Methodical approaches to bioassay of substances containing unstable functional groups

This article describes the method development approaches for bioassay of substances containing unstable functional groups and forming unstable metabolites using the example of mycophenolic acid, methyldopa and mebeverine metabolite

APPROACHES TO THE DEVELOPMENT OF BIOANALYTICAL METHODS FOR DETERMINATION OF UNSTABLE SUBSTANCES IN BIOLOGICAL FLUIDS

The approaches to bioanalytical method development for determination of substances which contain unstable functional groups in the structure are described. The oxidation and the hydrolysis are main causes of the decomposition of substances in biological fluids. Phenolic hydroxyls contain drugs were selected as examples of oxidable compounds, glucuronides of drugs were selected as examples of hydrolysable compounds. Determination of mycophenolic acid, which contains one phenolic hydroxyl and metabolized by formation of glucuronides, in plasma was performed using high performance liquid chromatography with mass-spectrometry and tandem mass-spectrometry detection. Methyldopa, which contains two phenolic hydroxyls, in stabilized plasma was assayed by high performance liquid chromatography – tandem mass-spectrometry in the range of 0.02–3.00 μg/ml. Concentrations of desmethyl mebeverine acid, which contains in the structure one phenolic hydroxyl and metabolized by formation of phenolic glucuronide, was measured simultaneously with mebeverine acid in the range of 10–2000 ng/ml. The influence of the ion source conversion of glucuronides on the quantitative determination of the substances was studied in the initial part of methods development. The next, selection of anticoagulants based on the study of short-term stability and freeze/thaw stability of the analytes and back conversion of their glucuronides was performed. The combination of anticoagulant K3EDTA and the antioxidant solution containing a mixture of ascorbic acid, sodium sulfite and sodium hydrogen carbonate in the concentrations of 5.0 %, 0.2 % and 2.4 %, respectively, was used to prevent degradation of methyldopa

Enzyme-Linked Immunosorbent Assay Method Application in the Study of Comparative Pharmacokinetics of Insulin Glargin Preparations

Aims: adaptation and validation of the ELISA method insulin glargine determination for the pharmacokinetic study, practical approval in the biosimilars clinical trial.Materials and methods. Serum insulin glargine determination was measured using a commercial ELISA kit. All tests were run on a Personal LAB machine (Adaltis S.r.l., Rome, Italy) with test systems for measuring the concentration of insulin glargine (Invitron Ltd., United Kingdom); human insulin concentrations were measured in the samples from the study for correction of cross-reactivity. Clinical part of this study included 42 male patients aged 18–65 with diabetes mellitus type 1. This was a double-blind, randomized, crossover clamp study with wash-out period of 7–14 days. Comparisons drugs: Insulin Glargine (glargine) solution for subcutaneous administration, 100 U/ml (GEROPHARM, Russia) and Lantus® (glargine) solution for subcutaneous administration, 100 U/ml (Sanofi-Aventis Deutschland GmbH, Germany).Results. At the stage of the method adaptation the modification of original manufacturer’s method was performed; the full validation of modified analytical method for all parameters (selectivity, specificity, precision of calibration curves, intra- and inter-batch precision and accuracy, carry-over, dilution integrity, stability of solutions, stability in biologic matrix, parallelism) in accordance with regulatory authorities requirements has been done. The primary endpoint for long-acting insulins – AUCins.0-τ was calculated. Insulin Glargine and Lantus® are equivalent based on AUCins.0-τ data (point estimation for ratio of geometric means was 99 %, the confidence intervals for the ratio of the geometric mean for AUCins.0-τ was 81.02–120.62 %, that correspond to acceptance range 80.00–125.00 %)

Исследование сравнительной фармакокинетики таблетированных форм микофеноловой кислоты

In a single-dose, two-treatment, two-period, two-sequence crossover study with a 14-days washout period was carried out the bioequivalence study of two tablet coated formulation of mycophenolic acid that given to 48 volunteers in equal doses (dosage 360 mg). There were calculated the followed parameters: AUC0-t, Cmax, Tmax, Cmax/AUC. 90% confidence interval for ratio of geometric mean AUC0-t values was 98,97% - 111,49% and one for ratio of geometric mean Cmax was 121,27% - 153,94%. The upper limit of the confidence interval of Cmax valuesa goes beyond the permissible range according to the protocol study (75-133%). It is not possible to state bioequivalence of drugs. Possible causes of discrepancies of pharmacokinetic parameters were analyzed.В рамках открытого, рандомизированного, перекрёстного исследования с 14-дневным периодом отмывки, с двумя последовательностями была изучена биоэквивалентность двух таблетированных форм микофеноловой кислоты на 48 добровольцах (дозировка 360 мг). Для анализируемых препаратов рассчитаны следующие фармакокинетические параметры: AUC0-t, Cmax, Tmax, Cmax/AUC. 90% доверительные интервалы для отношения геометрических средних значений параметров AUC0-t и Cmax микофеноловой кислоты составили 98,97-111,49% и 121,27-153,94% соответственно. Верхняя граница доверительного интервала, соответствующего параметру Cmax, выходит за рамки допустимого согласно протоколу исследования диапазона (75-133%), что не позволило констатировать биоэквивалентность исследуемых препаратов. Также были проанализированы возможные причины расхождений фармакокинетических параметров

