Chromatographic study of sitagliptin and ertugliflozin under quality-by-design paradigm

Abstract The present study entails the systematic development and validation of a stability-indicating RP-HPLC method for the analysis of sitagliptin and ertugliflozin in a fixed-dose combination. Analytical quality by design (AQbD) concepts were used to define critical method variables, employing Pareto risk assessment and a Placket-Burman screening design, preceded by a Box-Behnken design with response surface analysis to optimise critical method parameters such as % acetonitrile (X1), buffer pH (X2) and column oven temperature (X3). Multiple response optimisation (Derringer's desirability) of variables was accomplished by studying critical analytical attributes, such as resolution, retention time and theoretical plates. The title analytes were separated effectively on a PRONTOSIL C18 column at 37 °C using a mobile phase of acetonitrile:acetate buffer, pH 4.4 (36:64 percent v/v), pumped at a flow rate of 1 mL/min, and UV detection at 225 nm. Linearity was observed over a concentration range of 25-150 µg/mL and 3.75-22.5 µg/mL at retention times of 2.82 and 3.92 min for sitagliptin and ertugliflozin, respectively. The method obeyed all validation parameters of the ICH Q2(R1) guidelines. The proposed robust method allows the study of the selected drugs in pharmaceutical dosage forms as well as in drug stability studies under various stress conditions.

Novel Eco-Friendly Stability Indicating Capillary Zone Electrophoresis Method for Determination of Aripiprazole in Tablet Dosage form: DoE Directed Optimization, Development and Method Validation.

In this work, a novel environment-friendly stability indicating capillary zone electrophoresis (CZE) method has been developed and validated for assaying the aripiprazole (ARP) in tablet dosage form. The separation of ARP from its degradation products and internal standard was achieved using a fused silica capillary column (30.2 cm x 75 µm ID), a background electrolyte containing 6 mmol L-1 ammonium formate buffer (pH 3) with 5% methanol under a potential of 15 kV and detection at 214 nm. The stability indicating ability of the method was investigated by analyzing ARP after being subjected to acidic, alkaline, thermal, photolytic, and oxidative stress conditions, according to ICH guidelines. Design of experiments was used during forced degradation and method optimization. Oxidation was the main degradation pathway among those evaluated. The drug was separated from its oxidative degradation products in less than 4 min. CZE method was linear between 60 - 140 µg mL-1, R2 = 0.9980, precise (intra-day 0.88% and inter-day 1.30%). The average recovery was 100.93 ± 0.77%. This is the first method in the literature for quantification of ARP in the presence of its related degradation products with high separation efficiency, low operation cost and minimum solvent consumption. This method could be helpful in the routine quality control analysis in the pharmaceutical industries with least harmful effect on the environment. CZE is considered an eco-friendly alternative of conventionally HPLC methods.

Stability Indicating Methods for Determination of Third Generation Antiepileptic Drugs and Their Related Substances.

The third generation of antiepileptic drugs that have been approved by international regulatory agencies between 2007 and 2018 include rufinamide, stiripentol, eslicarbazepine acetate, lacosamide, perampanel, brivaracetam and everolimus. As part of demonstrating their safety profile, stability indicating methods are developed to monitor these drugs and their impurities. In this context, this review describe some characteristics, impurities and the stability indicating methods used for the determination of these drugs and the presence of their related substances. Through a search in official compendia and scientific articles, fifty-six analytical methodologies were identified up to October 2020. The methodologies were developed using techniques of HPLC, UPLC, HPTLC, GC and UV/Vis spectrophotometry. A majority of the methods (∼70%) employed HPLC-UV. A number of these antiepileptic drugs were found to have had a small number of studies related to their stability and for the detection of impurities. The presentation of the current level of research on third generation antiepileptic drugs highlights the need for new stability and safety studies that are necessary to develop new pharmaceutical products containing these drugs.

