Natalia Evgenievna Kuz'Mina

Экспериментально установлено, что ряд препаратов с кишечнорастворимыми оболочками на основе сополимеров метакриловой кислоты и этилакрилата (1:1), которые должны быть устойчивы в кислой среде, растворяются при pH 4,5. Известно, что растворимость сополимеров существенно зависит от их молекулярной массы. Цель данного исследования — оценка влияния молекулярной массы сополимеров метакриловой кислоты и этилакрилата (1:1) на различную устойчивость к растворению при pH 4,5. В качестве объектов исследования использовали 14 образцов сополимеров, выделенных из кишечнорастворимых оболочек препаратов пантопразола, омепразола, диклофенака, эритромицина отечественных и зарубежных производителей, которые характеризуются различной устойчивостью к растворению в слабокислой среде. Сополимеры метакриловой кислоты и этилакрилата предварительно переводили в сополимеры натриевых солей метакриловой кислоты и этилакрилата, чтобы избежать образования конгломератов из макромолекул. Средневесовую молекулярную массу определяли методом диффузионно-упорядоченной спектроскопии ЯМР. Расчет коэффициентов самодиффузии макромолекул проводили, учитывая влияние вязкости испытуемых растворов на его величину и различную локальную подвижность сегментов сополимерной цепи. Установлено, что значения средневесовых молекулярных масс испытуемых образцов с учетом доверительных интервалов близки к 250 и 320 кДа, что соответствует номинальным значениям этого показателя у основных производителей сополимеров метакриловой кислоты и этилакрилата (1:1). Сделан вывод, что неустойчивость кишечнорастворимых оболочек препаратов при pH 4,5 не связана с отклонением средней молекулярной массы сополимера оболочки от номинального значения.

Introduction. Methacrylic acid copolymers are synthetic anionic copolymers that are used as the main component of enteric-soluble coatings that provide controlled drug release in the small intestine. The molecular weight of these copolymers is a critical parameter affecting their solubility in the gastrointestinal tract, therefore it is among the normalized parameters that determine the quality of copolymers. Aim. Development of a method for determining the weight average molecular weight of methacrylic acid copolymers by diffusion-ordered NMR spectroscopy, which does not involve the stage of converting the molecular weight of derivatives into the molecular weights of the initial methacrylic acid copolymers. Materials and methods. A solution of the sodium salt of polymethacrylic acid, copolymers of methacrylic acid from various manufacturers, as well as copolymers of methacrylic acid isolated from pharmaceutical film coatings were used as objects of research. The DOSY experiments were performed on an Agilent DD2 600 NMR spectrometer. Results and discussion. Using a set of comparison samples, a calibration graph of the dependence of the logarithm of the weight average molecular weight of the comparison samples on the logarithm of their adjusted average value of the self-diffusion coefficient was constructed and a correlation equation with a coefficient of determination R ² = 0.9992 was derived. The values of the molecular weights of the tested samples calculated using this correlation equation agreed within the confidence intervals with the values measured by the coating manufacturers using the GPC method. The relative measurement error of the DOSY method (5.6 %) does not exceed the relative error of the determination of molecular weights by the GPC method (5–10 %). Conclusion. In the course of the study, a method was developed for determining the weight average molecular weight of methacrylic acid copolymers by diffusion-ordered NMR spectroscopy. When implementing this technique, the possibility of formation of methacrylic acid copolymers conglomerates due to their derivatization into the corresponding sodium salts is excluded; recalculation of the weight average molecular weight of the derivatized methacrylic acid copolymers into the weight average molecular weight of the initial methacrylic acid copolymers is excluded; different mobility of individual macromolecule segments is taken into account; the effect of the viscosity of the analyzed solutions on the measured value of the self-diffusion coefficient has been reduced. The relative error in measuring the weight average molecular weight of methacrylic acid copolymers using the developed technique does not exceed the relative error in measuring the molecular weights of substances by the GPC method.

