NMR as Used in the Russian and Foreign Pharmacopoeias for Quality Control of Medicinal Products

The ongoing development of the Pharmacopoeia of the Eurasian Economic Union and the current trend for harmonisation of the Russian Pharmacopoeia with the world leading pharmacopoeias suggest the necessity of studying how different pharmacopoeias use nuclear magnetic resonance (NMR) for quality control of medicinal products. The aim of the study was to compare the extent of medicine quality characteristics assessed by NMR in the Russian and foreign pharmacopoeias. The review summarises the experience of various national and world pharmacopoeias in using the NMR method for quality control of medicines and certification of pharmacopoeial reference materials. The comparative analysis covered the following quality parameters: active ingredient identification, determination of the composition of non-stoichiometric compounds, determination of the average polymer chain length in polymers and block copolymers, determination of the absolute content of the active ingredient, identification and quantification of impurities, polymorphism, and crystallinity. It was shown that the United States and Japanese Pharmacopoeias are leading the way in introducing the NMR method into pharmacopoeial analysis. There have been some positive trends in the introduction of the NMR method in the State Pharmacopoeia of the Russian Federation as well. It was concluded that changes are needed in the general chapters “Nuclear Magnetic Resonance Spectroscopy” and “Reference Standards” of the State Pharmacopoeia of the Russian Federation, 14th ed. in order to harmonise the texts with those of the Eurasian Pharmacopoeia and the European Pharmacopoeia and to allow for the possibility of direct identification of a substance by complex analysis of NMR spectral data, without comparing the test sample and the reference standard spectra. The NMR method should be included in the list of absolute methods used for determination of purity of primary chemical reference substances during certification

Medication errors associated with carbapenems

Purpose. The purpose of this study was to discover the prevalence and types of medication errors associated with the use of carbapenems. Materials and methods. We analyzed 161 spontaneous reports concerning adverse drug reactions associated with the carbapenems. All the reports were submitted to the Russian pharmacovigilance database between 01.01.2012 and 01.08.2014. Approved prescribing drug information, standards of medical care and practical guidelines for certain conditions were used to identify medication errors associated with specific products. Results. The prevalence of medication errors associated with the use of carbapenems was 24,8%. The reporters indicated medication error-related term only in 5,0% of these cases. The most common types of identified medication errors (44,0%) were deviations from the recommended dosing scheme, in most cases (20,0%) medication errors resulted from wrong frequency of administration of the antibiotic. Conclusions. The results of this study show that the reporters rarely recognize and identify medication errors. We suggest emphasizing the importance of compliance with the dosage regimen of antibiotics; the frequency of administration of carbapenems is critical

Diffusion-Ordered NMR Spectroscopy Application for Analysis of Polysaccharides

Diffusion-ordered nuclear magnetic resonance spectroscopy (DOSY) is a molecular transport method in analytical chemistry, based on experimental recording of the molecules’ translational mobility at thermodinamic equilibrium in a solution. The translational mobility is characterised quantitatively by a self-diffusion coefficient. The aim of the study was to summarise the main trends in application of DOSY for the analysis of natural and modified natural polysaccharides used in pharmaceuticals and pharmaceutical biotechnology. The review shows that this method is an effective instrument for monitoring fractionation during isolation of polysaccharides from a natural mixture, for estimating their average molecular weight and molecular weight distribution, and for studying the formation of supramolecular systems based on polysaccharides. The paper describes main issues of the precise measurement of polysaccharide macromolecules self-diffusion coefficients and provides the correction factors to compensate for errors caused by fluctuations in temperature and viscosity of solutions. The observed scatter of self-diffusion coefficients of narrowly dispersed polymer macromolecules nuclei is explained using the polyphase concept. The paper illustrates ways of describing translational mobility of a polyphase polymer macromolecule as a whole. The authors summarise values of the gradient pulse sequence parameters used in quantitative measurements of self-diffusion coefficients of linear, low-branched, and branched polysaccharides

