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Accurate, precise, and sensitive LC-MS/MS assay method for the determination of montelukast (MO) in human plasma samples using gliclazide (GL) as internal standard was developed and applied in pharmacokinetics study.MO extracted by protein precipitation using acetonitrile. Chromatographic separation was carried out using a Agilant Triple quadrupoles mass spectrometer with API source with an Agilant SB- C18 (50×4.6 mm), 1.8 µm particle size column. A mobile phase consisting of acetonitrile: 0.1% formic acid (84:16) was delivered. Calibration curves were linear in the concentration range of (10.00-800.00) ng/ml. The bioanalytical method for determination of MO was successfully applied to assess pharmacokinetics of montelukast. The LLOQ was sensitive enough for detecting terminal phase concentrations of the drug. This study showed that developed method is suitable for MO pharmacokinetic study., (© Georg Thieme Verlag KG Stuttgart · New York.)

Zafirlukast is a selective leukotriene receptor antagonist used for the prophylaxis and chronic treatment of asthma. The aim of the present study was to develop a simple sensitive ultra-performance liquid chromatography tandem mass spectroscopy method for rapid determination of zafirlukast in plasma. After a simple one step protein precipitation by acetonitrile, zafirlukast and montelukast (IS) were separated on Acquity UPLC BEH(TM) C18 column (50 × 2.1 mm, i.d. 1.7 µm, Waters, USA) using a mobile phase of acetonitrile:water containing 10 mM acetic acid (80:20, v/v) at a flow rate of 0.3 mL/min. Zafirlukast and IS were eluted at 0.51 and 1.1 min, respectively with a total run time of only 1.5 min. The mass spectrometric determination was carried out using an electrospray interface operated in the negative mode with multiple reactions monitoring mode. The precursor to product ion transitions of m/z 574.11>462.07 and m/z 584.2>472.1 were used to quantify zafirlukast and IS, respectively. The method was linear in the concentration range of 0.17-600 ng/mL with coefficients of determination greater than 0.996 and lower limit of quantitation of 0.17 ng/mL. Intra-day and inter-day accuracies were 88.3-113.9% and the precisions were ≤ 12.6%. Zafirlukast was found to stable under various storage and sample processing conditions as per guidelines of bio-analytical method validation. The method developed herein is simple and rapid, and was successfully applied for the pharmacokinetic study in rabbits., (© Georg Thieme Verlag KG Stuttgart · New York.)

In order to assess the bioequivalence of 2 different formulations of montelukast, a pivotal trial for the montelukast 10 mg film-coated tablets formulation and a pivotal trial for the montelukast 5 mg chewable tablets formulation were conducted.For the 10 mg study, 34 healthy subjects were enrolled in a single centre, randomised, single-dose, open-label, 2-way crossover study, with a minimum washout period of 7 days, while for the 5 mg study, 42 healthy subjects were included in another study with a similar design. For both studies, plasma samples were collected up to 24 h post-dosing and drug levels were determined by reverse liquid chromatography and detected by tandem mass spectrometry detection.Pharmacokinetic parameters used for bioequivalence assessment, area under the concentration-time curve from time zero to time of last non-zero concentration (AUC0-t) and from time zero to infinity (AUC0-inf) and maximum observed concentration (Cmax), were determined from the drug concentration data using non-compartmental analysis.In the 10 mg study, the 90% confidence intervals obtained by analysis of variance were 99.62-120.51% for Cmax, 102.25-117.37% for AUC0-t and 101.96-116.67% for AUC0-inf, which were within the predefined acceptable range of 80.00-125.00%.In the 5 mg study, the 90% confidence intervals were 91.14-98.46% for Cmax, 93.02-98.42% for AUC0-t and 93.09-98.63% for AUC0-inf, which were within the predefined acceptable range of 80.00-125.00%.Bioequivalence between formulations was concluded both in terms of rate and extent of absorption for both strengths., (© Georg Thieme Verlag KG Stuttgart · New York.)