Effect of Tinospora cordifolia aqua-alcoholic extract on pharmacokinetic of Glibenclamide in rat: An herb-drug interaction study.

Tinospora cordifolia (TC) has been used as a complimentary/alternative medicine against diabetes. Considering its potential to modulate metabolic enzymes, Tinospora cordifolia extract (TCE) may influence the metabolism of the antidiabeic drug Glibenclamide following co-administration. Accordingly, this work was undertaken to evaluate impact of TCE on fate of Glibenclamide. Activity of clinically important Cytochrome P450 isoenzymes were inhibited in the order of CYP2C9 > CYP2D6 > CYP2C19 > CYP1A2 > CYP3A4. Formations of metabolites were inhibited with increasing concentration of TCE in both rat and human liver microsomes. TCE was co- administered in three different groups (0, 100 and 400 mg/kg) with Glibenclamide at 1 mg/kg dose to observe the alteration in pharmacokinetic parameters of Glibenclamide. The rats were pretreated with 0 (vehicle), 100 and 400 mg/kg dose of TCE b.i.d for 14 days and on the 14th day all three groups were administered with 1 mg/kg Glibenclamide. Pharmacokinetic parameters were analyzed based on plasma concentrations of Glibenclamide from all the groups by LC-HRMS methods using Glipizide as an internal standard. At 400 mg/kg dose, a marked increase in the bio availability of Glibenclamide was observed with a significant delay of Tmax and suppression of clearance.

Development and validation of an enantioselective LC-MS/MS method to quantify enantiomers of (±)-TAK-700 in rat plasma: lack of in vivo inversion of (+)-TAK-700 (Orteronel) to its antipode.

A highly sensitive, specific and enantioselective assay has been developed and validated for the estimation of TAK-700 enantiomers [(+)-TAK-700 and (-)-TAK-700] in rat plasma on LC-MS/MS-ESI in the positive-ion mode. Liquid-liquid extraction was used to extract (±)-TAK-700 enantiomers and IS (phenacetin) from rat plasma. TAK-700 enantiomers were separated using methanol and 5 mm ammonium acetate (80:20, v/v) at a flow rate of 0.7 mL/min on a Chiralcel OJ-RH column. The total run time was 7.0 min and the elution of (+)-TAK-700, (-)-TAK-700 and IS occurred at 3.71, 4.45 and 4.33 min, respectively. The MS/MS ion transitions monitored were m/z 308.2 → 95.0 for TAK-700 and m/z 180.2 → 110.1 for IS. The standard curves for TAK-700 enantiomers were linear (r(2) > 0.998) in the concentration range 2.01-2015 ng/mL for each enantiomer. The inter- and intra-day precisions were in the ranges 3.74-7.61 and 2.06-8.71% and 3.59-9.00 and 2.32-11.0% for (+)-TAK-700 and (-)-TAK-700, respectively. Both the enantiomers were found to be stable in a battery of stability studies. This novel method was applied to the study of stereoselective oral pharmacokinetics of (+)-TAK-700 and it was unequivocally demonstrated that (+)-TAK-700 does not undergo chiral inversion to its antipode in vivo.

Development and validation of a highly sensitive method for the determination of abiraterone in rat and human plasma by LC-MS/MS-ESI: application to a pharmacokinetic study.

A highly sensitive, rapid assay method has been developed and validated for the estimation of abiraterone (ART) in rat and human plasma with liquid chromatography coupled to tandem mass spectrometry and electrospray ionization in the positive-ion mode. The assay procedure involves extraction of ART and phenacetin (internal standard, IS) from rat and human plasma with a simple protein precipitation extraction process. Chromatographic separation was achieved using an isocratic mobile (10 mm ammonium acetate:acetonitrile, 10:90, v/v) at a flow-rate of 0.70 mL/min on an Atlantis dC(18) column maintained at 40 °C with a total run time of 3.5 min. The MS/MS ion transitions monitored were 350.3 → 156.0 for ART and 180.2 → 110.1 for IS. Method validation was performed as per FDA guidelines and the results met the acceptance criteria. The lower limit of quantitation achieved was 0.20 ng/mL and the linearity range extended from 0.20 to 201 ng/mL. The intra- and inter-day precisions were in the ranges 2.39-10.4 and 4.84-9.53% in rat plasma and 3.82-10.8 and 6.97-8.94% in human plasma.