Determination of Heavy Metals, Arsenic, and Aluminum Content in Pumpkin Seed Herbal Substance and Native Products, by Inductively Coupled Plasma Mass Spectrometry

Pumpkin seeds belong to the so-called native products. Their characteristic feature is that they can be consumed directly, without prior extraction of the starting material. All elemental toxicants contained in pumpkin seeds are transferred in full to the native product. Therefore, it is important to study specific aspects of elemental toxicant accumulation by pumpkin seeds.The aim of the study was to determine the content of heavy metals, As, and Al in pumpkin seed herbal substance and native products, and to assess the degree of accumulation of these elements, depending on the vegetation area.Materials and methods: the study evaluated pumpkin seed native products by Russian manufacturers as well as pumpkin seeds harvested in areas with different anthropogenic load. The sample preparation was performed by microwave digestion, and the determination of the elemental toxicants was perfomed by inductively coupled plasma mass spectrometry.Results: the pumpkin seeds were shown to contain essential, probably essential, potentially toxic, and toxic elements. The authors performed comparative analysis of the elemental composition of pumpkin seeds as well as seeds, grains, and beans of various oil-bearing, grain, and leguminous crops.Conclusions: the content of the specified elemental toxicants (As, Cd, Hg, Pb) in the tested samples of pumpkin seed herbal substance and herbal medicinal products did not exceed the limits established by the Russian Pharmacopoeia. The unspecified toxic elements were either absent in pumpkin seeds (Tl) or found in trace amounts (Al). The content of a number of essential elements (Zn, Fe, Mn, Cu, Mo, Cr) in pumpkin seeds was higher than in the seeds of many oil-bearing crops. The vegetation area had no significant influence on the content of the tested elements in the pumpkin seeds. Pumpkin seeds are capable of accumulating abnormally high amounts of Cd, Co, and Ni in areas with high environmental pollution

Determination of zinc content in insulin products by inductively coupled plasma mass spectrometry

Scientific relevance. Zinc content is a quality attribute of insulin products. The State Pharmacopoeia of the Russian Federation requires that it should be determined by flame atomic absorption spectrometry (FAAS). However, many pharmaceutical manufacturers currently prefer inductively coupled plasma mass spectrometry (ICP-MS), which is considered the most promising method for pharmaceutical and biomedical elemental analysis.Aim. The study aimed to develop and validate an ICP-MS-based analytical procedure for zinc content determination in insulin products.Materials and methods. The study focused on human insulin, insulin lispro, insulin aspart, and insulin glargine in the form of active substances, suspensions for subcutaneous injection, and solutions for injection from different manufacturers. Zinc content was determined on an Agilent 7900 ICP-MS; the analysis included 66Zn signal intensity registration.Results. The study compared the results of zinc content determination in test samples with either hydrochloric or nitric acid used as the solvent for sample preparation. The authors selected the experimental conditions to achieve relative standard deviations (RSDs) of not more than 2.5% for the measurements. The ICP-MSbased analytical procedure was validated for its specificity, linearity, accuracy, and precision in the range of 0.4–1.6 mg/L. The authors compared the measurements of zinc content made using FAAS and ICP-MS.Conclusions. The ICP-MS-based analytical procedure for zinc content determination in insulin products meets the validation criteria. This analytical procedure, as developed and validated, may be used in the quality control of medicinal products in the Russian healthcare system and at the batch release stage of pharmaceutical manufacturing

Selective Quantification of Organic and Inorganic Arsenic in Kelp Thalli and Kelp-Based Products

