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Introduction. Coronavirus disease 2019 (COVID-19) is an infectious disease caused by the SARS-CoV-2 virus (severe acute respiratory syndrome-related coronavirus 2). COVID-19 is now expected to stay with us for many years as a recurring disease. Molnupiravir and favipiravir are oral antiviral drugs with anti-RNA polymerase activity. The Russian Health Ministry has approved molnupiravir and favipiravir for the treatment of COVID-19. The study describes development and validation of high-performance liquid chromatography – tandem mass spectrometry (HPLC-MS/MS) method for the simultaneous determination of β-D-N4-Hydroxycytidine and favipiravir in human blood plasma. The method could be applied in pharmacokinetic study of molnupiravir and favipiravir.Aim. The aim of this study is to develop and validate a HPLC-MS/MS bioanalytical method for the determination of β-D-N4-Hydroxycytidine and favipiravir in human plasma.Materials and methods. The determination of β-D-N4-Hydroxycytidine and favipiravir in human plasma by HPLC-MS/MS. The samples were processed by 0.1 % formic acid in acetonitrile. Internal standard: promethazine. Mobile phase: 0.01 mol/L Ammonium formate buffer solution (Eluent A), 0.1 % formic acid and 0.08 % aqueous ammonia in water/acetonitrile 10 : 90 (Eluent B). Column: Shim-pack GWS C18, 150 × 4.6 mm, 5 μm. Analytical range: 50.00–10000.00 ng/mL for β-D-N4-Hydroxycytidine, 250.00–20000.00 ng/mL for favipiravir in human plasma. Ionization source: electrospray ionization. Detection conditions: 260.00 m/z → 82.10 m/z, 260.00 m/z → 111.00 m/z, 260.00 m/z → 127.95 m/z (β-D-N4-Hydroxycytidine); 156.15 m/z → 65.95 m/z, 156.15 m/z → 85.00 m/z, 156.15 m/z → 113.10 m/z (favipiravir); 285.05 m/z → 198.05 m/z (promethazine).Results and discussion. This method was validated by selectivity, suitability of reference standard, matrix effect, calibration curve, accuracy, precision, spike recovery, the lower limit of quantification, carry-over effect and stability.Conclusion. The HPLC-MS/MS method for quantitative determination of β-D-N4-Hydroxycytidine and favipiravir in human plasma was developed and validated. The analytical range was 50.00–10000.00 ng/mL for β-D-N4-Hydroxycytidine, 250.00–20000.00 ng/mL for favipiravir in human plasma. This method was applied to investigate the pharmacokinetics of molnupiravir and favipiravir.

Introduction. Coronavirus disease (COVID-19) is an acute infectious disease caused by SARS-CoV-2 (severe acute respiratory syndrome-related coronavirus 2). Favipiravir is a synthetic prodrug with antiviral activity used for the treatment of COVID-19. There are oral and parenteral dosage forms of favipiravir. Compared with oral administration, parenteral administration has some advantages. Developing a method for the determination of favipiravir in human blood plasma is necessary for performing the analytical part of clinical studies of favipiravir for parenteral administration as an infusion, studying pharmacokinetics, and choosing the optimal dosage of the drug.Aim. The aim of this study is to develop and validate a method for quantitative determination of favipiravir in human plasma by high-performance liquid chromatography with ultraviolet detection (HPLC-UV) for pharmacokinetic studies.Materials and methods. Determination of favipiravir in human plasma by HPLC-UV. The UV detection was set at 323 ± 2 nm. The samples were processed by methanol protein precipitation. Internal standard: raltegravir. Mobile phase: 0.1 % formic acid in water with 0.08 % aqueous ammonia (eluent A), 0.1 % formic acid in acetonitrile with 0.08 % aqueous ammonia (eluent B). Column: Phenomenex Kinetex®, C18, 150 × 4.6 mm, 5 μm. Analytical range: 0.25–200.00 μg/mL.Results and discussion. This method was validated by selectivity, calibration curve, accuracy, precision, spike recovery, the lower limit of quantification, carry-over effect and stability.Conclusion. We developed and validated the method of quantitative determination of favipiravir in human plasma by HPLC-UV. The analytical range was 0.25–200.00 μg/mL in human plasma. The method could be applied in pharmacokinetics studies of favipiravir.