Stability indicating Rp-UPLC method development and validation for the simultaneous estimation of fosnetupitant and palonosetron in bulk and injection dosage form

Abstract A stability indicating UPLC method has been developed and validated for the simultaneous determination of fosnetupitant and palonosetron in bulk and in injection dosage form. This combination is used for the prevention of acute and delayed nausea and vomiting associated with initial and repeated courses of highly emetogenic chemotherapy for cancer. The chromatographic analysis was performed on an HSS, RP C18 column (2.1 x 100 mm, 1.8 µm) with an isocratic mobile phase composed of 0.25 M potassium dihydrogen orthophosphate buffer (pH 6.5), pH adjusted with dilute sodium hydroxide:acetonitrile (55:45 v/v), at a flow rate of 0.5 mL/min, and the eluents were monitored at an isosbestic point of 286 nm. The developed method was validated according to the ICH guidelines pertaining to specificity, precision, accuracy, linearity and robustness, and the stability indicating nature of the method was established by forced degradation studies. The retention times of fosnetupitant and palonosetron were observed at 1.390 and 2.404 min, respectively. The developed method proved to be accurate and precise. Linearity was established between 4.70 and 14.10 µg/mL for fosnetupitant and between 0.05 and 0.15 µg/mL for palonosetron. The LOD and LOQ were 0.115 and 0.385 µg/mL, respectively, for fosnetupitant, and 0.005 and 0.016 µg/mL, respectively, for palonosetron. Therefore, the proposed UPLC method was reliable, reproducible, precise and sensitive for the quantification of fosnetupitant and palonosetron.

Stability-indicating method development for quantification of bromopride, its impurities, and degradation products by ultra-high performance liquid chromatography applying Analytical Quality by Design principles.

A comprehensive forced degradation study for bromopride was carried out in accordance with International Conference on Harmonization (ICH) recommendations followed by the identification and prospecting of the major degradation products. The analytical quality by design (AQbD) concepts were used to develop a stability-indicating method for bromopride and five organic impurities quantitation by ultra-high performance liquid chromatography with UV detection (UHPLC-UV). Two screenings and one optimization design were performed, including a Monte Carlo simulation to assess the Method Operable Design Region (MODR). The AQbD approach provided a high degree of method understanding in a very short period of time, less than two weeks, and the validated MODR provided information on robust analytical conditions contributing to the assignment of suitable control strategies.

Luliconazole: Stability-indicating LC method, structural elucidation of major degradation product by HRMS and in silico studies / Luliconazol: método por LC indicativo de estabilidad, elucidación estructural del producto de degradación mayoritario por HRMS y estudios in silico / Luliconazol: método LC indicativo de estabilidade, elucidação estrutural do principal produto de degradação por HRMS e estudos in sílico

SUMMARY Aim: A new stability-indicating liquid chromatography method was developed and validated for the quantitative determination of luliconazole. Materials and methods: Preliminary forced degradation study demonstrated an additional peak of the degradation product at the same retention time to the drug, due to this, the method was developed optimizing the chromatographic conditions to provide sufficient peak resolution (R ≥ 2). The experimental design was evaluated to assess the robustness and the best chromatographic conditions to be used for the validation. Methodology: Luliconazole solutions were exposed to various stress conditions to evaluate the method indication stability, in which the degradation product (DP-1) formed was isolated, identified, and evaluated in silico to predict degradation pathway and toxicity. The procedure was validated by robustness, selectivity, linearity, precision, and accuracy. Liquid chromatography was performed in a Phenomenex® RP-18 column with a mixture of acetonitrile and 0.3% (v/v) triethylamine solution as a mobile phase in isocratic elution. Results and conclusions: The method demonstrated robustness, good recovery, precision, linear response over a range from 5.0 to 40.0 μg.mL-1- and to be stability indicating. The alkaline stress condition resulted in the formation of DP-1. HRMS studies identified this product as an hydroxyacetamide derivative, and in silico studies did not show toxic potential.