Kelp can accumulate large quantities of arsenic compounds even in the absence of considerable environmental pollution. A substantial difference in toxicity between organic and inorganic arsenic compounds makes the form of arsenic relevant for the risk assessment of consuming kelp thalli and kelp-based products.The aim of the study was to develop an analytical procedure for the selective quantification of organic and inorganic arsenic in kelp thalli by inductively coupled plasma mass spectrometry and solid-phase extraction without scheduled precursors.Materials and methods. The authors studied samples of Laminaria saccharina and Laminaria japonica, spiking mixtures of chemical compounds containing arsenic in different oxidation states, and bioactive dietary supplements based on kelp thalli. Solid-phase extraction was performed using Maxi-Clean SAX cartridges. The arsenic content was determined using an Agilent 7900 inductively coupled plasma mass spectrometer.Results. Microwave-assisted extraction with deionised water ensures 91% recovery of arsenic-containing compounds from kelp thalli, and the addition of hydrogen peroxide to the extractant provides complete extraction. Solid-phase extraction with an eluent based on 3% H2O2 can extract the organic fraction from a mixture of organic and inorganic arsenic compounds without washing the inorganic fraction off the cartridge.Conclusions. The authors offer an effective analytical procedure for the selective quantification of organic and inorganic arsenic in kelp thalli and kelp-based products. This procedure allows for the isolation of arsenic-containing compounds from the organic matrix of kelp with 3% hydrogen peroxide. Solid-phase extraction with this extractant can effectively separate organic and inorganic fractions without prior neutralisation of the test solution

NMR Spectroscopy Study of the Effect of the Molecular Mass of Hypromellose Phthalate on Its Solubility

Scientific relevance. Hypromellose phthalate is used in enteric coatings for oral medicinal products. The proportion of phthalate groups in the polymer is standardised because it has a significant effect on solubility. Whereas, the molecular mass of hypromellose phthalate is not controlled, and its impact on solubility in media with different pH values is understudied.Aim. The study aimed to employ NMR spectroscopy to investigate the effect the molecular mass of hypromellose phthalate may have on the dissolution kinetics at the pH value declared by the polymer manufacturer.Materials and methods. The study analysed hypromellose phthalate isolated from proton-pump inhibitor enteric coatings and the hypromellose phthalate reference standard. The molecular mass of the polymer was estimated by diffusion-ordered NMR spectroscopy (DOSY) with polyethylene glycols of known molecular masses for calibration. The authors studied the dissolution profiles of hypromellose phthalates of different molecular masses using 1H NMR spectra.Results. The authors developed a procedure for estimating the average molecular mass of hypromellose phthalate by DOSY. The procedure showed variations in the molecular mass of the polymer in the test samples; the molecular mass scatter amounted to 10 kDa. The dissolution profile of the test samples in an aqueous buffer solution (pH 5.59) was described by a linear function during the first hour. The slope characterising the dissolution rate varied from 10° to 36°.Conclusions. The variation in the molecular mass of hypromellose phthalate significantly affects the dissolution rate of the test samples. The function of the dissolution rate against the molecular mass of hypromellose phthalate is non-linear. The article provides a compelling reason for further research to derive a correlation equation for the dissolution rate of hypromellose phthalate as a function of two variables (molecular mass and proportion of phthalate groups in the polymer)

NMR spectroscopy study of the structure of hypromellose phthalate, a component of enteric coatings of medicinal products