Исследование фармакокинетики мебеверина в форме капсул с пролонгированным высвобождением

Pharmacokinetic study of prolonged release capsules of mebeverine was carried out on 24 volunteers. It is known that the drug substance is completely metabolized due to first-pass effect. Therefore, pharmacokinetic parameters of the main metabolites -mebeverine acid and desmethyl mebeverine acid were measured. Bioanalytical method was developed to measurement of concentrations of these metabolites in blood plasma by using HPLC-MS/MS.Было проведено исследование фармакокинетики мебеверина в форме капсул с пролонгированным высвобождением на 24 здоровых добровольцах. Известно, что данное лекарственное вещество полностью метаболизируется на пресистемном этапе. Поэтому измерялись фармакокинетические параметры только его основных метаболитов - мебевериновой кислоты и деметилированной мебевериновой кислоты. Для определения концентрации данных метаболитов в плазме крови разработана биоаналитическая методика с использованием высокоэффективной жидкостной хроматографии с масс-спектрометрическим детектированием

Изучение влияния приёма пищи на биодоступность, безопасность и переносимость лекарственного препарата Атериксен®, таблетки, 100 мг у здоровых добровольцев

The aim. The primary objective of the study was to evaluate the effect of food on the bioavailability of Aterixen® 100 mg tablet after single oral dose under fasting or fed conditions. The secondary objective was to evaluate the pharmacokinetic parameters, safety, and tolerability of Aterixen® 100 mg tablet after single oral dose under fasting or fed conditions. Materials and methods. Healthy male and female volunteers aged 18 to 45 years were included in the study. Due to lack of data about intra-individual variability of the main pharmacokinetic parameters of the active substance in Aterixen® (XC221GI, 1-[2-(1-Methylimidazol-4-yl)-ethyl]perhydroazin-2,6-dione), an adaptive group sequential approach was used in the study. At Stage I, 24 volunteers were randomized into 2 groups (12 in each group): Group 1 (sequence AAB) received treatment A (administration of the drug under fasting conditions) during period I, treatment A during period II and treatment B (administration of the drug under fed conditions) during period III, Group 2 (sequence BBA) received therapy B during period I, therapy B during period II, and therapy A during period III. In each study period, serial blood samples were collected before and throughout 12 h after administration of the study drug. The quantification of the active substance XC221GI in plasma samples was performed using a validated high-performance liquid chromatography method with mass spectrometric detection. Safety evaluation was performed on the basis of frequency and severity of adverse events (AEs) and serious adverse events (SAEs), which were registered based on complaints, physical examination, laboratory tests, and electrocardiography (ECG). Drug tolerability was evaluated in terms of proportion of volunteers who prematurely discontinued participation in the study due to AE/SAE. Results. 24 randomized volunteers completed the study in compliance with the approved study protocol. The averaged pharmacokinetic curves profiles of XC221GI had similar shapes under fasting and fed conditions. Confidence intervals for the ratio of the geometric means for the primary parameters (AUC(0-t) and Cmax) of XC221GI and AUC(0-∞) were within the 80-125 % acceptance interval, while a small in absolute value, but statistically significant differences were noted in time until Cmax is reached. Throughout the study, 2 volunteers reported AEs (low RBC count, low hemoglobin concentration, and low hematocrit value) after receiving the study drug under fed conditions. All reported AEs were mild. The relationship between AEs and the study drug product was assessed by investigator as doubtful. Conclusion. The results of this study indicate that food does not affect the bioavailability of Aterixen® 100 mg, tablets, and the single oral dose of 100 mg was safe and well tolerated by healthy volunteers.Цель исследования. Первичной целью исследования являлась оценка влияния приёма пищи на биодоступность лекарственного препарата Атериксен®, таблетки, 100 мг после его однократного приёма натощак и после еды. Дополнительная цель заключалась в оценке фармакокинетических параметров, безопасности и переносимости препарата Атериксен® при его однократном приёме в дозе 100 мг натощак и после приёма пищи. Материал и методы. В исследование включали здоровых добровольцев мужского и женского пола в возрасте от 18 до 45 лет. В связи с отсутствием данных о внутрииндивидуальной вариабельности основных фармакокинетических параметров действующего вещества препарата Атериксен® (XC221GI, 1-[2-(1-Метилимидазол-4-ил)-этил]пергидроазин-2,6-дион) в исследовании применялся адаптивный последовательный подход. На Этапе I было рандомизировано 24 добровольца (по 12 в каждой группе): группа 1 (последовательность ААВ) принимала терапию А (приём препарата натощак) в периоде I, терапию А в периоде II и терапию В (приём препарата после еды) в периоде III, группа 2 (последовательность ВВА) принимала терапию В в периоде I, терапию В в периоде II и терапию А в периоде III. В каждом периоде исследования у добровольцев отбирали образцы крови до и в течение 12 ч после приёма препарата исследования. Количественное определение действующего вещества XC221GI в образцах плазмы крови проводилось валидированным методом высокоэффективной жидкостной хроматографии с масс-спектрометрическим детектированием. Безопасность препарата оценивали по количеству и степени тяжести нежелательных явлений (НЯ) и серьёзных нежелательных явлений (СНЯ), зарегистрированных на основании жалоб, данных физикального осмотра, а также по изменениям лабораторных показателей и электрокардиографического исследования (ЭКГ). Переносимость исследуемого препарата оценивали по доле добровольцев, досрочно прекративших участие в исследовании из-за возникновения НЯ/СНЯ. Результаты исследования. 24 рандомизированных добровольца завершили исследование полностью в соответствии с одобренным протоколом исследования. Усреднённые профили фармакокинетических кривых XC221GI при приёме исследуемого препарата натощак и после приёма пищи имели близкие формы. Доверительные интервалы для отношений средних геометрических значений первичных показателей (AUC(0-t) и Cmax) XC221GI, а также AUC(0-∞) соответствовали пределам эквивалентности 80,00–125,00 %, при этом было отмечено небольшое по абсолютной величине, но статистически значимое различие по времени достижения максимальной концентрации исследуемого вещества. На протяжении исследования у 2 добровольцев при приёме препарата после приёма пищи отмечались НЯ в виде снижения количества эритроцитов, концентрации гемоглобина и значения гематокрита. Все зарегистрированные НЯ имели лёгкую степень тяжести. Связь НЯ с исследуемым препаратом по оценке врача-исследователя была расценена как сомнительная. Заключение. Результаты исследования показали отсутствие влияния фактора приёма пищи на биодоступность лекарственного препарата Атериксен®, таблетки, 100 мг, а также его безопасность и хорошую переносимость при однократном приёме здоровыми добровольцами в дозе 100 мг