RESUMEN Objetivo: Un nuevo método indicativo de estabilidad por cromatografía líquida fue desarrollado y validado para la determinación cuantitativa de luliconazol. Materiales y métodos: Estudios preliminares de degradación forzada demostraron un pico adicional en el mismo tiempo de retención del fármaco. El método desarrollado para optimizar las condiciones cromatográicas proporcionó una adecuada resolución (R ≥ 2). El diseño experimental fue evaluado para verificar su robustez y la mejor condición cromatográica para validación. Metodología: Las soluciones de luliconazol fueron expuestas a diferentes condiciones de estrés para evaluar la indicación de estabilidad del método, el aislamiento del producto de degradación formado (DP-1), su identificación y análisis in silico para predecir su ruta de degradación y toxicidad. El procedimiento se validó por robustez, selectividad, linealidad, precisión y exactitud. Las condiciones cromatográficas incluyeron una columna Phenomenex® RP-18, como fase móvil una mezcla de acetonitrilo y solución 0,3% (v/v) de trietilamina en elución isocrática. Resultados y conclusiones: El método mostró ser robusto, con buena recuperación, precisión, respuesta lineal en el rango de 5,0 a 40,0 μg.mL-1 e indicativo de la estabilidad. La condición de estrés alcalina resultó en la formación de DP-1. Estudios por HRMS identificaron este producto como un derivado hidroxiacetamida y los estudios in silico no mostraron potencial de toxicidad.

RESUMO Objetivo: Um novo método indicativo de estabilidade por cromatograia líquida foi desenvolvido e validado para a determinação quantitativa de luliconazol. Materiais e métodos: Estudos preliminares de degradação forçada demonstraram um pico adicional no mesmo tempo de retenção do medicamento. O método desenvolvido para otimizar as condições cromatográficas proporcionou resolução adequada (R ≥ 2). O delineamento experimental foi avaliado para verificar sua robustez e a melhor condição cromatográica para validação. Metodologia: Soluções de luliconazol foram expostas a diferentes condições de estresse para avaliar a indicação da estabilidade do método, o isolamento do produto de degradação formado (DP-1), sua identificação e análise in silico para predizer sua rota de degradação e toxicidade. O procedimento foi validado quanto à robustez, seletividade, linearidade, precisão e exatidão. As condições cromatográficas incluíram uma coluna Phenomenex® RP-18, como fase móvel uma mistura de acetonitrila e solução de trietilamina 0,3% (v/v) em eluição isocrática. Resultados e conclusões: O método mostrou-se robusto, com boa recuperação, precisão, resposta linear na faixa de 5,0 a 40,0 μg.mL-1 e indicativo de estabilidade. A condição de estresse alcalino resultou na formação de DP-1. Os estudos da HRMS identificaram este produto como um derivado da hidroxiacetamida e os estudos in silico não mostraram nenhum potencial de toxicidade.

Stability-indicating method for the novel antifungal compound RI76: Characterization and in vitro antifungal activity of its active degradation product.

RI76 is a novel 2-thiazolylhydrazone compound with reported antifungal activity. In preclinical drug development, it is fundamental to know the impurity profile and to understand degradation mechanisms of the molecule. In our study, RI76 was subjected to forced degradation conditions, and a stability-indicating HPLC-DAD method was developed and validated. Separation was carried out on a C18 column (150 × 4.6 mm i.d., 5 µm) maintained at 40°C using a 1 mL/min flow rate of 2 mM ammonium acetate with 0.1% formic acid (pH 3.0) and acetonitrile in gradient mode. The method was linear in the range of 0.7-91 µg/mL for RI76 and 0.7-25 µg/mL for its degradation product PD76. The formation of a major degradation product was quickly observed when RI76 was in aqueous solution. The chemical structure of this product, named PD76, was proposed based on LC-UV-MS experiments, synthesized in-house, and confirmed by NMR spectroscopy and chromatographic analysis. In vitro antifungal activity assays demonstrated that this resultant product shows a promising activity against clinically important Candida and Cryptococcus strains, matching or surpassing the activity of its precursor and of well-established antifungal drugs.

A stability-indicating ultra-fast liquid chromatography method for the assay of the main flavonoids of Achyrocline satureioides (Marcela) in porcine skin layers and nanoemulsions.