Scientific relevance. Hypromellose phthalate is a component of enteric coatings used to modify active substance release from oral medicinal products in the small intestine. The release rate directly depends on the non-stoichiometric composition of the polymer, first of all, on the proportion of phthalate groups in the macromolecule. It is therefore necessary to develop reliable analytical procedures for determining the structure of hypromellose phthalate to evaluate the dissolution rate of medicinal products containing the polymer.Aim. The study aimed to develop an analytical procedure for quantifying the proportion of phthalate groups in hypromellose phthalate samples using NMR spectroscopy and to determine the relationship between the polymer dissolution rate in aqueous buffer solutions and its structural features (degree of molar substitution and molecular mass).Materials and methods. The study examined hypromellose phthalate samples isolated from enteric coatings of proton-pump inhibitors and used the reference standard for hypromellose phthalate. The non-stoichiometric composition of the polymer was determined by 13C NMR spectroscopy.Results. The authors established the conditions required to separate hypromellose phthalate from the other coating components and identified the characteristic 13C NMR signals that may be used to differentiate between the structural fragments of hypromellose phthalate. The study demonstrated the relationship between the dissolution rate and the structure of the polymer. Commercial grades of hypromellose phthalate were shown to differ in composition and, as a result, in their dissolution kinetics (in particular, the threshold pH for the onset of dissolution (5.0–5.5), as well as the dissolution rates at the same pH).Conclusions. The authors developed NMR-based procedures to determine the proportion of phthalate groups on the basis of their mass fraction in a weighted hypromellose phthalate sample and the degree of molar substitution of the polymer. The results support the applicability of these analytical procedures to the characterisation of sample composition in polymer dissolution rate studies. In principle, it is possible to derive a multiple linear regression equation that describes the dissolution rate of hypromellose phthalate as a function of the molecular mass and the molar substitution with phthalate groups. Further investigation of a larger number of polymer samples with different compositions is needed to improve the regression model and demonstrate its statistical significance. In addition to the proportion of phthalate groups, the pharmacopoeial analysis of hypromellose phthalate should also control the molecular mass of the polymer

Разработка методик подтверждения подлинности фармацевтических субстанций трипторелина ацетат и гозерелина ацетат методом ЯМР-спектроскопии

The work is a continuation of the research on the use of NMR spectroscopy in the quality control of natural peptide hormone-based active substances and their synthetic analogues. The aim of the paper was to develop identification test methods for triptorelin acetate and goserelin acetate substances using NMR spectroscopy that does not require reference standards ‒ with the aim of using the newly developed test methods in pharmacopoeial analysis. Materials and methods: the procedure was developed using two-dimensional NMR spectroscopy (1H-1H gCOSY, 1H-13C gHSQC, 1H-13C gHMBC). Results: thestudy made it possible to assign 1H and 13C NMR signals to a specific molecular fragment, and to determine the amino acid composition of each oligopeptide. Conclusions: the authors drew up a table showing structural assignment of NMR signals, which makes it possible to use the NMR method for identification testing of triptorelin acetate and goserelin acetate substances without the use of pharmacopoeial reference standards. The study helped to determine the optimal temperature conditions for recording 13C NMR spectra (27 °С and 50 °С for triptorelin acetate and goserelin acetate, respectively). It was demonstrated that 13C NMR spectroscopy could be used for identification testing in pharmacopoeial analysis.  Работа является продолжением исследования по внедрению метода ЯМР-спектроскопии в контроль качества фармацевтических субстанций природных пептидных гормонов и их синтетических аналогов. Цель работы: разработка методик подтверждения подлинности фармацевтических субстанций трипторелина ацетата и гозерелина ацетата методом ЯМР-спектроскопии без использования стандартных образцов для их дальнейшего использования в фармакопейном анализе. Материалы и методы: при разработке методики были использованы методы двумерной ЯМР-спектроскопии (1H-1H gCOSY, 1H-13C gHSQC, 1H-13C gHMBC). Результаты: в процессе исследования проведено соотнесение сигналов 1Н и 13С ЯМР-спектров конкретному структурному фрагменту молекулы, определен аминокислотный состав и установлена аминокислотная последовательность каждого олигопептида. Выводы: составлена таблица структурного соотнесения сигналов спектров ЯМР, позволяющая использовать метод ЯМР для подтверждения подлинности фармацевтических субстанций трипторелина ацетат и гозерелина ацетат без использования фармакопейных стандартных образцов. Подобраны оптимальные температурные условия для регистрации 13C ЯМР-спектров (27 и 50 °С для трипторелина ацетата и гозерелина ацетата соответственно). Показана целесообразность использования в фармакопейном анализе методики подтверждения подлинности, основанную на методе 13C ЯМР-спектроскопии

Проблема проявления динамических процессов при решении задачи подтверждения подлинности органических соединений методом ЯМР-спектроскопии

