David Q. Liu

A generic approach for the determination of trace hydrazine in drug substances using in situ derivatization-headspace GC-MS.

In situ derivatization-headspace GC-MS methodology has been developed for the determination of hydrazine in drug substance at low ppm levels. This general method uses acetone or acetone-d(6) as the derivatization reagent. The resulting acetone azine or acetone azine-d(12) can then be analyzed by headspace GC-MS. The method gives excellent sensitivity with a limit of quantitation (LOQ) as low as 0.1ppm when the API (active pharmaceutical ingredient) samples are prepared at 10mg per headspace injection vial. The spike recoveries of hydrazine at the 1ppm level were between 79% and 117% in various APIs tested. The precisions (%RSD) of six preparations of the hydrazine standards at the concentration of 1ppm level were typically between 2.7 and 5.6%. A linear range of concentrations from 0.1 to 10ppm has been demonstrated with R(2)> or =0.999. This general method has been tested in a number of API matrices and successfully applied to the determination of hydrazine in support of API batch releases and process chemistry at GlaxoSmithKline.

A practical derivatization LC/MS approach for determination of trace level alkyl sulfonates and dialkyl sulfates genotoxic impurities in drug substances

Derivatization LC/MS methodology has been developed for the determination of a group of commonly encountered alkyl esters of sulfonates or sulfates in drug substances at low ppm levels. This general method uses trimethylamine as the derivatizing reagent for ethyl/propyl/isopropyl esters and triethylamine for methyl esters. The resulting quaternary ammonium derivatization products are highly polar (ionic) and can be retained by a hydrophilic interaction liquid chromatography (HILIC) column and readily separated from the main interfering active pharmaceutical ingredient (API) peak that is usually present at very high concentration. The method gives excellent sensitivity for all the alkyl esters at typical target analyte level of 1-2 ppm when the API samples were prepared at 5mg/mL. The recoveries at 1-2 ppm were generally above 85% for all the alkyl esters in the various APIs tested. The injection precisions of the lowest concentration standards were excellent with R.S.D.=0.4-4%. A linear range for concentrations from 0.2 to 20 ppm has been established with R(2)>or=0.99. This general method has been tested in a number of API matrices and used successfully for determination of alkyl sulfonates or dialkyl sulfates in support of API batch releases at GlaxoSmithKline.

Disposition of the dipeptidyl peptidase 4 inhibitor sitagliptin in rats and dogs.

The pharmacokinetics, metabolism, and excretion of sitagliptin [MK-0431; (2R)-4-oxo-4-[3-(trifluoromethyl)-5,6-dihydro[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl]-1-(2,4,5-trifluorophenyl)butan-2-amine], a potent dipeptidyl peptidase 4 inhibitor, were evaluated in male Sprague-Dawley rats and beagle dogs. The plasma clearance and volume of distribution of sitagliptin were higher in rats (40–48 ml/min/kg, 7–9 l/kg) than in dogs (∼9 ml/min/kg, ∼3 l/kg), and its half-life was shorter in rats, ∼2 h compared with ∼4 h in dogs. Sitagliptin was absorbed rapidly after oral administration of a solution of the phosphate salt. The absolute oral bioavailability was high, and the pharmacokinetics were fairly dose-proportional. After administration of [14C]sitagliptin, parent drug was the major radioactive component in rat and dog plasma, urine, bile, and feces. Sitagliptin was eliminated primarily by renal excretion of parent drug; biliary excretion was an important pathway in rats, whereas metabolism was minimal in both species in vitro and in vivo. Approximately 10 to 16% of the radiolabeled dose was recovered in the rat and dog excreta as phase I and II metabolites, which were formed by N-sulfation, N-carbamoyl glucuronidation, hydroxylation of the triazolopiperazine ring, and oxidative desaturation of the piperazine ring followed by cyclization via the primary amine. The renal clearance of unbound drug in rats, 32 to 39 ml/min/kg, far exceeded the glomerular filtration rate, indicative of active renal elimination of parent drug.

Analytical control of genotoxic impurities in the pazopanib hydrochloride manufacturing process.

Pharmaceutical regulatory agencies are increasingly concerned with trace-level genotoxic impurities in drug substances, requiring manufacturers to deliver innovative approaches for their analysis and control. The need to control most genotoxic impurities in the low ppm level relative to the active pharmaceutical ingredient (API), combined with the often reactive and labile nature of genotoxic impurities, poses significant analytical challenges. Therefore, sophisticated analytical methodologies are often developed to test and control genotoxic impurities in drug substances. From a quality-by-design perspective, product quality (genotoxic impurity levels in this case) should be built into the manufacturing process. This necessitates a practical analysis and control strategy derived on the premise of in-depth process understanding. General guidance on how to develop strategies for the analysis and control of genotoxic impurities is currently lacking in the pharmaceutical industry. In this work, we demonstrate practical examples for the analytical control of five genotoxic impurities in the manufacturing process of pazopanib hydrochloride, an anticancer drug currently in Phase III clinical development, which may serve as a model for the other products in development. Through detailed process understanding, we implemented an analysis and control strategy that enables the control of the five genotoxic impurities upstream in the manufacturing process at the starting materials or intermediates rather than at the final API. This allows the control limits to be set at percent levels rather than ppm levels, thereby simplifying the analytical testing and the analytical toolkits to be used in quality control laboratories.

Enhancing the detection sensitivity of trace analysis of pharmaceutical genotoxic impurities by chemical derivatization and coordination ion spray-mass spectrometry.

