No abstract

A rapid, simple, sensitive and selective LC-MS/MS method was developed and validated for simultaneous quantification of montelukast (MT) and fexofenadine (FF) in human plasma (200 μL) using montelukast-d6 (MT-d6 ) and fexofenadine-d10 (FF-d10 ), respectively as an internal standard (IS) as per the US Food and Drug Administration guidelines. The chromatographic resolution was achieved on a Chromolith RP18e column using an isocratic mobile phase consisting of 20 mm ammonium formate-acetonitrile (20:80, v/v) at flow rate of 1.2 mL/min. The LC-MS/MS was operated under the multiple-reaction monitoring mode using electrospray ionization. The total run time of analysis was 4 min and elution of MT, FF, MT-d6 and FF-d10 occurred at 2.5, 1.2, 2.4 and 1.2 min, respectively. The standard curve found to be linear in the range 2.00-1000 ng/mL with a coefficient of correlation of ≥0.99 for both the drugs. The intra- and inter-day accuracy and precision values for MT and FF met the acceptance as per FDA guidelines. MT and FF were found to be stable in a battery of stability studies viz., bench-top, auto-sampler and repeated freeze-thaw cycles. The validated assay was applied to an oral bioequivalence study in humans.

The method was successfully applied to a bioequivalence study in 34 healthy human subjects. The assay reproducibility was confirmed by reanalysis of 130 subject samples.

A simple, precise and rapid liquid chromatography–tandem mass spectrometry (LC–MS/MS) method has been developed and validated for the simultaneous determination of oseltamivir and oseltamivir carboxylate, a neuraminidase inhibitor, using their deuterated analogs as internal standards (ISs). The method involved solid phase extraction of the analytes and ISs from 200 μL human plasma with no reconstitution and drying steps. The chromatographic separation was achieved on a Symmetry C18 (100 mm×4.6 mm, 5 μm) column using 10 mM ammonium formate and acetonitrile (30:70, v/v) as the mobile phase in a run time of 2.0 min. Quantitation of analytes and ISs were done by multiple reaction monitoring on a triple quadrupole mass spectrometer in the positive ionization mode. The linearity of the method was established in the concentration range of 0.5–200 ng/mL and 2.0–800 ng/mL for oseltamivir and oseltamivir carboxylate respectively. The mean extraction recovery for oseltamivir (94.4%) and oseltamivir carboxylate (92.7%) from spiked plasma samples was consistent and reproducible. The application of this method was demonstrated by a bioequivalence study in 42 healthy Indian subjects with 75 mg oseltamivir phosphate capsules. The assay reproducibility was established by reanalysis of 151 incurred subject samples.

No abstract