A strategy for extending the applicability of a validated plasma calibration curve to quantitative measurements in multiple tissue homogenate samples: a case study from a rat tissue distribution study of JI-101, a triple kinase inhibitor.

A general practice in bioanalysis is that, whatever the biological matrix the analyte is being quantified in, the validation is performed in the same matrix as per regulatory guidelines. In this paper, we are presenting the applicability of a validated LC-MS/MS method in rat plasma for JI-101, to estimate the concentrations of JI-101 in various tissues that were harvested in a rat tissue distribution study. A simple protein precipitation technique was used to extract JI-101 and internal standard from the tissue homogenates. The recovery of JI-101 in all the matrices was found to be >70%. Chromatographic separation was achieved using a binary gradient using mobile phase A (acetonitrile) and B (0.2% formic acid in water) at a flow rate of 0.30 mL/min on a Prodigy ODS column with a total run time of 4.0 min. The MS/MS ion transitions monitored were 466.1 → 265 for JI-101 and 180.1 → 110.1 for internal standard. The linearity range was 5.02-4017 ng/mL. The JI-101 levels were quantifiable in the various tissue samples harvested in this study. Therefore, the use of a previously validated JI-101 assay in plasma circumvented the tedious process of method development/validation in various tissue matrices.

Development and validation of a highly sensitive LC-MS/MS method for simultaneous quantitation of ethionamide and ethionamide sulfoxide in human plasma: application to a human pharmacokinetic study.

A highly sensitive and specific LC-MS/MS method has been developed for simultaneous quantification of ethionamide and ethionamide sulfoxide in human plasma (300 µL) using prothionamide as an internal standard (IS). Solid-phase extraction was used to extract ethionamide, ethionamide sulfoxide and IS from human plasma. The chromatographic separation of ethionamide, ethionamide sulfoxide and IS was achieved with a mobile phase consisting of 0.1% acetic acid : acetonitrile (20:80, v/v) at a flow rate of 0.50 mL/min on a Peerless Basic C(18) column. The total run time was 3.5 min and the elution of ethionamide, ethionamide sulfoxide and IS occurred at 2.50, 2.18 and 2.68 min, respectively. A linear response function was established for the range of concentrations 25.7-6120 ng/mL (r > 0.998) for ethionamide and 50.5-3030 ng/mL (r > 0.998) for ethionamide sulfoxide. The intra- and inter-day precision values for ethionamide and ethionamide sulfoxide met the acceptance as per FDA guidelines. Ethionamide and ethionamide sulfoxide were stable in battery of stability studies, viz. bench-top, autosampler and freeze-thaw cycles. The developed assay was applied to a pharmacokinetic study in humans.

A highly sensitive LC-MS/MS method for the determination of S-raclopride in rat plasma: application to a pharmacokinetic study in rats.

A highly sensitive and rapid assay method has been developed and validated for the estimation of S-(-)-raclopride (S-RCP) in rat plasma with liquid chromatography coupled to tandem mass spectrometry with electrospray ionization in the positive ion mode. The assay procedure involves a simple liquid-liquid extraction technique for extraction of S-RCP and phenacetin (internal standard, IS) from rat plasma. Chromatographic separation was achieved with 0.2% formic acid : acetonitrile (80:20, v/v) at a flow rate of 0.30 mL/min on a Phenomenex Prodigy C(18) column with a total run time of 4.5 min. The MS/MS ion transitions monitored were 347.2 → 112.1 for S-RCP and 180.1 → 110.1 for IS. Method validation and pre-clinical sample analysis were performed as per FDA guidelines and the results met the acceptance criteria. The lower limit of quantitation achieved was 0.05 ng/mL and the linearity range was extended from 0.05 to 152 ng/mL in rat plasma. The intra-day and inter-day precisions were 0.23-10.5 and 3.74-7.29%, respectively. This novel method was applied to a pharmacokinetic study of S-RCP in rats.