Introduction. Due to increase in the frequency of detecting cases of tuberculosis caused by strains of mycobacteria with resistance not only to traditional, but also recently introduced into clinical circulation anti-tuberculosis drugs, it is urgent to search for and develop new drugs that can be effective against multidrug-resistant (MDR-TB) and extensively drug resistant (XDR-TB) strains. One of the most promising classes of such compounds are fluorine derivatives of benzothiazinones, and particularly compound PBTZ169 (INN macozinone). This antibiotic has a high specificity against mycobacteria tuberculosis (M. tuberculosis), inhibiting one of the key enzymes of cell wall synthesis. However, macozinone as an active pharmaceutical ingredient has significant features of physical and chemical properties that hinder the development of oral dosage forms based on it. It is classified as class IV by BCS and is characterized by a very low solubility and lipophilicity, a pronounced dependence of dissolution rate on the pH of the medium, and very low bioavailability when taken orally.Aim. To substantiate the target profile, critical quality attributes and to develop a prototype of an oral dosage form with modified release of macozinone, allowing to maximize its pharmacological activity.Materials and methods. Using pharmaceutical substance macozinone hydrochloride and various excipients, experimental tablets with a dosage of 500 mg macozinone were developed. The influence of the composition of the media and the added excipients on the solubility of macozinone in various biorelevant media, the degree of swelling in the liquid and the degree of mucoadhesion of the experimental tablets to the mucus of the pig stomach were evaluated. The HPLC method was used to evaluate the kinetics of the release of the active substance.Results and discussion. In this work, the expediency of creating macozinone-containing gastro-retentive dosage forms with a slow release of the active substance, the delay mechanism of which is provided by swelling and increased adhesion to the gastric mucosa, has been substantiated. Various tablet samples were experimentally tested in which the modification of the release of the active substance and the degree of swelling and mucoadhesion were varied by introducing various excipients into the formulations, including known swelling and bioadhesive matrix agents.Conclusion. According to the results of the experiments, samples of high-dose (500 mg) swellable and mucoadhesive tablets created by the technology of two-stage granulation with the inclusion of macozinone - hydroxypropyl-beta-cyclodextrin mixtures in the primary granules and introduction of combinations of soluble and insoluble hydrophilic matrix agents into the intergranular space were recognized as the most promising for subsequent pharmacokinetic studies.

Introduction. Lappaconitine is an alkaloid, contained into Aconitum leucostomum Vorosh. roots and herbs. The alkaloid is indicated to arrhythmia. The lappaconitine drugs are metabolized into eight pharmacologically active substances, but N-desacetyllappaconitine is the most effective. Drugs based on a lappaconitine has narrow therapeutic range and many kinds of side effects. Pharmacokinetics of lappaconitine should be more studied for safety medical use of lappaconitine drugs.Aim. The aim of this study is to develop method for the quantitative determination of lappaconitine and its active metabolite N-desacetyllappaconitine in human plasma and blood by high performance liquid chromatography and tandem mass spectrometry (HPLC-MS/MS). Materials and methods. Determination of lappaconitine and N-desacetyllappaconitine in plasma and blood was carried out by HPLC-MS/MS. The samples were processed by acetonitrile protein precipitation.Results and discussion. This method was validated by next parameters: selectivity, matrix effect, calibration curve, accuracy, precision, spike recovery, lower limit of quantification, carry-over effect and stability.Conclusion. The method of the quantitative determination of lappaconitine and N-desacetyllappaconitine in human plasma and blood was developed and validated by HPLC-MS/MS. The analytical range of the was 0.50-50.00 ng/ml for lappaconitine and 0.50-100.00 ng/ml for N-desacetyllappaconitine in biological matrix. Method could be applied to determination of lappaconitine and N-desacetyllappaconitine for PK studies.

Introduction. Tranexamic acid is one of the most common drugs used to stop bleeding after trauma, in surgery and gynecology. The most common analytical method for the determination of this compound is reversed-phase high-performance liquid chromatography (HPLC). However, this compound belongs to the group of so-called poorly retained compounds due to its chemical structure. It is necessary to develop an analytical method that will allow the determination of tranexamic acid in human blood plasma with the least time, resource costs and without the use of specialized columns.Aim. The aim of this study is to develop a method for tranexamic acid in human plasma by high performance liquid chromatography with tandem mass-spectrometry (HPLC-MS/MS) for pharmacokinetic studies.Materials and methods. Determination of tranexamic acid in plasma by HPLC-MS/MS. The samples were processed by acetonitrile protein precipitation.Results and discussion. This method was validated by next parameters: selectivity, matrix effect, calibration curve, accuracy, precision, recovery, lower limit of quantification, carry-over effect and stability.Conclusion. The method of the determination of tranexamic acid in human plasma was developed and validated by HPLC-MS/MS. The linearity in plasma sample was achieved in the concentration range of 100.00–15000.00 ng/ml. Method could be applied to tranexamic acid determination in plasma for pharmacokinetics and bioequivalence studies.