INTRODUCTION . Gadobutrol is a macrocyclic gadolinium-based contrast agent used in diagnostic magnetic resonance imaging (MRI). In accordance with pharmacopeial requirements, the determination of elemental impurities in this substance is mandatory. The high concentration of gadolinium in the matrix, relative to the regulated permissible limits of target impurities, necessitates specialized methodological approaches for elemental analysis. AIM . To develop and validate a method for determining elemental impurities in gadobutrol using inductively coupled plasma mass spectrometry. MATERIALS AND METHODS . The method was developed using model mixtures containing standard solutions of the elements analyzed (Cd, Pb, As, Hg, Co, V, Ni, Tl, Au, Pd, Ir, Os, Rh, Ru, Se, Ag, Pt, Li, Sb, Ba, Mo, Cu, Sn, and Cr). The oxidant mixtures and digestion methods were varied. Validation samples were prepared using a 200-fold dilution of gadobutrol (blank solution), to which varying amounts of standard solutions of the elements were added. The elemental content was determined using an Agilent 7900 inductively coupled plasma mass spectrometer. When selecting the measured Pt and Se isotopes, isobaric interferences arising from high concentrations of Gd in the matrix (198Pt and 82Se) were taken into account. To suppress polyatomic interference, a collision cell operated in helium mode was used. The following stabilizers were used to bind OsO4: aqueous solutions of sodium sulfite (7.5 g/L), potassium bisulfite (7.5 g/L), and thiourea (1 g/L). RESULTS . It was found that the use of H2O2 does not result in a significant improvement in element recovery. The optimal sample preparation is microwave digestion in a 4:1 mixture of nitric and hydrochloric acids at 150 °C. Thiourea solution is the most effective stabilizing agent for obtaining accurate Os determination results. The assessed validation parameters (linearity, accuracy, repeatability, within-laboratory precision, and specificity) meet pharmacopeial acceptance criteria. The working range of the method enables the determination of all regulated elements at the levels specified by pharmacopeial requirements. CONCLUSIONS . The developed and validated method is recommended for implementation in the assessment of risks associated with the potential adverse effects of elemental impurities introduced into the human body upon administration of the Gadobutrol medicinal product.

INTRODUCTION. According to pharmacopoeial requirements, during the development and validation of the manufacturing process for radiopharmaceuticals, it is necessary to determine the content of impurities such as Pb, As, and Fe, as well as other elements that contribute most to the contamination of the drug product (for [ ¹⁸ F]-PSMA-1007, these elements are Al, Zn, Cu, and Li). Previously, we developed a method for quantifying elemental impurities in [ ¹⁸ F]-fluorodeoxyglucose using inductively coupled plasma mass spectrometry. The current study aims to assess its applicability to [18F]-PSMA-1007. AIM. Validation of the method for determining the content of Al, As, Cu, Zn, Fe, Pb and Li in the radiopharmaceutical [18F]-PSMA-1007 by inductively coupled plasma mass spectrometry. MATERIALS AND METHODS. The tests were carried out on a sample of the radiopharmaceutical [ ¹⁸ F]-PSMA-1007 with minimal content of the target impurities, to which varying amounts of standard solutions of the determined elements were added. The content of elements was determined using an Agilent 7900 mass spectrometer; the signal intensities of isotopes (amu) 7Li, 27Al, 57Fe, 63Cu, 66Zn, 75As, and 208Pb were recorded. RESULTS. It was established that the method for determination of elemental impurities in the radiopharmaceutical [ ¹⁸ F]-PSMA-1007 meets the validation requirements specified in the State Pharmacopoeia of the Russian Federation, 15th edition. The correlation coefficient of the linear dependence of signal on concentration for all determined elements is ≥0.99; the ratio of relative standard deviations at the minimum and maximum calibration levels is in the range of 0.5–2.0. The recovery of the method is characterized by acceptable accuracy (80–120%) for all determined elements. The relative standard deviation for all elements is ≤20% (repeatability) and ≤25% (intermediate precision). The actual values of the Fisher and Student test criteria are significantly below the critical values. The specificity of the method was confirmed, which allows unambiguous determination of each element in the presence of other elemental impurities and components. CONCLUSIONS. The analytical method for determining elemental impurities by mass spectrometry in [ ¹⁸ F]-fluorodeoxyglucose is applicable to the radiopharmaceutical [ ¹⁸ F]-PSMA-1007. The method can be used by manufacturers of this radiopharmaceutical both for validation of their manufacturing process and, if necessary, for internal quality control of their products.