Methodical approaches to bioassay of substances containing unstable functional groups

This article describes the method development approaches for bioassay of substances containing unstable functional groups and forming unstable metabolites using the example of mycophenolic acid, methyldopa and mebeverine metabolite

Pharmacokinetic and Bioequivalence Study of Telzap AM^® (Telmisartan/amlodipine Fixed-dose Combination) and Coadministered Mikardis^® (Telmisartan) and Norvask^® (Amlodipine) in Healthy Subjects

Introduction. A fixed dose combination of telmisartan and amlodipine is widely used in clinical practice during hypertension treatment. Combination of telmisartan and amlodipine demonstrates potentiating synergistic effect on blood pressure decrease. A bioequivalence study of Telzap® AM with coadministered Mikardis® and Norvask® was conducted with 60 volunteers.Aim. The purpose of the bioequivalence trial was a comparative study of the pharmacokinetics and evidence of the bioequivalence of the fixed dose combination drug product Telzap® AM (telmisartan + amlodipine, tablets, 80 + 10 mg, Zentiva ks company, Czech Republic) and coadministrated monocomponent drug products Mikardis® (telmisartan, tablets 80 mg, Beringer Ingelheim International GmbH, Germany) and Norvask® [amlodipine, tablets 10 mg, Pfizer HCP Corporation (USA), Russia] in healthy volunteers after a single administration under fasting.Materials and methods. To prove bioequivalence, an open label, comparative, randomized, crossover four-period replicate clinical trial was conducted. The concentrations of amlodipine and telmisartan in plasma samples were determined by a validated HPLC-MS/MS method. A pharmacokinetic and statistical analysis was performed and confidence intervals for the pharmacokinetic parameters Cmax and AUC0-72 were calculated.Results and discussion. It can be concluded that the studied formulations are bioequivalent in terms of pharmacokinetic parameters of amlodipine and telmisartan. All 90 % confidence intervals for the estimated pharmacokinetic parameters of amlodipine were in the range of 80–125 %, 90 % confidence intervals for telmisartan were within the bioequivalence range of 80–125 % for AUC0-72, and 76.73–130.32 % for Cmax.Conclusion. Thus, according to the criteria used in the study, the formulations are proved to be bioequivalent