INTRODUCTION: Achyrocline satureioides (marcela or macela) is a plant widely used in folk medicine in South America. Recently, there has been increasing interest for the development of skin care products containing A. satureoides extracts, due to its well-documented antioxidant, antiherpetic, and wound healing properties. OBJECTIVES: The present study aimed to develop and validate a yet unexplored stability-indicating and robust ultra-fast liquid chromatography (UFLC) method for the simultaneous quantification of the main flavonoids of A. satureioides in extracts, nanoemulsions, and porcine skin layers. MATERIAL AND METHODS: The chromatographic separation of flavonoids quercetin, luteolin, and 3-O-methylquercetin was performed on a Luna C18 analytical column (100 mm × 2.0 mm i.d.; particle size 2.5 µm) using isocratic elution with methanol/phosphoric acid 1% (48:52 v/v) with a flow rate of 0.3 mL/min at 40°C. RESULTS: The method was found to be specific, linear (R > 0.998), precise, accurate, and robust for all flavonoids assayed in A. satureioides extract, nanoemulsions, and porcine ear skin. A low matrix effect was noted for all complex matrices. The stability-indicating UFLC method was evaluated by submitting isolated flavonoids, a mixture of standards, and A. satureioides extract to acidic, alkaline, oxidative, UV-A/UV-C light, and thermal stress conditions. No peaks were found co-eluting with the flavonoids of interest in all matrices. The robustness of the method was confirmed using Plackett-Burman experimental design. CONCLUSION: The short run time (8 min) and reliability of the method could be useful for the determination of A. satureioides flavonoids in topical product development since extracts of this medicinal plant have been used to treat various skin disorders.

Comparative stability of arbutin in Arctostaphylos uva-ursi by a new comprehensive stability-indicating HPLC method.

INTRODUCTION: Arbutin is a phenol glucoside found in high concentrations in bearberry leaves and associated with the antimicrobial activity of the plant. Hydroquinone can also be found in leaves or be formed by degradation of arbutin. Lengthy exposure to free hydroquinone is associated with induction of toxicity in different organs. OBJECTIVE: To develop and validate a stability-indicating method by high-performance liquid chromatography diode array detector (HPLC-DAD) for simultaneous quantification of arbutin and hydroquinone in bearberry leaves and perform a comprehensive forced degradation study comparing synthetic arbutin and the arbutin in bearberry leaves. METHODS: Separation was performed using a C18 column, mobile phase with water-methanol (95:5), flow rate 1.0 mL/min and detection at 280 nm. Bearberry leaves were assayed and a forced degradation study of arbutin was performed in different conditions. RESULTS: The method complied with all required validation parameters. Contents varied from 1.19 to 4.15% (w/w) of arbutin and from 0.022 to 0.604% (w/w) of hydroquinone. Synthetic arbutin was susceptible to acid hydrolysis and oxidative degradation, forming hydroquinone as the main degradation product. The same study using bearberry leaves showed that constituents of the plant matrix may act as antioxidants, reducing the oxidative degradation of arbutin, however acid hydrolysis of arbutin occurred in higher intensity. CONCLUSION: Analysis of bearberry leaves evidenced high variation in arbutin and hydroquinone levels, demonstrating the need for standardisation and control. The stability profiles of synthetic arbutin and the arbutin in bearberry leaves were considerably different and the results may be useful for determining the most appropriate conditions for extraction and production of bearberry-based formulations.

Forced degradation studies of norepinephrine and epinephrine from dental anesthetics: Development of stability-indicating HPLC method and in silico toxicity evaluation.

Injectable solutions containing epinephrine (EPI) and norepinephrine (NE) are not stable, and their degradation is favored mainly by the oxidation of catechol moiety. As studies of these drugs under forced degradation conditions are scarce, herein, we report the identification of their degradation products (DP) in anesthetic formulations by the development of stability-indicating HPLC method. Finally, the risk assessment of the major degradation products was evaluated using in silico toxicity approach. HPLC method was developed to obtain a higher selectivity allowing adequate elution for both drugs and their DPs. The optimized conditions were developed using a C18 HPLC column, sodium 1-octanesulfonate, and methanol (80:20, v/v) as mobile phase, with a flow rate of 1.5 mL/min, UV detection at 199 nm. The analysis of standard solutions with these modifications resulted in greater retention time for EPI and NE, which allow the separation of these drugs from their respective DPs. Then, five DPs were identified and analyzed by in silico studies. Most of the DPs showed important alerts as hepatotoxicity and mutagenicity. To the best of our acknowledgment, this is the first report of a stability-indicating HPLC method that can be used with formulations containing catecholamines.