Introduction. As a result of the search for more active polyfluoro-containing structural analogs of the non-steroidal antiandrogen flutamide against prostate cancer, a number of compounds were obtained, among which 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9-heptadecafluoro- N -(4-nitro-3-(trifluoromethyl)phenyl)nonanamide (code F-4) was of the greatest interest for further study. The necessary data for rigorous proof of the molecular structure of this compound have not previously been obtained. Identification of impurities and quantitative assessment of their content in the F-4 substance have not been conducted. To address these issues, we used nuclear magnetic resonance (NMR) spectroscopy and high-performance liquid chromatography with ultraviolet (HPLC-UV) and tandem mass-selective detection (HPLC-MS/MS). Aim. Comprehensive analysis of the structure of compound F-4 using NMR and HPLC methods, as well as identification and quantitative assessment using them of the content of impurities in samples of the substance. Materials and methods. The object of the study were laboratory samples of the substance of compound F-4, obtained by acylation of 4-nitro-3-(trifluoromethyl)aniline with perfluoropelargonic acid chloride using a known method. The following were used for the analysis: NMR spectrometer Agilent DD2 NMR System 600; liquid chromatograph Agilent 1200 equipped with diode array detector G1315B; liquid chromatograph Agilent Infinity II equipped with mass spectrometric detector with triple quadrupole G6495C (Agilent Technologies, USA). Both chromatographs used a column Luna C18(2), 250 × 4.6 mm, 5 μm (Phenomenex, USA). Results and discussion. Structural interpretation of the ¹ H, ¹³ C, and ¹⁹ F NMR spectra of F-4 samples, taking into account the chemical shift values of the signals, their multiplicity, and 2D experimental data, clearly indicates that F-4 has the structure of 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9-heptadecafluoro- N -(4-nitro-3-(trifluoromethyl)phenyl)nonanamide. The ¹ H and ¹⁹ F NMR spectra of the F-4 substance samples also contained signals of two impurity compounds not related to the starting materials. HPLC-UV method was used to separate them. Using HPLC-MS/MS with electrospray ionization in the negative mode (–ESI), high-intensity m/z signals characteristic of deprotonated molecular ions were recorded for all peaks. The structure of the detected impurities was confirmed using NMR spectroscopy. The results of quantitative determination of the relative impurity content in samples of F-4 substance using ¹ H and ¹⁹ F NMR methods were virtually identical; the differences between the obtained average values were not statistically significant. Conclusion. A comprehensive study using NMR and HPLC methods revealed that compound F-4 corresponds to the structure of 2,2,3,3,4,4,5,5,6,6,7,7,8,8,9,9,9-heptadecafluoro- N -(4-nitro-3-(trifluoromethyl)phenyl)nonanamide. Two related impurities were identified in samples of substance F-4, the relative content of each impurity did not exceed 1.7 %.

Экспериментально установлено, что ряд лекарственных средств c оболочками на основе сополимеров метакриловой кислоты и этилакрилата, которые должны быть устойчивы в кислой среде, растворяются при рН 4,5. Для понимания причины этого явления методом ЯМР проведен сравнительный анализ нестехиометрического состава и микроструктуры сополимеров метакриловой кислоты и этилакрилата с различной растворимостью. Представлена структурная интерпретация спектров 1H и 13C ЯМР сополимера метакриловой кислоты и этилакрилата. Для 10 образцов сополимеров методом 1Н ЯМР оценены массовые доли метакриловой кислоты, а методом 13С ЯМР — микроструктура сополимеров. Установлено, что различный профиль растворения этих образцов не связан с особенностями их строения. Сделано предположение, что неустойчивость оболочки препаратов при рН 4,5 обусловлена нарушением технологического процесса ее нанесения или отклонением средней молекулярной массы сополимера оболочки от номинального значения.