Introduction. Currently, physicochemical methods of quantification are actively used to determine the content of drugs in biological fluids. High-performance liquid chromatography with various detection methods is particularly widespread. One of the most difficult practical tasks is the chromatographic separation of so-called poorly retained compounds – drug substances poorly retained on the chromatographic column. Valganciclovir and Ganciclovir are among such substances. Aim. The aim of this study is to develop a method for valganciclovir and ganciclovir in human plasma by high performance liquid chromatography with tandem mass-spectrometry (HPLC-MS/MS) for pharmacokinetic studies.Materials and methods. Determination of valganciclovir and ganciclovir in plasma by HPLC-MS/MS. The samples were processed by acetonitrile protein precipitation.Results and discussion. This method was validated by next parameters: selectivity, matrix effect, calibration curve, accuracy, precision, recovery, lower limit of quantification, carry-over and stability.Conclusion. The method of the determination of valganciclovir and ganciclovir in human plasma was developed and validated by HPLC-MS/MS. The linearity in plasma sample was achieved in the concentration range of 5.00–1000.00 ng/ml for valganciclovir and 50.00–10000.00 ng/ml for ganciclovir. Method could be applied to valganciclovir and ganciclovir determination in plasma for PK and BE studies.

Introduction. Cancer is one of the most serious and common diseases with a high level of mortality. Due to this reason the searching of new directions and methods of cancer treatment is becoming more and more important with each passing year. Significant advances in cancer immunotherapy have been reached over the past few decades. Moreover, an inhibition of the interaction between the programmed cell death receptor (PD-1) and its ligand (PD-L1), is sure to be perspective direction of the immuno-oncological therapy development.Text. PD-1/PD-L1 interaction plays a pivotal role in negative regulation of immune system, that protects host’s cells and tissues from the excessive immune response. However, it is also used by tumor cells to avoid the host's immune system. The discovery of this mechanism led to the development of inhibiting PD-1 or PD-L1 agents that enhance anti-tumor immunity. Meanwhile, anti-PD-L1 agents provide less toxicity in comparison with anti-PD-1 agents. FDA currently approved Atesolizumab, Durvalumab, and Avelumab PD-L1 inhibitors for cancer treatment. These agents demonstrated effective response during the clinical trials, however, they are used for a limited number of oncological diseases. In addition, BMS-936559 is a promising agent that had passed the first stage of the clinical trials. Nevertheless, immunotherapy involving PD-L1 inhibitors is closely related to a vast number of severe side effects including immune-mediated effects caused by the inhibition of PD-L1 ligands located on healthy cells. In these terms, the development of new agents deprived of these disadvantages is the reason for further studies.Conclusion. Immunotherapy in cancer uncovers new perspectives in treatment of refractory to standard therapies forms of cancer. And the development of new and improvement of existing PD-L1 blocking agents are of great importance in fighting against tumoral diseases.

Introduction. B-cell malignancies of the plasma cell leads to the second most spread hematological malignancy disease, called multiple myeloma. Pomalidomide is used in case of previous multiple myeloma ineffective treatment. Pomalidomide is a thalidomide synthetic derived, approved as immunomodulatory drug by the Food and Drug Administration (FDA). Nowadays, detection of pomalidomide in blood plasma by high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) is not spread. Moreover, the detection and the experimental setting accumulated data are varying greatly. This investigation provides development and validation of pomalidomide aiming to determine human blood plasma by HPLC-MS/MS method. The samples were processed by methanol protein precipitation.Aim. The aim of this study is to develop a method for the pomalidomide in human plasma by HPLC-MS/MS for pharmacokinetic studies.Materials and methods. Determination of pomalidomide in plasma by HPLC-MS/MS. The samples were processed by methanol protein precipitation.Results and discussion. This method was validated by next parameters: selectivity, matrix effect, calibration curve, accuracy, precision, spike recovery, lower limit of quantification, detection limit, carry-over and stability. Conclusion. The method of the determination of pomalidomide in human plasma was developed and validated by HPLC-MS/MS. The linearity in plasma sample was achieved in the concentration range of 1,00 – 500,00 ng/ml. Method could be applied to pomalidomide determination in plasma for PK and BE studies.

