Clinical development of imatinib: an anticancer drug.

Background: A novel and accurate high-throughput tandem mass spectroscopic method has been developed and validated for determination of imatinib, a inhibitor against chronic myeloid leukemia.

Materials & Methods: Chromatographic separation was carried on XTerra RP18 column (150 mm × 4.6 mm, 5 µm particle size) manufactured by Waters Corporation, MA, USA.

Development and Validation of an LC-MS-MS Method for Determination of Simvastatin and Simvastatin Acid in Human Plasma: Application to a Pharmacokinetic Study.

A liquid chromatography-tandem mass spectrometry method was developed and validated for the simultaneous determination of simvastatin (SV) and simvastatin acid (SVA) in human plasma. To improve assay sensitivity and achieve simultaneous analysis, SVA monitored in (-)ESI (electrospray ionization) mode within the first 4.5 min and SV thereafter in (+)ESI mode.

Liquid chromatography tandem mass spectrometry method for the quantitation of mycophenolate mofetil in human plasma: Application to a bioequivalence study and metabolite identification.

We established a sensitive, selective, and rapid analytical method for the quantitation and pharmacokinetic investigation of mycophenolate mofetil in human plasma. To our knowledge, this is the first method that characterizes presence of mycophenolate mofetil glucuronide in clinical samples through tandem mass spectrometry detection and resolves mycophenolate mofetil from its glucuronide metabolite. Liquid chromatography coupled to tandem mass spectrometry detection in positive ion mode was selected to provide optimal selectivity and sensitivity.

Liquid chromatography-tandem mass spectrometry method for the estimation of adefovir in human plasma: Application to a pharmacokinetic study.

An analytical method based on solid phase extraction was developed and validated for analysis of adefovir in human plasma. Adefovir-d was used as an internal standard and Synergi MAX RP80A (150 mm×4.6 mm, 4 µm) column provided the desired chromatographic separation of compounds followed by detection with mass spectrometry.

Development and Validation of a LC-MS/MS Method for the Simultaneous Estimation of Amlodipine and Valsartan in Human Plasma: Application to a Bioequivalence Study.

A reliable, simple, and robust liquid chromatography-tandem mass spectro-metric (LC-MS/MS) method has been developed and validated that employs solid-phase extraction for the simultaneous estimation of amlodipine and valsartan in human K3EDTA plasma using amlodipine-d4 and valsartan-d9 as internal standards. Chromatographic separation of amlodipine and valsartan was achieved on the Luna C18 (2)100A (150 × 4.6 mm, 5 μm) column using acetonitrile: 5 mM ammonium formate solution (80:20, v/v) as the mobile phase at a flow rate of 0.

Simultaneous quantitation of atorvastatin and its two active metabolites in human plasma by liquid chromatography/(-) electrospray tandem mass spectrometry.

A sensitive, accurate and selective liquid chromatography-tandem mass spectrometry method (LC-MS/MS) was developed and validated for the simultaneous quantitation of atorvastatin (AT) and its equipotent hydroxyl metabolites, 2-hydroxy atorvastatin (2-AT) and 4-hydroxy atorvastatin (4-AT), in human plasma. Electrospray ionization (ESI) interface in negative ion mode was selected to improve the selectivity and the sensitivity required for this application. Additionally, a solid phase extraction (SPE) step was performed to reduce any ion-suppression and/or enhancement effects.

Pharmacokinetic comparison and bioequivalence evaluation of losartan/ hydrochlorothiazide tablet between Asian Indian and Japanese volunteers.

Objectives: To demonstrate the bioequivalence between the test and reference formulations of losartan/hydrochlorothiazide 50 + 12.5 mg tablet and evaluate the effect of ethnicity on pharmacokinetics properties of losartan, losartan carboxylic acid and hydrochlorothiazide on healthy Asian Indian and Japanese volunteers.

Methods: Randomized, open-label, crossover, bioavailability studies were conducted separately in healthy Asian Indian and Japanese volunteers.

Development and validation of liquid chromatography-tandem mass spectrometric method for quantification of meropenem in rat plasma and its application in a preclinical dose proportionality study.

A simple, rapid, sensitive and selective assay based liquid chromatography-tandem mass spectrometric method was developed and validated for quantitative analysis of meropenem in rat plasma using rolipram as internal standard. Efficient chromatographic separation of analyte from matrix components was achieved by using Kromasil 100 C18 (150×4.6 mm, 5 µm) reversed phase column with mobile phase consisting of acetonitrile and 2 mM ammonium acetate buffer (80:20, v/v) delivered in isocratic mode with constant flow rate of 0.

