Stability-indicating Chromatographic Method Research Articles

Development of electrochemical and stability-indicating chromatographic methods for the determination of cefprozil

Development of electrochemical and stability-indicating chromatographic methods for the determination of cefprozil

Green analytical chemistry-driven response surface modeling to stability-indicating chromatographic method for estimation of cilnidipine and application of high-performance thin-layer chromatography-mass spectrometry for characterization of degradation products.

Cilnidipine is a calcium channel blocker that is used to treat cardiac diseases such as angina and high blood pressure. Several column and planar chromatographic methods for estimating cilnidipine in pharmaceutical dosage forms have been documented. However, these methoddevelopments have been carried out employing organic solvents such as acetonitrile, methanol, toluene, chloroform, and others as mobile phase components or as sample pretreatment diluents. These organic solvents are neurotoxic and teratogenic to humans and aquatic animals, according to International Council for Harmonization Q3C (R8) recommendations. According to the green analytical chemistry approach, such organic solvents should be reduced or removed during the development of chromatographic methods for environmental protection and the safety of human and aquatic animal life. As a result, the stability-indicating chromatographic estimation of cilnidipine was performed utilizing less toxic organic solvents. To prevent organic solvent waste during method development, mobile-phase optimization was performed using the design of experiment-based response surface modeling. Cilnidipine has been subjected to hydrolysis, oxidation, photolysis, and dry-heat decomposition to determine its stability. The greenness profiles of the suggested and published chromatographic methods were examined using the national environment method index, analytical greenness calculator, green analytical procedure index software, and eco-scale assessment tool.

Principles of White Analytical Chemistry and Design of Experiments to Stability-Indicating Chromatographic Method for Simultaneous Estimation of Thiocolchicoside and Lornoxicam.

A variety of chromatographic methods have been published for the stability evaluation of thiocolchicoside and lornoxicam. Nevertheless, the development of chromatographic methods requires the use of neurotoxic and teratogenic organic solvents that are detrimental to the environment and harmful to human life. Using the principles of design of experiments (DoE), a novel white analytical chemistry-driven stability-indicating high-performance thin layer chromatographic (SI-HPTLC) method has been developed for the concurrent stability study of thiocolchicoside (THC) and lornoxicam (LNX). To protect the environment and human life, the stability-indicating HPTLC method was developed using safe organic solvents. Potential analytical method risk parameters (AMRPs) and analytical method performance attributes (AMPAs) were screened using the fractional factorial design. The response surface analysis and optimization of critical AMRPs and AMPAs was carried out using full factorial design. Navigation of the method operable design region (MODR) was used to develop the SI-HPTLC technique. The developed method was validated as per ICH (International council for harmonization) Q2(R1) guideline. The developed method's greenness was evaluated using AGREE (Analytical Procedure Greenness) tool and ESA (Eco-Scale Assessment). The Blue (B) model was used to assess the proposed method's cost and time efficiency and user-friendlyness. For the stability studies of THC and LNX, the twelve principles of WAC (White Analytical Chemistry) were used to evaluate the published and proposed chromatographic techniques. As compared to previously published chromatographic techniques for studying the stability of THC and LNX, the suggested approach was found to be more affordable, environmentally friendly, and user-friendly. Development of stability-indicating HPTLC method using a novel white analytical chemistry approach and organic solvents with low toxicity potential. Application of the developed method for analysis of the forced degraded sample and fixed-dose combinations of THC and LNX.

Red, Green and Blue Model-based Assessment and Principles of White Analytical Chemistry to Robust Stability-Indicating Chromatographic Estimation of Thiocolchicoside and Diclofenac Sodium.