Many pharmaceutical genotoxic impurities are neutral molecules. Trace level analysis of these neutral analytes is hampered by their poor ionization efficiency in mass spectrometry (MS). Two analytical approaches including chemical derivatization and coordination ion spray-MS were developed to enhance neutral analyte detection sensitivity. The chemical derivatization approach converts analytes into highly ionizable or permanently charged derivatives, which become readily detectable by MS. The coordination ion spray-MS method, on the other hand, improves ionization by forming neutral-ion adducts with metal ions such as Na(+), K(+), or NH(4)(+) which are introduced into the electrospray ionization source. Both approaches have been proven to be able to enhance the detection sensitivity of neutral pharmaceuticals dramatically. This article demonstrates the successful applications of the two approaches in the analysis of four pharmaceutical genotoxic impurities identified in a single drug development program, of which two are non-volatile alkyl chlorides and the other two are epoxides.

Flow-injection MS/MS for gas-phase chiral recognition and enantiomeric quantitation of a novel boron-containing antibiotic (GSK2251052A) by the mass spectrometric kinetic method.

The present work demonstrates, for the first time, the application of the mass spectrometric kinetic method for quantitative chiral purity determination by automatic flow-injection MS/MS. The particular compound analyzed is GSK2251052A, a novel boron-containing systemic antibiotic for the treatment of multidrug-resistant Gram-negative bacterial infections. Chiral recognition and quantitation of GSK2251052A was achieved based on the competitive dissociation kinetics of the Cu(II)-bound trimeric complex [Cu(II)(A)(ref*)2-H](+) (A = GSK2251052A or its R-enantiomer, ref* = L-tryptophan) that gives rise to Cu(II)-bound dimeric complexes. The sensitive nature of the methodology and the linear relationship between the logarithm of the fragment ion abundance ratio and the optical purity, characteristic of the kinetic method, allow chiral purity determination of pharmaceutical compounds during enantioselective synthesis. By using flow-injection MS/MS, enantiomeric quantitation of GSK2251052A by the kinetic method proved to be fast (2 min for analysis of each sample) and to have accuracy comparable to chiral LC-MS/MS and LC-UV methods as well as the method using chiral derivatization followed by LC-MS/MS analysis. This flow-injection MS/MS method represents an alternative approach to commonly used chromatographic techniques as a means of chiral purity determination and is particularly useful for rapid screening of chiral drugs during pharmaceutical development.

Gas-phase derivatization via the Meerwein reaction for selective and sensitive LC-MS analysis of epoxides in active pharmaceutical ingredients.

A gas-phase derivatization strategy is reported by using the gas-phase Meerwein reaction for rapid and direct LC-MS analysis of epoxides, which are potential genotoxic impurities (GTIs) in active pharmaceutical ingredients (APIs). This class-selective ion/molecule reaction occurs between epoxides and the ethylnitrilium ion (CH(3)-C≡NH↔CH(3)-C=NH) that is generated by atmospheric pressure ionizations (when acetonitrile is used as the mobile phase). Density functional theory (DFT) calculations at the B3LYP/6-311+G(d,p) level show that the gas-phase Meerwein reaction is thermodynamically favorable. Commonly used atmospheric pressure ionization techniques including ESI, APCI and APPI were evaluated for optimal formation of the Meerwein reaction products. APCI appears to be the method of choice since it offers better sensitivity and more robust detection under typical LC-MS instrumentation conditions. Quantitative analysis of epoxides can be achieved by either single ion monitoring (SIM) or multiple reaction monitoring (MRM) of the Meerwein reaction products. We demonstrate herein quantitative analysis of two potential GTIs of SB797313 and SB719133 in APIs. The validated methods afford excellent linearity (r(2)≥0.999), sensitivity (LOD≤1 ppm by w/w in 10 mg/mL APIs) and recovery (ranging from 92% to 102%), as well as accuracy (≤2.8% difference) and precision (≤2.2% RSD) based on injections of six prepared standards. This novel strategy is particularly useful when a target analyte is difficult to be directly analyzed by LC-MS (e.g. due to poor ionization) or unstable in the course of solution-phase derivatization.

Gas-phase meerwein reaction of epoxides with protonated acetonitrile generated by atmospheric pressure ionizations.

AbstractEthylnitrilium ion can be generated by protonation of acetonitrile (when used as the LC-MS mobile phase) under the conditions of atmospheric pressure ionizations, including electrospray ionization (ESI) and atmospheric pressure chemical ionization (APCI) as well as atmospheric pressure photoionization (APPI). Ethylnitrilium ion ( % MathType!MTEF!2!1!+-% feaagaart1ev2aaatCvAUfKttLearuqr1ngBPrgarmWu51MyVXgatC% vAUfeBSjuyZL2yd9gzLbvyNv2CaeHbd9wDYLwzYbItLDharyavP1wz% ZbItLDhis9wBH5garqqtubsr4rNCHbGeaGqiVu0Je9sqqrpepC0xbb% L8F4rqqrFfpeea0xe9Lq-Jc9vqaqpepm0xbba9pwe9Q8fs0-yqaqpe% pae9pg0FirpepeKkFr0xfr-xfr-xb9adbaqaaeGaciGaaiaabeqaam% aaeaqbaaGcbaaceaGaa83qaiaa-HeadaWgaaWcbaGaa83maaqabaGc% cqGHsislcaWFdbGaeyyyIO7aaCbiaeaacaWFobaaleqabaGaey4kaS% caaOGaa8hsaaaa!4395!

A novel GC–MS method for rapid determination of headspace oxygen in vials of pharmaceutical formulations

CH_3 - C \equiv \mathop N\limits^ + H