Combining benefits of an adrenergic and a muscarinic blocker in a single formulation - a pharmacokinetic evaluation.

A pharmacokinetic bioequivalence study was conducted in Asian subjects, to compare a fixed dose combination capsule single oral dose of alpha adrenoceptor blocker-Alfuzosin hydrochloride 10mg extended release and muscarinic antagonists-Solifenacin succinate 5mg against individually administered Xatral XL 10mg tablets (Alfuzosin) of Sanofi Synthelabo Limited, United Kingdom (UK) and Vesicare 5mg tablets (Solifenacin) of Astellas Pharma Limited, UK under fed conditions. Blood samples were collected pre-dose up to 72 h post dose for determination of plasma Alfuzosin and Solifenacin concentrations and calculation of the pharmacokinetic parameters. ANOVA was performed on the log (natural)-transformed pharmacokinetic parameters.

Bioequivalence of oxycodone hydrochoride extended release tablets to marketed reference products OxyContin® in Canada and US.

Introduction: Oxycodone is a semisynthetic opioid agonist used for the relief of moderate to severe pain. A new generic oxycodone hydrochloride (HCl) extended release (ER) tablet is currently being developed by Ranbaxy Pharmaceutical Inc., New Brunswick, NJ, USA.

Development and validation of high performance liquid chromatographic method for analysis of clozapine.

In this study a rapid, simple and sensitive assay to quantify clozapine in human plasma by using reverse phase high performance liquid chromatographic method has been developed. Clozapine was extracted from human plasma using a mixture of chloroform: n-hexane 50:50 employing liquid-liquid extraction method. The calibration curve was found to be linear in the concentration range of 25-800 ng/ml.

Liquid chromatography tandem mass spectrometry method for the estimation of lamotrigine in human plasma: Application to a pharmacokinetic study.

A reliable, selective and sensitive liquid chromatography tandem mass spectrometry method was developed and validated for the quantification of lamotrigine in human plasma using lamotrigine-C3, d3 as an internal standard. Analyte and internal standard were extracted from human plasma by solid-phase extraction and detected in positive ion mode by tandem mass spectrometry with electrospray ionization (ESI) interface. Chromatographic separation was performed on a Chromolith SpeedROD; RP-18e column (50-4.

Liquid chromatography tandem mass spectrometry method for the simultaneous stereoselective determination of venlafaxine and its major metabolite, O-desmethylvenlafaxine, in human plasma.

A sensitive, accurate and highly stereoselective assay for the simultaneous determination of venlafaxine (VEN) and its equipotent metabolite, O-desmethyl venlafaxine (ODV), in human plasma was developed and validated. Analytes were simultaneously extracted from plasma using solid-phase extraction and detected by tandem mass spectrometry in positive ion mode with a turbo ion spray interface. Deuterium-labeled VEN and ODV were used as internal standards.

Metaxalone estimation in biological matrix using high-throughput LC-MS/MS bioanalytical method.

Metaxalone is a skeletal muscle relaxant, an approved drug for pain relief. Published bioanalytical methods lacked detailed stability evaluation in blood and plasma. An accurate, precise, high-throughput tandem mass spectroscopic method has been developed and validated.

Bioequivalence and pharmacokinetic comparison of 3 metformin extended/sustained release tablets in healthy Indian male volunteers.

This study was undertaken to compare the bioavailability and pharmacokinetic properties of 3 marketed product of metformin (CAS 1115-70-4) extended/sustained release formulation in Indian male volunteers. Study was designed as an open-label, randomized, 3-treatment, single-dose, crossover, bioavailability study comparing 3 marketed brands of 500 mg metformin extended/sustained release tablets in 18 healthy human male volunteers under fed condition. A single oral dose of 500 mg metformin sustained release products, test A (Glycomet SR), test B (Bigomet SR) and extended release reference product was administered as per computer generated randomization schedule during 3 period of the study having 7 days of washout period.

ESI-MS/MS stability-indicating bioanalytical method development and validation for simultaneous estimation of donepezil, 5-desmethyl donepezil and 6-desmethyl donepezil in human plasma.

A bioanalytical method was developed and validated to estimate donepezil, 6-desmethyl donepezil and 5-desmethyl donepezil simultaneously in human plasma using galantamine as an internal standard (IS). The chromatographic separation was achieved on a reverse-phase XTerra RP (150 × 4.6 mm, 5 µm) column without affecting recovery (mean recovery > 60% with CV < 10%) for all analytes.

Establishing bioequivalence of racemic venlafaxine formulations using stereoselective assay method: Is it necessary?