Introduction . The quality control of a medicinal product needs to be systematically improved in connection with a continuous increase in the requirements for the quality of medicines. When assessing the quality of substances and drugs, the most important indicators are authenticity, the content of the main substance and impurities. This makes it relevant to introduce modern physical and chemical methods of analysis into industrial practice in determining parameters such as authenticity, the content of the main substance and impurities. The choice and applicability of a particular method is possible only when conducting comparative studies on the application of a particular method to solve this problem. The method should preferably be recommended by the Pharmacopoeia, give unambiguous results, and the analysis should not be expensive and affordable. The methods chosen for comparative analysis are well known, but it should be noted that in recent years, instrument-making companies have significantly improved their instrument base and expanded their capabilities. Therefore, one of the objectives of this article is to demonstrate the capabilities of the selected methods for solving the problems of drug quality control using dalargin as an example. Aim . To develop methods for determining the authenticity of the active substance in a substance - Dalargin powder using NMR spectroscopy, IR spectrometry, and Mass spectroscopy. Conduct a comparative analysis of the applicability of the selected methods to solve the problem. Materials and methods . To determine the authenticity of the substance - the powder «Dalargin» used the methods of mass spectrometry, 13 C NMR and 1 H NMR spectrometry and IR spectrometry. Results and discussions . Methods have been developed for determining the authenticity of the test substance by NMR, IR, and mass spectrometry. A comparative study of the possibilities of the selected methods in solving the problem. Conclusions were drawn about the applicability of the NMR method not only in determining the authenticity of dalargin, but also in solving the problem of determining the content of the main substance and impurities. Conclusion . Authenticity methods have been developed in the substance - Dalargin powder by Mass, IR, and NMR spectrometry. It has been established that 1 H NMR spectrometry is a more informative method for authenticating.

Introduction. Neutropenia, which is an abnormally low concentration of neutrophils in the blood, is one of the common side effects in patients receiving radio- or chemotherapy. Neutropenia usually leads to higher risks of severe bacterial and fungal infections. Such medicines as colonystimulating factor filgrastim (and its conjugates) are used to prevent and treat neutropenia in oncology patients. Immunogenicity is a potential concern for any biological product, thus, its assessment is one of the most critical necessities during the development and registration of such products.Aim. The main aim of this study was to validate the ELISA method for anti-pegfilgrastim antibodies detection in human serum samples and to apply the validated method to pegfilgrastim drugs immunogenicity assessment.Materials and methods. To assess pegfilgrastim immunogenicity, the commercial ELISA kit «PEGylated Filgrastim (Neulasta®) ADA ELISA» was used for screening, confirmatory and titer assay. Moreover, to confirm the chosen commercial kit suits the study aims it was revalidated. The absorbance values were obtained using plate immunoassay analyzer Stat Fax 3200, plate washing was performed using an automatic twochannel plate washer.Results and discussion. The ELISA method for anti-pegfilgrastim antibodies determination in human serum samples was validated and applied to the analytical part of the comparative, multicenter, blind, randomized study of pegfilgrastim efficacy and safety in patients with breast cancer, receiving myelosuppressive chemotherapy. Human serum samples were first screened for anti-drug antibodies, then «screening positive» samples were analyzed in confirmatory assay with % inhibition calculation for each sample. The «confirmed positive» samples were further characterized in titer assay.Conclusions. The ELISA method for anti-pegfilgrastim antibodies determination in human serum samples was successfully validated and applied for pegfilgrastim drugs immunogenicity assessment.

Introduction. Viral infections are a serious problem that occurs during the use of immunosuppressants in preparation for organ transplantation and in the postoperative period. Cytomegalovirus (CMV) infection is one of the main causes of diseases in people with weakened immune systems. It has a direct impact on one’s body and makes it more likely to reject a transplanted organ. Antiviral drugs are used to treat and prevent this infectious disease. Valganciclovir is a prodrug whose active metabolite is ganciclovir. Valganciclovir is the drug of choice in the treatment of CMV infections. Currently, there are no researches on the matter of simultaneous determination of both valganciclovir and ganciclovir in human blood plasma by means of high-performance liquid chromatography (HPLC) with ultraviolet detection. This research delivers a thorough description of development and validation of a particular method for simultaneous determination of valganciclovir and ganciclovir in the plasma after sample preparation by the method of protein precipitation.Aim. The aim of this study is to develop method for the quantitative determination of valganciclovir and its active metabolite ganciclovir in human plasma by HPLC-UV for pharmacokinetic studies.Materials and methods. Quantitative determination of tadalafil in plasma by HPLC-UV. A sample was prepared using protein precipitation.Results and discussion. This method was validated by next validation parameters: selectivity, matrix effect, calibration curve, accuracy, precision, lower limit of quantification, carry-over and stability.Conclusion. The method of the quantitative determination of valganciclovir and its active metabolite ganciclovir in human plasma was developed and validated by HPLC-UV. The analytical range of the was 5,0–1000,0 ng/ml for valganciclovir and 100,0–10000,0 ng/ml for ganciclovir in plasma. Method could be applied to determination of valganciclovir and ganciclovir in plasma for PK and BE studies.