Background . Capreomycin is a multicomponent natural antibiotic and is a mixture of 4 related compounds (capreomycins IA, IB, IIA, and IIB). Quality control of capreomycin medicinal preparations by active substance is carried out according to the «capreomycin I» indicator, not taking into account the individual contributions of capreomycins IA and IB. With this approach, no correlation is observed between the total content of capreomycin IA and IB components determined by chromatographic methods and capreomycin activity determined by microbiological methods. WHO recommended studying the feasibility of introducing the ratio between capreomycin IA and IB in the specifications for capreomycin preparations. The aim of the study was to develop a technique for quantitative estimation of the capreomycin IA and IB content ratio in the drug preparation Capreomycin sulphate using NMR spectroscopy. Objects of the study . Capreomycin sulphate standard samples, pharmaceutical preparations Capreomycin, powder for preparation of solutions for intravenous and intramuscular administration from various manufacturers. Material and methods: NMR spectroscopy, HPLC. Results. Structural interpretation of 1H and 13C spectra of capreomycin sulfate in D₂O solution was performed. 13C spectra revealed characteristic signals of capreomycin IA and IB, which did not overlap with the signals of minor capreomycin components and related impurities. On the basis of normalized integral intensities, the ratio of mole fractions of capreomycin IA and IB (IA/IB) was calculated. The results of IA/IB measurement using 13C NMR and HPLC practically coincide when the chromatographic conditions allow separating the signals of the major and impurity components of capreomycin on the chromatogram.

INTRODUCTION . When developing and validating manufacturing of a product, Russian radiopharmaceutical manufacturers are required to detect ubiquitous impurities (Pb, As, Fe as well as other elements) causing contamination. At the stage of preliminary monitoring, Al, Cu, and Zn were found to most often contribute to fluorodeoxyglucose ( ¹⁸ F) elemental contamination. AIM . This study aimed to develop and validate a technique detecting Al, As, Cu, Fe, Pb, and Zn in fluorodeoxyglucose ( ¹⁸ F) using inductively coupled plasma mass spectrometry (ICP-MS). MATERIALS AND METHODS . The technique was developed on a model mixture simulating fluorodeoxyglucose (18F). A sample with minimum analysed impurities was used for validation; then varying amounts of standard analyte solutions were added. The content was determined using Agilent 7900 mass spectrometer. Signal intensities of the following isotopes (a.u.m.) were recorded: ²⁷ Al, ⁵⁷ Fe, ⁶³ Cu, ⁶⁶ Zn, ⁷⁵ As, and ²⁰⁸ Pb. RESULTS . The organic matrix was found to insignificantly affect elemental analysis. Due to matrix effect, NaCl reduced spike recovery of Al, Cu, Pb, and Zn to the level below 70%. When diluting model mixture tenfold, spike recovery of the analytes reached 90–101%. Correlation coefficients of element concentration — signal intensity linear dependences for the analytes exceeded 0.99. When estimating precision, RSD values did not exceed 10%. CONCLUSIONS . A technique has been developed detecting Al, As, Cu, Fe, Pb, and Zn in fluorodeoxyglucose ( ¹⁸ F) using ICP-MS. This technique considers influence of matrix components on quantification of target elements when preparing samples. Validation parameters of the technique comply with pharmacopoeial requirements.