A bioequivalence study for venlafaxine generic formulation was conducted as an open label, balanced, randomized, two-way crossover, single-dose study. In this study, a comparison of various pharmacokinetic parameters of venlafaxine hydrochloride 150 mg modified release capsules of Ranbaxy and EFEXOR®-XR 150 mg capsules of Wyeth, in healthy, adult, male, human subjects under fasting condition was performed to conclude bioequivalence. Venlafaxine and its major active metabolite O-desmethylvenlafaxine (ODV) are racemates.

Pharmacokinetics of a fixed-dose combination of atorvastatin and metformin extended release versus concurrent administration of individual formulations: a randomized, open-label, two-treatment, two-period, two-sequence, single-dose, crossover, bioequivalence study.

Background: Type 2 diabetes mellitus is associated with a 2- to 4-fold increased risk of coronary heart disease (CHD). Combined therapy with an antihyperglycaemic agent and an HMG-CoA reductase inhibitor (statin) is indicated for the treatment of diabetic patients at risk of CHD. Patients with type 2 diabetes are generally considered to be at equivalent cardiovascular disease risk to patients with established CHD, and should have low-density lipoprotein (LDL) cholesterol levels reduced to <100 mg/dL or by 30-40%.

Pharmacokinetic-pharmacodynamic equivalence of three gliclazide formulations in healthy human male subjects.

Aims: To find out the pharmacokinetic (PK) and pharmacodynamic (PD) parameters for assessing the bioequivalence of three marketed products. To study the relationship between the pharmacokinetics of gliclazide and pharmacodynamic effect in healthy male volunteers.

Methods: This was an open label, balanced, randomized, 3-treatment, 3-sequence, 3 period, single-dose, cross-over bioavailability study in which 18 healthy adults were randomized to receive gliclazide 80 mg with 7 days wash out between treatments.

Determination of valganciclovir and ganciclovir in human plasma by liquid chromatography tandem mass spectrometric detection.

Objectives: The aim of this work was to develop a simple, sensitive and selective LC/MS/MS method for the assay of valganciclovir and ganciclovir in human plasma.

Design And Methods: Sample preparation involved solid phase extraction on mix mode cation exchanger. Separation was performed on Chromolith RP18e column using water, trifluoroacetic acid (1M, pH 4.

Controlled ex-vivo plasma hydrolysis of valaciclovir to acyclovir demonstration using tandem mass spectrometry.

Plasma estimation of valaciclovir, an antiviral drug, is challenging due to both in-vivo and ex-vivo hydrolysis to active metabolite acyclovir. A simultaneous method is described involving the solid-phase ion-exchange extraction procedure requiring 100 μL of plasma volume, a reverse-phase Lichrosphere RP Select B (125 × 6 mm, 5 μm) column and isocratic mobile phase to achieve the desired chromatographic separation. ESI-MS/MS multiple reaction monitoring in positive polarity, detected mass pairs for valaciclovir (m/z 325.

Bioequivalence of venlafaxine modified-release capsule revisited with an innovative approach using experimental and predictive models.

Background: To evaluate the venlafaxine:O-desmethyl venlafaxine (active metabolite) in vivo formation ratio (MR) in three independent bioequivalence (BE) studies consisting of single-dosed (under fasted and fed conditions) and multiple-dosed clinical trials on healthy subjects. The pooled data pharmacokinetic (PK) analysis demonstrates a model to conduct enantiomer/racemate/active metabolite bioanalysis for regulatory submission of bioavailability/bioequivalence (BA/BE) studies using an interesting MR concept.

Results: BE was established for all three studies.

A pharmacokinetic and bioequivalence study of Contiflo ICON 400 µg tablets in healthy Indian subjects.

Introduction: Tamsulosin, an alpha1 adrenoceptor blocking agent, exhibits selectivity for alpha1 receptors in human prostate. Blockade of these adrenoceptors can cause smooth muscles in the bladder neck and prostate to relax, resulting in an improvement in urine flow rate and a reduction in symptoms of benign prostatic hypertrophy. A new formulation Contiflo ICON 400 µg has been developed by Ranbaxy Laboratories Limited, India similar to Flomaxtra XL 400 µg of Astellas Pharma Limited, United Kingdom.

Rational design for variability minimization in bioanalytical method validation: illustration with LC-MS/MS assay method for terbinafine estimation in human plasma.

Terbinafine, a widely used antifungal drug, is a challenging molecule for quantitative bioanalysis due to certain factors contributing assay variability. Despite previous attempts at human plasma determination of terbinafine, exhaustive stability of the drug or an internal standard was lacking. Internal standard stability with negligible variation throughout the analysis is an indicator of a reliable bioanalytical method as the majority of LC-MS/MS assays are based on analyte/IS response ratios for quantitation.