.26>401.0, and 271.1>- 155.0 to quantify methotrexate, dasatinib, N-deshydroxyethyl dasatinib and tolbutamide respectively.The method was validated over the concentration range of 1-1 000 ng/mL and the lower limit of quantitation was 1 ng/mL. The recoveries from spiked control samples were > 79% for all analytes and internal standard Intra- and Interday accuracy and precision of validated method were within the acceptable limits of < 15% at all concentration.The quantitation method was successfully applied for simultaneous estimation of methotrexate, dasatinib and N- deshydroxyethyl dasatinib in a pharmacokinetic study in Wistar rats.

Efficacy assessments using a combination of baricitinib and methotrexate necessitate the development of an analytical method for the determination of both drugs in plasma with precision. A high-performance liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the simultaneous determination of baricitinib and methotrexate in rat plasma. Extraction of baricitinib, methotrexate, and tolbutamide (internal standard; IS) from 50 µL of rat plasma was carried out by protein precipitation with methanol. Chromatographic separation of the analytes was performed on the YMC pack ODS AM (150 mm × 4.6 mm, 5 µm) column under gradient conditions with methanol: 2.0 mM ammonium acetate buffer as the mobile phases at a flow rate of 1 mL/min. The precursor ion and product ion transition for both analytes and IS were monitored on a triple quadrupole mass spectrometer, operated with selective reaction monitoring in positive ionization mode. The method was validated over a concentration range of 0.5–250.00 ng/mL for baricitinib and methotrexate. Mean extraction recoveries for baricitinib, methotrexate, and IS of 86.8%, 89.4%, and 91.8% were consistent across low, medium, and high QC levels, respectively. Precision and accuracy at low, medium, and high quality control levels were less than 15% across the analytes. Benchtop, wet, freeze-thaw, and long-term stability were evaluated for both of the analytes. The analytical method was applied to support the pharmacokinetic study of simultaneous estimation of baricitinib and methotrexate in Wistar rats. Assay reproducibility was demonstrated by reanalysis of 18 incurred samples

A sensitive and reliable high-performance liquid chromatography-mass spectrometry (LC-MS/MS) was developed and validated for simultaneous quantification IC87114, roflumilast (RFM), and its active metabolite roflumilast N-oxide (RFN) using tolbutamide as an internal standard. The analytes were extracted by using liquid-liquid extraction and separated on a reverse phase C(18) column (50 mm × 3 mm i.d., 4.6 µ) using methanol: 2 mM ammonium acetate buffer, pH 4.0 as mobile phase at a flow rate 1 mL/min in gradient mode. Selective reaction monitoring was performed using the transitions m/z 398.3 > 145.9, 403.1 >186.9, 419.1 > 187.0 and 271.1 > 155.0 to quantify quantification IC87114, RFM, RFN and tolbutamide, respectively. The method was validated over the concentration range of 0.1-60 ng.mL(-1) for RFM and RFN and 6 to 2980 ng.mL(-1) for IC87114. Intra- and inter-day accuracy and precision of validated method were within the acceptable limits of <15% at all concentrations. Coefficients of correlation (r(2) ) for the calibration curves were >0.99 for all analytes. The quantitation method was successfully applied for simultaneous estimation of IC87114, RFM and RFN in a pharmacokinetic drug-drug interaction study in Wistar rats.