Introduction. One of the purposes of dissolution profile comparison is to establish the equivalence of dissolution profiles of the studied drug and the comparison drug.Text. According to the current regulatory documents, the main tool for quantitative confirmation of equivalence of drug release profiles is the calculation of the similarity factor (f 2). However, it does not consider the form of dissolution profiles, incomplete release of the drug substance, time correlation, and is not susceptible to the «outliers», which leads to false positive results. Special attention should be paid to the dissolution of drugs with high variability, which is not eliminated by either increasing the sample or changing the sampling scheme. If f 2 is not used, it is necessary to use model-dependent and model-independent methods that are statistically correct, and their use is sufficiently justified (difference factor f 1 , Weibull distribution function, comparison of release degrees at different time points (according to the student's t-criterion). However, these models have an empirical nature that calls into question the application of such methods. Multivariate analysis is widely discussed in the literature and can be used to compare the similarity of dissolution with the assumption that the data has a normal distribution. The most common methods for checking similarity of dissolution profiles for highly variable drugs are the Mahalanobis distance test and the bootstrap for f 2. There is a document of EMA about suitability of the Mahalanobis distance as a tool to assess the comparability of drug dissolution profiles and to a larger extent to emphasise the importance of confidence intervals to quantify the uncertainty around the point estimate of the chosen metric. The bootstrap methodology for f 2 does not provide a clear understanding of the application to dissolution profile comparison for incomplete-release drugs, particularly in biorelevant environments. The «T2EQ» function, based on the Mahalanobis distance for highly variable drugs (Hoffelder), gives undefined results in practice.Conclusion. The topic of equivalence of dissolution profiles requires discussion, since it is shown that the convergence factor is outdated and cannot be adequately applied. The use of modern methods does not have a clear regulatory confirmation by the regulatory authority. In the published scientific literature, several statistical methods have been explored and compared for their design and performance. It is necessary to develop a clear plan (decision treeы) for conducting the procedure for equivalence of dissolution profiles, employing a range of statistical methods.

Introduction . HIV infection is one of the most relevant diseases from a medical, epidemiological and social point of view. Timely diagnosis, detection and control of the disease, adequate prescription of antiretroviral therapy can sufficiently reduce the viral load on the patient's body, reduce the risk of transmission of infection. Currently, combinations of various antiretroviral drugs are increasingly being prescribed as therapy. One of the most important is combination of atazanavir and ritonavir. The most important stage for the study of pharmacokinetics, studies of comparative pharmacokinetics and bioequivalence is the development of an analytical method that allows you to determine the investigated substances in human plasma. There are currently no published methods for the determination of atazanavir and ritonavir in human plasma using high performance liquid chromatography with mass selective detection using a single quadrupole mass detector. In this article presents the development and validation of a method for the determination of atazanavir and ritonavir in blood plasma after sample preparation by the method of protein precipitation. Aim . The aim of the study is to develop a method for the quantitative determination of atazanavir and ritonavir in human plasma by HPLC with mass spectrometric detection for performing the analytical part of pharmacokinetic studies. Materials and methods . Determination of atazanavir and ritonavir in human plasma by HPLC with mass spectrometric detection. A sample was prepared using protein deposition. Results and discussion . The method was validated of selectivity, matrix effect, calibration curve, accuracy, precision, limit of quantification, carry-over effect and sample stability. Conclusion . The method of the determination of atazanavir and ritonavir in human plasma was developed and validated by HPLC-MS. The analytical range of the was 50.0–10000.0 ng/mL in plasma for atazanavir and 10.0–2500.0 ng/mL in plasma for ritonavir. Method could be applied to determination of atazanavir and ritonavir in plasma for PK and BE studies.

Introduction. Multicomponent oral drugs containing salbutamol, bromhexine, ambroxol and guaifenesin have a mucolytic, expectorant and bronchodilator effect. The development method for determination substances in biological fluids is a main procedure for performing the analytical part of pharmacokinetic studies and bioequivalence studies of multicomponent drugs. There is no published data of the determination of bromhexine, ambroxol and guaifenesin, but there a lot of published methods for divided determination analytes in a biological fluid. This study presents the development and validation of a method of the determination of salbutamol, bromhexine, ambroxol and guaifenesin in human blood plasma by high performance liquid chromatography with tandem mass spectrometric detection. A sample preparation was perfomed by solid-phase extraction. Deuterated derivatives were used as internal standards.Aim. The aim of the study is to develop a method for the quantitative determination of salbutamol, bromhexine, ambroxol and guaifenesin in human plasma by HPLC with tandem mass spectrometric detection for performing the analytical part of pharmacokinetic studies.Materials and methods. Determination of salbutamol, bromhexine, ambroxol and guaifenesin in human plasma by HPLC with tandem mass spectrometric detection. A sample was prepared using solid-phase extraction.Results and discussion. The method was validated by next validation parameters: selectivity, matrix effect, calibration curve, accuracy, precision, limit of quantification, carry-over and stability.Conclusion. The method of the determination of salbutamol, bromhexine, ambroxol and guaifenesin in human plasma was developed and validated by HPLC-MS/MS. The analytical range of the was 0.1–20 ng/mL in plasma for salbutamol, 0.25–25 ng/mL in plasma for bromhexine, 0.075–3 ng/mL in plasma for ambroxol, and 10–2000 ng/mL in plasma for guaifenesin. Method could be applied to determination of salbutamol, bromhexine, ambroxol and guaifenesin in plasma for PK and BE studies.

