The authors developed four variants of the qNMR technique (1H or 13C nucleus, DMSO-d6 or CDCl3 solvent) for identification and quantification by NMR of 22R and 22S epimers in budesonide active pharmaceutical ingredient and budesonide drugs (sprays, capsules, tablets). The choice of the qNMR technique version depends on the drug excipients. The correlation of 1H and 13C spectra signals to molecules of different budesonide epimers was carried out on the basis of a comprehensive analysis of experimental spectral NMR data (1H-1H gCOSY, 1H-13C gHSQC, 1H-13C gHMBC, 1H-1H ROESY). This technique makes it possible to identify budesonide epimers and determine their weight ratio directly, without constructing a calibration curve and using any standards. The results of measuring the 22S epimer content by qNMR are comparable with the results of measurements using the reference HPLC method.

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.

Analysis of normative documents identified a tendency to eliminate differences in approaches to the normalization of heavy metals contents in medicinal substances, medicinal herbs, and herbal medicines. The current main principle of the normalization of heavy metals is the principle of selective assay.Medicinal herbs (MH) provide sources of more than a third of all drugs [1 -3]. The introduction of new types of MH and their processing products and enlargement of the arsenal of herbal medicines (Hmeds) generate the need for improvements in the quality control system. This applies primarily to increases in the stringency of requirements relating to the contents of various toxins. Heave metals are among the most dangerous toxic substances. Studies addressing the problems of environmental pollution and ecological monitoring have identified more than 40 metals and metalloids in the periodic table with atomic weights of more than 50 amu (V, Cr, Mn, Fe, Co, Ni, Cu, Zn, As, Mo, Cd, Sn, Hg, Pb, Bi, and others) [4 -6]. Some hold the view that the main cause of the toxic actions of heavy metals is linked with blockade of particular functional groups (especially protein sulfhydryl groups) or displacement of metal ions from various enzymes [7].The system for normalizing heavy metal content in MH and their processing products involves two parameters: the item being normalized and the acceptable content, which depend on the level of knowledge of toxic substances and the capabilities of the analytical apparatus. Improvements in the methods of elemental analysis and increases in the volume of experimental data obtained from studies of the anthropogenic actions on MH, the mechanisms of absorption and distribution of toxic elements in individual plant organs, correlational relationships between the selective accumulation of elements in plants and their contents of bioactive substances, and the kinetics of the extraction of toxic elements from MH into Hmeds have led to changes in our concepts of the level of risk of using medicinal herbs and agents based on them, with different heavy metal contents, in medical practice. This is reflected in the corresponding normative documentation regulating MH quality control. The aim of the present work was to perform an information analysis study of changes in the main measures used for normalization of heavy metals in MH and herbal medicines based on them in the normative documentation. EXPERIMENTAL SECTIONThe studies reported here were based on analysis and generalization of data from the scientific literature, the requirements of Russian and foreign pharmacopeias (American USP, Britain BP, Japanese JP, Chinese PC, European Eur.

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.The aim of the study was 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).

Gentamicin sulfate is a broad-spectrum bactericidal aminoglycoside antibiotic produced by Micromonospora purpurea and used in clinical practice as an active substance containing a mixture of gentamicins C1 and C2. Gentamicin content is a standardised parameter controlled as part of a pharmaceutical product review. Currently, the quality control of the active substance gentamicin sulfate involves the use of high-performance liquid chromatography (HPLC) for the indirect identification of the component composition by comparison with a reference standard and for its quantification by calibration against the reference standard.The aim of the study was to develop a procedure for identifying and quantifying the components of the active substance gentamicin sulfate using nuclear magnetic resonance (NMR) spectroscopy that would not require reference standards.Materials and methods. The authors studied a sample of the active substance gentamicin sulfate using an Agilent DD2 NMR spectrometer operating at 600 MHz to record NMR spectra and an Agilent 1200 HPLC system equipped with a multiple wavelength detector (MWD) to obtain chromatograms.Results. Having determined the spectral properties of the C1, C1A, C2, C2A and C2B gentamicins comprising the active substance, the authors observed characteristic signals of the same type that corresponded to each of the gentamicins and did not overlap with other signals in the 1H and 13C spectra. These characteristic signals provided spectral markers indicative of the gentamicins of interest in the sample, with normalised integrated intensities equal to the mole fractions of the analytes. The authors compared NMR and HPLC measurements of the active substance composition.Conclusions. The authors developed a procedure for identifying and quantifying the constituents of the active substance gentamicin sulfate by 1H and 13C NMR spectroscopy, which requires less effort than HPLC procedures and no reference standards for the intended applications.