Analytical lifecycle management oriented development and validation of a new stability-indicating ultra-fast liquid chromatographic method: case study of Glycopyrrolate

A new stability-indicating liquid chromatographic method was developed and validated for the estimation of glycopyrrolate in pharmaceutical formulations. A contemporary approach to analytical life-cycle management was followed to develop a robust and reliable chromatographic method. Scouted method variables such as % methanol, the strength of tetra butyl ammonium hydrogen sulfate and mobile phase flow rate were optimized using the design of experiment approach and their effect on critical quality attributes was studied. The critical quality attributes viz. retention time, theoretical plate count and symmetry factor were highly influenced by the three critical method variables. Optimum chromatography was attained on a C-18 column with a mobile phase methanol: 10 mM tetra butyl ammonium hydrogen sulfate (80:20, v/v) flowing at 1.0 mL.min-1. Chromatographic method specificity was ensured by degrading the drug forcefully. Validation studies postulated method acceptability and suitability for estimating glycopyrrolate in both bulk as well as injection formulation. Results for parameters viz. linearity (5-250 µg.mL-1), accuracy (>99%) and precision (<2%) advocated method reliability. Overall the method was reliable and of optimum quality and, possess the potential of application in routine and bio-analytical purposes

Development and validation of a stability indicating high performance liquid chromatography method for trimethobenzamide

A simple, accurate, precise and robust stability indicating RP-HPLC assay method has been developed for the estimation of trimethobenzamide in stress sample. An isocratic separation of trimethobenzamide was achieved on Kromasil 100 C-18 column (250 X 4.6mm, 5µ) with a flow rate of 1.0 ml/min and by using a photodiode array detector to detect the analyte at 213nm. The optimized mobile phase consisted of methanol: ammonium formate (44:56, v/v). The drug was subjected to different forced degradation conditions according to ICH guidelines including acid, base, neutral hydrolysis, oxidation, photolysis and thermal degradation. Degradation products were found only in basic and oxidative degradation conditions. All the degradation products got eluted in an overall analytical run time of 12min. The developed analytical method has been validated according to the ICH guidelines. Response of trimethobenzamide was linear over the concentration range of 0.5-50µg/mL (r2 = 0.999). Accuracy was found to be in between 94.03% to 100.39%. Degradation products resulting from the stress studies did not interfere with the detection of the analyte.

Stability-indicating HPLC-DAD method for the simultaneous determination of fluoroquinolone in combination with a non-steroidal anti-inflammatory drug in pharmaceutical formulation

We developed and validated a stability-indicating assay method for the simultaneous determination of enrofloxacin and piroxicam in combination and in the presence of degradation products. Reverse-phase high-performance liquid chromatography analyses were carried out on a Vertisep C18 column and acetonitrile-water (48:52 v/v, pH 3.0) mobile phase with a 1.00 mL min−1 flow rate. The efficient chromatographic separation of these drugs and their forced degradation products was achieved in less than 5min with a peak purity match factor higher than 950. The method used showed linearity in the concentration ranges of 0.25 to 16.0 µg mL−1 for enrofloxacin (r = 0.9997) and 0.125 to 8.0 µg mL−1 for piroxicam (r = 0.9999) as well as precision (relative standard deviation lower than 2%), accuracy (mean recovery 100 ± 2%), and robustness, according to ICH (International Conference on Harmonization) and AOAC (Association of Official Analytical Chemists) guidelines. This method can simultaneously determine the combination of these drugs in a veterinary formulation and separate the drug peaks from their forced degradation products. Additionally, its optimized chromatographic conditions can contribute to the quality control of this formulation in pharmaceutical manufacturing plants and minimize waste from the organic solvent.

Stability-indicating HPLC method for determination of amiodarone hydrochloride and its impurities in tablets: a detailed forced degradation study

Resumo Amiodarone hydrochloride is one of the most important drugs used to treat arrhythmias. The USP monograph for amiodarone hydrochloride describes an HPLC method for the quantification of seven impurities, however, this method shows problems that result in unresolved peaks. Moreover, there is no monograph for tablets in this compendium. Thus, a stability indicating HPLC method was developed for the determination of amiodarone, its known impurities and degradation products in tablets. A detailed forced degradation study was performed submitting amiodarone API, tablets and placebo to different stress conditions: acid and alkaline hydrolysis, oxidation, metal ions, heat, humidity, and light. Amiodarone hydrochloride API was susceptible to degradation in all stress conditions. The tablets also showed degradation in all environments, except in acidic condition. The analytes separation and quantification were achieved on an Agilent Zorbax Eclipse XDB-C18 column (100 x 3.0 mm, 3.5 µm). The mobile phase was composed of 50 mM acetate buffer pH 5.5 (A) and a mixture of methanol-acetonitrile (3:4, v/v) (B) in gradient elution. The method was validated in the range of 350-650 µg/mL for assay and 10-24 µg/mL for impurities determination. Therefore, this method can be used both for stability studies and routine quality control analyses.