Introduction. Human Immunodeficiency Virus (HIV) is one of the main socially significant infection all over the world. HIV-positive patients take medical care, including antiretroviral drugs (ARVs) pharmacotherapy. Like all drugs, ARVs have lots of side effects that should be taken when prescribing drugs as part of highly active antiretroviral therapy. There are many cases when side effects of ARVs caused patients to enter the toxicology department. Therefore, the development of new methods for the analysis of ARV in biological fluids for the timely diagnosis of treatment of poisoning of this group of drugs is relevant today.Aim. The aim of this study is development of screening analysis of atazanavir, abacavir, nevirapine, ritonavir, lopinavir, zidovudine, darunavir and efavirenz in the urine to identify these drugs as possible toxicants for poisoning by high-performance liquid chromatography with tandem massselective detection (HPLC-MS/MS).Materials and methods. Identification of ARV was performed by HPLC-MS/MS. Methanol precipitation method was used as a sample preparation.Results and discussion. The optimal conditions for sample preparation, chromatographic separation, and mass-spectrometric detection were selected to determine the studied ARVs. This method was tested on urine samples from patients in the Department of Acute Poisoning and Somatopsychiatric Disorders (OOSPD) with acute ARV poisoning.Conclusion. This screening method for analyse atazanavir, abacavir, nevirapine, ritonavir, lopinavir, zidovudine, darunavir and efavirenz in human urine has been developed by HPLC-MS/MS. The developed method can be used to identify these drugs as possible toxicants in case of poisoning. The prospect for the development of the topic is the inclusion of new molecules in the method and quantitative determination of the studied ARVs.

Introduction. Bevacizumab is a monoclonal IgG1 antibody that binds to and inhibits the biologic activity of human vascular endothelial growth factor (VEGF). Bevacizumab is used as a targeted mono- or combination therapy for different solid tumors. Phase I clinical trial was performed to assess pharmacokinetics (PK) and immunogenicity of bevacizumab drugs. For this study 80 healthy male volunteers were recruited and randomized to either Avastin or RPH-001 group.Aim. To assess and compare pharmacokinetics and immunogenicity (safety) following single intravenous administration of Avastin® (manufactured by F. Hoffmann-La Roche Ltd.,Switzerland) and bevacizumab biosimilar RPH-001 (manufactured by R-Pharm Group,Russia).Materials and methods. Bevacizumab quantitation and quasi-quantitative anti-bevacizumab antibodies detection in human blood serum were carried out using photometric ELISA. Two different methods were successfully validated.Results and discussion. Bevacizumab quantitation method was validated for selectivity and specificity, calibration curve, sensitivity, accuracy and precision, minimal required dilution, dilution linearity and stability. The anti-bevacizumab antibodies detection method was validated for cut-point (with normalization factor calculation), selectivity, sensitivity, precision, drug tolerance, dilution linearity, matrix effect (in case of serum hemolysis), and stability. The validated methods were successfully applied to pharmacokinetic and immunogenicity assessment of bevacizumab drugs. Conclusion. The results of the PK-study showed that test and reference bevacizumab drugs were equivalent. Immunogenicity study did not show any evidence of anti-bevacizumab antibodies in blood serum samples.

Introduction. Tadalafil is a drug used to treat erectile dysfunction. For the quantitative determination of tadalafil in human plasma are used methods of high performance liquid chromatography with ultraviolet and tandem mass spectrometric detection, during the analytical part of pharmacokinetic studies. In the majority of the considered methods the method of liquid-liquid extraction and the method of solid-phase extraction are used, these methods are difficult and expensive. Therefore, the method of protein precipitation was considered as sample preparation. This method is simple and there is important to analysis a lot of clinical samples in bioequivalence studies.Aim. The aim of this study is to develop method for the quantitative determination of tadalafil in human plasma by HPLC-MS for the analytical part of pharmacokinetic studies.Materials and methods. Quantitative determination of tadalafil in plasma by HPLC-MS. A sample was prepared using acetonitrile protein precipitation.Results and discussion. This method was validated by next validation parameters: selectivity, matrix effect, calibration curve, accuracy, precision, lower limit of quantification, carry-over and stability.Conclusion. The method of the quantitative determination of tadalafil in human plasma was developed and validated by HPLC-MS. The analytical range of the was 5,00–1000,00 ng/ml tadalafil in plasma. Method could be applied to determination of tadalafil in plasma for PK and BE studies.