INTRODUCTION . Radiopharmaceutical manufacturers should assess potential negative impact of elemental impurities on the quality of their products using real data of their elemental contamination. Accumulating knowledge about medicinal products and their manufacturing process should start from the development stage and continue throughout the implementation stage until production finally ends. AIM . This study aimed to monitor elemental impurities content in Russian radiopharmaceuticals using inductively coupled plasma mass spectrometry. MATERIALS AND METHODS . The samples included 127 Russian radiopharmaceuticals obtained by the Scientific Center for Expert Evaluation of Medicinal Products during its statutory activities: fluorodeoxyglucose ( ¹⁸ F), PSMA-1007 ( ¹⁸ F), sodium iodide ( ¹³¹ I), sodium iodohippurate ( ¹³¹ I), iobenguane ( ¹²³ I), and sodium pertechnetate ( ^99m Tc). The content of Ag, Al, As, Au, Ba, Be, Bi, Cd, Co, Cr, Cu, Fe, Ga, Ge, Hg, Ir, Li, Mn, Nb, Ni, Os, Pb, Pd, Pt, Rh, Ru, Sb, Se, Mo, Sn, Tl, V, W, and Zn was detected on the Agilent 7900 mass spectrometer. RESULTS . Elemental impurities Ag, As, Au, Bi, Be, Cd, Co, Cr, Ga, Ge, Hg, Ir, Mo, Nb, Ni, Os, Pb, Pd, Pt, Rh, Ru, Sb, Se, Sn, Tl, V, and W were not detected in any of the tested radiopharmaceuticals. Al, Zn, and Cu mostly contributed to elemental contamination in almost all radiopharmaceuticals. Radiopharmaceuticals used for single-photon emission computed tomography (SPECT) contained significantly less elemental impurities compared to positron emission tomography (PET) radiopharmaceuticals. CONCLUSIONS . The elements that mostly contaminate Russian radiopharmaceuticals are non-toxic or low-toxic (Al, Zn, Cu). These impurities should be monitored in case they negatively impact the quality of radiopharmaceuticals. In fluorodeoxyglucose ( ¹⁸ F), elemental contamination heavily depends on the used buffer solution. In order to find out elemental contamination sources in the studied radiopharmaceuticals, an additional analysis of impurities in the raw materials, reagents and semi-products is indispensable at all technological stages.

INTRODUCTION . Current risk-based general strategies for the control of elemental impurities in medicinal products, as documented in the elemental impurity monographs of national and world pharmacopoeias, do not apply to radiopharmaceuticals. Manufacturers of radiopharmaceuticals have to determine and substantiate the lists of specified elemental impurities and their limits. AIM . This study aimed to develop a control strategy for elemental impurities in radiopharmaceuticals by analysing the requirements of national and world pharmacopoeias to the levels of specified elemental impurities in radiopharmaceuticals. DISCUSSION . Limits for the amounts of elemental impurities in specific radiopharmaceuticals are provided in individual monographs of pharmacopoeias (24 monographs in the European Pharmacopoeia, 7 monographs in the Indian Pharmacopoeia, 7 monographs in the State Pharmacopoeia of the Russian Federation, 6 monographs in the United States Pharmacopeia, 6 monographs in the Japanese Pharmacopoeia, 6 monographs in the Pharmacopoeia of the People’s Republic of China, and 4 monographs in the Korean Pharmacopoeia). Individual monographs for the same radiopharmaceuticals differ in the lists of elemental impurities and the corresponding limits. Moreover, these monographs lack common criteria for selecting elemental impurities and establishing limits for them. In most cases, limits are set for the parent non-radioactive elements, the elements that are added as components of radiolytic stabilisers or sorbents (Ti, Zr, Sn, and Al oxides), and the elements that decrease radiolabelling efficiency (Cu, Fe, Pb, and Zn in ¹⁷⁷ Lu solutions; Cu, Cd, and Fe in ¹¹¹ InCl solutions; Cd, Cu, Fe, Pb, and Zn in ⁹⁰ Y solutions; etc.). Elemental impurity limits for radiopharmaceuticals are calculated on the basis of the acceptable impact on the physicochemical, biological, and radiochemical properties of the product used and the dose administered. The elements that lack specified permitted daily exposure (PDE) limits are subject to specification if these elements affect the target organ or the process of medicinal product radiolabelling. There is also no unified approach to limiting the amounts of elemental impurities in radiopharmaceutical precursors. CONCLUSIONS . This article provides radiopharmaceutical manufacturers with a control strategy for elemental impurities in finished medicinal products, based on assessing the risk of elemental impurities having a negative impact on the quality attributes of medicinal products. This strategy includes generalised criteria for selecting the list of specified impurities and their limits for radiopharmaceuticals, which significantly streamlines the preparation of regulatory documentation concerning this quality attribute.