The number, shape and position of NMR spectral lines depend on dynamic processes, and this creates certain difficulties in identification of pharmaceutical substances by NMR spectroscopy. The aim of the paper was to study instances of manifestation of intramolecular dynamic processes that affect identification of organic compounds by NMR, and to illustrate the potential of the methods used for their reduction, as well as associated problems.Materials and methods: 1H and 13C spectra of the following pharmaceutical substances: «buserelin acetate», «valsartan», «goserelin acetate», «iopromide», «clopidogrel hydrogensulfate», «omeprazole», «proroxan», «risperidone», «triptorelin acetate», and «enalapril maleate» were used to demonstrate negative effects of dynamic processes. The spatial structures of conformers were established by 1H-1H ROESY experiments. The quantum-chemical calculation of geometric and thermodynamic characteristics of different conformers was carried out by the PM3 method, and electronic characteristics—by the AM1 method with the help of the HyperChem software.Results: the authors analysed intramolecular dynamic processes which are most commonly encountered in expert work: pyramidal inversion of nitrogen in a heterocyclic compound (risperidone, proroxan, clopidogrel), rotation of molecular fragments around the amide bond (valsartan, iopromide, enalapril), prototropic rearrangements (buserelin, goserelin, omeprazole, triptorelin). The change in exchange rates was explained from the perspective of the change in the system of intra- and intermolecular nonvalent interactions.Conclusions: the use of traditional methods for increasing the rate of dynamic processes (increasing the temperature and changing the solvent) does not always eliminate the negative effects of intramolecular transformations. Methods of smoothing the spectral manifestations of dynamic processes have limited application due to strong intramolecular nonvalent interactions which prevent the conversion of the dynamic process rate into fast exchange. Experts and manufacturers should take into account the manifestation of dynamic processes during identification of pharmaceutical substances by NMR spectroscopy.Зависимость числа, формы и положения линий в ЯМР-спектре от динамических процессов создает определенные трудности при подтверждении подлинности фармацевтической субстанции методом ЯМР-спектроскопии.Цель работы: рассмотреть примеры проявления внутримолекулярных динамических процессов, отрицательно влияющих на процедуру идентификации органического соединения методом ЯМР, и показать возможности и ограничения способов их снижения.Материалы и методы: для иллюстрации отрицательных эффектов динамических процессов использованы ЯМР-спектры 1Н и 13С лекарственных субстанций: бусерелина ацетат, валсартан, гозерелина ацетат, йопромид, клопидогрела гидросульфат, омепразол, пророксан, рисперидон, трипторелина ацетат, эналаприла малеат. Пространственное строение конформеров устанавливали на основе данных 1Н-1Н ROESY экспериментов. Квантово-химический расчет геометрических и термодинамических характеристик различных конформеров проведен методом РМ3, электронных – АМ1 с использованием программы HyperChem.Результаты: рассмотрены наиболее часто встречающиеся в экспертной практике внутримолекулярные динамические процессы: пирамидальная инверсия конфигурации атома азота в гетероциклическом соединении (рисперидон, пророксан, клопидогрел), вращение фрагментов молекул вокруг амидной связи (валсартан, йопромид, эналаприл), прототропные перегруппировки (бусерелин, гозерелин, омепразол, трипторелин). Изменение скорости обмена объяснено с позиции изменения системы внутри- и межмолекулярных невалентных взаимодействий.Выводы: показано, что использование традиционных приемов увеличения скорости динамических процессов (увеличение температуры и смена растворителя) не всегда позволяет устранить отрицательные эффекты внутримолекулярных превращений. Ограничения в применении способов нивелирования спектральных проявлений динамических процессов связаны с сильными внутримолекулярными невалентными взаимодействиями, которые препятствуют переводу скорости динамического процесса в область быстрого обмена. Проявление динамических процессов необходимо учитывать экспертам и производителям при подтверждении подлинности фармацевтических субстанций методом ЯМР-спектроскопии