Introduction. In 2018 «Center of Pharmaceutical Analytics» LLC successfully passed the certification of quality management system for compliance with the requirements of ISO 9001: 2015 and GOST R ISO 9001-2015 «Quality Management System. Requirements». Text. Certification was conducted by the Certification Association «Russian Register» – a Russian company, which is an accredited body for certification of management systems of organizations. This article describes the program of certification audit of the «Russian Register», which includes: certification, consisting of two stages, inspection checks during the first and second year and re-certification audit during the third year before the expiration of the certificate. The structure of works on confirmation of the certificate of conformity of «Russian Register» includes field audits designed to assess the degree of compliance of the organization with the established requirements of the standard for compliance with which certification was carried out [1]. The objectives of the certification audit were: verification of compliance of the management system with the requirements of ISO 9001: 2015 (GOST R ISO 9001-2015), verification of established processes and documentation of the management system of the organization; assessment of the ability of the management system to ensure compliance with applicable legislative, regulatory and contractual requirements; assessment of the effectiveness of the management system to ensure that the goals can be achieved; identification of areas for possible improvement of the management system. The audit was conducted over two days on processes and units related to the activities of the organization. The audit confirmed the scope of certification in respect of: research work, bioanalytical studies, pharmacokinetic studies, STCR (comparative text of dissolution kinetics). The scope of the audit included verification of adequacy, compliance of activities and elements of the management system, including: production, management and support processes; policies; goals; organizational structure of management; documentation of management system, analysis of measures taken by the organization to eliminate the problem areas identified at the 1st stage of certification [2]. Conclusion. In September 2018, the analytical center was issued certificates of compliance with the requirements of GOST R ISO 9001:2015 in the certification Association «Russian Register» with the accreditation of the Federal service for accreditation of the Russian Federation (Rosaccreditation); international standard ISO 9001: 2015 in the Certification system of the Russian Register, a member of the international forum on accreditation IAF; certificate of conformity.

Literature and experimental data relevant to the decision to allow a waiver of in vivo bioequivalence (BE) testing for the approval of immediate release (IR) solid oral dosage forms containing piroxicam in the free acid form are reviewed. Piroxicam solubility and permeability, its therapeutic use and therapeutic index, pharmacokinetic properties, data related to the possibility of excipient interactions and reported BE/bioavailability (BA), and corresponding dissolution data are taken into consideration. The available data suggest that according to the current biopharmaceutics classification system (BCS) and all current guidances, piroxicam would be assigned to BCS Class II. The extent of piroxicam absorption seems not to depend on manufacturing conditions or excipients, so the risk of bio in equivalence in terms of area under the curve (AUC) is very low, but the rate of absorption (i.e., BE in terms of C max ) can be affected by the formulation. Current in vitro dissolution methods may not always reflect differences in terms of C max for BCS Class II weak acids; however, minor differences in absorption rate of piroxicam would not subject the patient to unacceptable risks: as piroxicam products may be taken before or after meals, the rate of absorption cannot be considered crucial to drug action. Therefore, a biowaiver for IR piroxicam solid oral dosage form is considered feasible, provided that (a) the test product contains only excipients, which are also present in IR solid oral drug products containing piroxicam, which have been approved in ICH or associated countries, for instance, those presented in Table 3 of this paper; (b) both the test and comparator drug products dissolve 85% in 30 min or less at pH 1.2, 4.5, and 6.8; and (c) the test product and comparator show dissolution profile similarity in pH 1.2, 4.5, and 6.8. When not all of these conditions can be fulfilled, BE of the products should be established in vivo .

Literature and experimental data relevant to the decision to allow a waiver of in vivo bioequivalence (BE) testing for the approval of immediate-release (IR) solid oral dosage forms containing ketoprofen are reviewed. Ketoprofen's solubility and permeability, its therapeutic use and therapeutic index, pharmacokinetic properties, data related to the possibility of excipient interactions, and reported BE/bioavailability (BA)/dissolution data were taken into consideration. The available data suggest that according to the current Biopharmaceutics Classification System (BCS) and all current guidances, ketoprofen is a weak acid that would be assigned to BCS Class II. The extent of ketoprofen absorption seems not to depend on formulation or excipients, so the risk of bioinequivalence in terms of area under the curve is very low, but the rate of absorption (i.e., BE in terms of peak plasma concentration, C(max) ) can be altered by formulation. Current in vitro dissolution methods may not always reflect differences in terms of C(max) for BCS Class II weak acids; however, such differences in absorption rate are acceptable for ketoprofen with respect to patient risks. As ketoprofen products may be taken before or after meals, the rate of absorption cannot be considered crucial to drug action. Therefore, a biowaiver for IR ketoprofen solid oral dosage form is considered feasible, provided that (a) the test product contains only excipients present also in IR solid oral drug products containing ketoprofen, which are approved in International Conference on Harmonisation or associated countries, for instance, as presented in this paper; (b) both the test drug product and the comparator dissolve 85% in 30 min or less in pH 6.8 buffer; and (c) test product and comparator show dissolution profile similarity in pH 1.2, 4.5, and 6.8. When one or more of these conditions are not fulfilled, BE should be established in vivo.