Degradation studies of quetiapine fumarate by liquid chromatography-diode array detection and tandem mass spectrometry methods.

Quetiapine fumarate (QUE) is an antipsychotic agent with a chemical structure that is susceptible to degradation; therefore, it is important to study its stability using appropriate analytical tools. Knowledge of the stability profile of a drug is important because chemical degradation of its active component often results in a loss of potency, affecting its efficacy and safety. This current work reports degradation studies of QUE as drug substance, under different stress conditions such as oxidation, hydrolysis, heat, humidity and photolysis, by a stability-indicating LC method. The chemical stability was evaluated using a simple HPLC/diode array detection method, with a core-shell C18 column under isocratic conditions, which allows the separation of all primary degradation products (DPs) in a short run time. QUE was mainly degraded under oxidative and hydrolytic conditions, with the formation of three and two DPs, respectively, which were identified by electrospray ionization-tandem mass spectrometry. The method was properly validated in terms of linearity, accuracy, precision, selectivity, robustness and quantitation limit. Commercial tablets containing 25 mg of QUE were quantified, with results obtained within the United States Pharmacopeia limits. The proposed method is suitable to assess the stability and perform routine analysis of QUE in pharmaceutical samples.

Stability and degradation products of imipenem applying high-resolution mass spectrometry: An analytical study focused on solutions for infusion.

Carbapenems show recognized instability in aqueous solutions; therefore some care must be taken in their handling and preparation and their use in the hospital environment. The stability and degradation products of imipenem were investigated from conditions that simulate its clinical use. For this, a simple stability-indicating method by HPLC-DAD was validated with a focus on the quantitation of drug concentration remaining from infusion solutions (sodium chloride 0.9% and glucose 5%). The degradation products formed were identified by high-resolution mass spectrometry (ESI-Q-TOF-MS/MS), with detection of the [M + H]+ ions at m/z 318 (DP-1), m/z 599 (DP-2) and m/z 658 (DP-3). The most probable elemental compositions were obtained with a high degree of confidence, where the error between the masses observed and calculated was 1.25 ppm for DP-1, -0.33 ppm for DP-2 and 1.82 ppm for DP-3. The DP-1 degradation product resulted from cleavage of the ß-lactam ring; DP-2 corresponded to the drug dimer; and DP-3 was generated from the interaction between imipenem and cilastatin. The proposed method provides a safe and reliable alternative for the quantitation of imipenem, and the stability data obtained by ESI-Q-TOF help in understanding the drug behavior under the conditions of clinical use.

A novel, simplified and stability-indicating high-throughput ultra-fast liquid chromatography method for the determination of rosmarinic acid in nanoemulsions, porcine skin and nasal mucosa.

Currently, there is an increasing interest on the development of topical formulations containing rosmarinic acid (RA) due to its well-documented antioxidant activity. This study aimed to develop and validate a stability-indicating ultra-fast liquid chromatography (UFLC) method for the determination of RA in nanoemulsions, porcine skin and nasal mucosa intended to be applied in permeation/retention studies and for development of topical nanoemulsions. Chromatographic separation was carried out using a C18 column packed with 2.6 µm particle size in isocratic conditions using as mobile phase water:acetonitrile (83:17, v/v), acidified with 0.1% trifluoracetic acid (v/v), with a total time of analysis of 3.5 min and detection at 330 nm. RA analysis was specific in the presence of both non-biological (blank nanoemulsion and receptor fluid) and biological matrices (porcine ear skin and porcine nasal mucosa). No interference of degradation products of RA was verified after different stress conditions such as acidic, alkaline, oxidative, light exposure (UV-A and UV-C) and thermal demonstrating the method stability-indicating property. The analytical (0.1-10.0 µg·mL-1) and bioanalytical (0.5-10.0 µg·mL-1) linearity was proved by analysis of the calibration curves of RA and no matrix effect was observed. The method was sensitive, precise and accurate, and showed recovery higher than 85%. The method was considered robust as evaluated by a Plackett-Burman experimental design. In the validated conditions, the RA was determined in the nanoemulsions obtained by spontaneous emulsification procedure (1.007 ±â€¯0.040 mg·mL-1), porcine ear skin (1.13 ±â€¯0.19 µg·cm-2) and nasal mucosa (22.46 ±â€¯3.99 µg·cm-2) after retention/permeation studies. Thus, a highly sensitive, simple, fast and stability-indicating method was developed for RA analysis during the development of topical nanoemulsions and bioanalytical assays in complex matrices.

Forced degradation of gliquidone and development of validated stability-indicating HPLC and TLC methods

Forced degradation studies of gliquidone were conducted under different stress conditions. Three degradates were observed upon using HPLC and TLC and elucidated by LC-MS and IR. HPLC method was performed on C18 column using methanol-water (85:15 v/v) pH 3.5 as a mobile phase with isocratic mode at 1 mL.min-1 and detection at 225 nm. HPLC analysis was applied in range of 0.5-20 µg.mL-1 (r =1) with limit of detection (LOD) 0.177 µg.mL-1. TLC method was based on the separation of gliquidone from degradation products on silica gel TLC F254 plates using chloroform-cyclohexane-glacial acetic acid (6:3:1v/v) as a developing system with relative retardation 1.15±0.01. Densitometric measurements were achieved in range of 2 -20 µg /band at 254 nm (r = 0.9999) with LOD of 0.26 µg /band. Least squares regression analysis was applied to provide mathematical estimates of the degree of linearity. The analysis revealed a linear calibration for HPLC where a binomial relationship for TLC. Stability testing and methods validation have been evaluated according to International Conference on Harmonization guidelines. Moreover, the proposed methods were applied for the analysis of tablets and the results obtained were statistically compared with those of pharmacopeial method revealing no significant difference about accuracy and precision.

Development and validation of a stability-indicating LC-UV and LC-MS/MS methods for quantitative analysis of anisomycin and identification of degradation products

ABSTRACT Multifunctional drug anisomycin was subjected to forced degradation in accordance with International Conference on Harmonisation (ICH) guidelines for the first time. The drug was exposed to the recommended stress conditions of hydrolysis (acidic, alkaline and neutral), oxidation, thermal stress and photolysis, in order to investigate its stability. Optimized LC-MS/MS method was validated as recommended by ICH Q2(R1) guideline with respect to the specificity, accuracy, precision, limits of detection and quantitation, linearity and robustness. Anisomycin exhibited high instability under alkaline and thermal (neutral hydrolysis) conditions. It showed moderate stability under acidic, neutral, oxidative, thermal (acidic hydrolysis) and photolytic conditions, with the lowest degradation level observed in the case of light and oxidation stress. Formation of the same degradation product, identified as deacetylanisomycin, was observed under all applied stress conditions.

A comprehensive stability-indicating HPLC method for determination of chloroquine in active pharmaceutical ingredient and tablets: Identification of oxidation impurities.

Malaria is the most common parasitic disease in humans. It is estimated that 3 billion people live under the risk of contracting this disease in the world. Chloroquine (CQ) is the drug of choice to treat cases of non-complicated malaria. Forced degradation studies are important to know the drug's potentials degradation products and to develop a stability indicating method. Thus, chloroquine active pharmaceutical ingredient (API), chloroquine tablets and placebo were submitted to a detailed forced degradation study, using several stressing agents. The results were used on the development of a stability indicating method, using high performance liquid chromatography. The method was validated showing selectivity, precision, accuracy, robustness and linearity in the range of 30-360µg/mL of chloroquine. Chloroquine API and tablets were susceptible to alkaline hydrolysis with NaOH 1mol/L, and to oxidation with H2O2 3.0%. Two degradation products were formed in oxidative test. Kinetics of chloroquine degradation in alkaline hydrolysis was performed for both API and tablets. The calculated decay constant (k1) was 0.223days-1 for API and 0.182days-1 for tablets, while the half-life (t1/2) was 3.1days for API and 3.8days for tablets. Chemical structures have been proposed for the two degradation products formed in the presence of H2O2, using an UHPLC-UV-MS/MS approach.