This paper describes the evaluation of the in vitro equivalence of capsules containing a BCS Class II compound, k etoprofen, marketed in Russia under biowaiver conditions and the innovator product. The in vitro equivalence test was carried out according to WHO Technical Report Series, No. 937, Annex 8. Dissolution profiles of test and reference (innovator) ketoprofen capsules are considered equivalent at pH 6.8 without statistical treatment, equivalent at pH 4.5 (f1 = 3 and f2 = 80), and not equivalent at pH 1.2 (f1 = 22 and f2 = 41). Generally, the evaluated capsules did not meet biowaiver criteria for drugs containing BCS Class II API, possibly due to the effect of surfactant (sodium lauryl sulfate) contained in the test preparation on the solubility.

The current paper is devoted to in vitro dissolution kinetics studies of amlodipine tablets marketed in Russia under biowaiver conditions. Dissolution kinetics studies were carried out according to WHO Guidance. Dissolution profiles of test and reference (innovator) amlodipine tablets were considered equivalent. INTRODUCTION Over the past three decades, dissolution testing has evolved into a powerful tool for characterizing the quality of oral pharmaceutical products. For some solid dosage forms containing active pharmaceutical ingredients with special properties, a comparative in vitro dissolution profile similarity can be used to establish equivalence of test with reference product. Such studies, used to approve equivalence other than through in vivo equivalence testing, are called “biowaiver” (1). Amlodipine is a dihydropyridine calcium antagonist (calcium ion antagonist or slow-channel blocker) that inhibits the transmembrane influx of calcium ions into vascular smooth muscle and cardiac muscle. It is indicated for the treatment of hypertension, chronic stable angina, and confirmed or suspected vasospastic angina (2). The chemical name of amlodipine is 3-ethyl 5-methyl 2-[(2aminoethoxy)methyl]-4-(2-chlorophenyl)-6-methyl-1,4dihydropyridine-3,5-dicarboxylate. Its structure is shown in Figure 1. Solubility Amlodipine is described as slightly soluble in water in different Pharmacopoeias (3, 4). The experimental water solubility for amlodipine is 75.3 mg/L (5). The lowest solubility in the pH range from 1 to 6.8 at 37 °C is 1 mg/mL (1). Within the gastrointestinal pH range, amlodipine is an ionized compound (weak base) (5). The pKa of amlodipine is about 8.6 at 25 °C (5). Dosage form strength is expressed in mg of salt and is not equivalent to the free base. Amlodipine is listed in the WHO Model list of medicines as an antihypertensive medicine in a 5-mg tablet strength (6). Russia has Marketing Authorizations for amlodipine as an immediate-release dosage form in strengths of 2.5; 5, and 10 mg (7). Thus the D/S ratio for the amlodipine WHO Model List of Essential Medicines dose (5 mg) at a pH range of 1.2–6.8 is 5 mL and 10 mL for the highest dose marketed in Russia. Therefore, amlodipine is a “highly soluble” drug according to WHO Guidance (D/S ratio ≤ 250 mL). Permeability When an active pharmaceutical ingredient is absorbed to an extent of 85% or more, it is considered “highly permeable.” Amlodipine’s absolute bioavailability is 60–65%, but its permeability is classified as “high” due to metabolite excretion in urine (90–95%). Taking amlodipine solubility and permeability into account, according to WHO Guidances, amlodipine is assigned to BCS Class I (1). Thus, amlodipine in vitro equivalence may be evaluated under biowaiver conditions for BCS Class I (1). MATERIALS AND METHODS Chemicals Analytical grade concentrated hydrochloric acid, glacial acetic acid, potassium dihydrophosphate, disodium hydrophosphate dodecahydrate, and potassium chloride were used. e-mail: ramenskaia@mail.ru *Corresponding author. Figure 1. Structure of amlodipine. diss-17-03-04.indd 20 8/18/2010 1:42:43 PM dx.doi.org/10.14227/DT170310P20