White analytical chemistry (WAC) is a recent approach for evaluating analytical procedures based on their effectiveness in validating results, capacity to be environmentally friendly and economic effectiveness. The detection of diclofenac sodium (DCF) and thiocolchicoside (THC) simultaneously has been established using a WAC-driven stability indicating chromatographic method (SICM). For the concurrent stability study of THC and DCF, the suggested chromatographic technique was developed employing a safe and environmentally acceptable organic solvents. To identify critical analytical method parameters (AMPs) and analytical quality attributes (AQAs), the design of experiments (DoE)-based screening design was applied. For the DoE-based response surface modelling (RSM) of critical AMPs and AQAs, the Box-Behnken design (BBD) was employed. A robust SICM was developed by navigating the analytical design space for simultaneous estimation of THC and DCF. The IR, NMR, and mass spectral data were used to characterize the degradation products. The red, green, and blue (RGB) models were used to evaluate the suggested method's validation effectiveness, greenness power, and economic efficiency with published chromatographic techniques. The effectiveness of the chromatographic method's validation concerning the ICH Q2 (R1) guideline was evaluated using the red model. Analytical greenness (AGREE) evaluation tool and eco-scale assessment (ESA) approach were used to evaluate the green model's methodology. The blue model-based assessment was carried out for comparison of handling of instruments, cost, and time during sample analysis. The red, blue, and green scores of the techniques were averaged to arrive at the white score of the suggested and reported methods. For the concurrent stability study of THC and DCF, the suggested technique was shown to be validated, environmentally friendly, and cost-effective. The suggested approach could be a cost-effective and environmentally friendly analytical technique for determining the stability and monitoring the quality of fixed-dose combinations of THC and DCF. Development of stability-indicating HPTLC method for concomitant analysis of THC and DCF using concepts of DoE and white analytical chemistry.

Pharmaceutical Oral Formulation of Methionine as a Pediatric Treatment in Inherited Metabolic Disease.

L-Methionine (Met) is an essential alpha-amino acid playing a key role in several metabolic pathways. Rare inherited metabolic diseases such as mutations affecting the MARS1 gene encoding methionine tRNA synthetase (MetRS) can cause severe lung and liver disease before the age of two years. Oral Met therapy has been shown to restore MetRS activity and improve clinical health in children. As a sulfur-containing compound, Met has a strongly unpleasant odor and taste. The objective of this study was to develop an optimized pediatric pharmaceutical formulation of Met powder, to be reconstituted with water, to obtain a stable oral suspension. Organoleptic characteristics and physicochemical stability of the powdered Met formulation and suspension were evaluated at three storage temperatures. Met quantification was assessed by a stability-indicating chromatographic method as well as microbial stability. The use of a specific fruit flavor (e.g., strawberry) with sweeteners (e.g., sucralose) was considered acceptable. No drug loss, pH changes, microbiological growth, or visual changes were observed at 23 ± 2 °C and 4 ± 2 °C with the powder formulation for 92 days, and the reconstituted suspension for at least 45 days. The developed formulation facilitates the preparation, administration, the dose adjustment and palatability of Met treatment in children.

Quality risk assessment and DoE – Practiced validated stability-indicating chromatographic method for quantification of Rivaroxaban in bulk and tablet dosage form

AbstractA systematic DoE and Analytical Quality by Design (AQbD) approach was utilized for the development and validation of a novel stability indicating high-performance thin–layer chromatographic (HPTLC) method for Rivaroxaban (RBN) estimation in bulk and marketed formulation. A D-optimal design was used to screen the effect of solvents, volume of solvents, time from spotting to development and time for development to scanning. ANOVA results and Pareto chart revealed that toluene, methanol, water and saturation time had an impact on retention time. The critical method and material attributes were further screened by Box-Behnken design (BBD) to achieve optimal chromatographic condition. A stress degradation study was carried out and structure of major alkaline degradant was elaborated. According to the design space, a control strategy was used with toluene: methanol: water (6:2:2) and the saturation time was 15 min. A retention factor (RF) of 0.59 ± 0.05 was achieved for RBN using chromatographic plate precoated with silica gel at detection wavelength 282 nm with optimized conditions. The linear calibration curve was achieved in the concentration range of 200–1,200 ng/band with r2 > 0.998 suggesting good coordination between analyte concentration and peak areas. The quadratic model was demonstrated as the best fit model and no interaction was noted between CMAs. The optimized HPTLC method was validated critically as stated in International Conference on Harmonization (ICH) Q2 (R1) guideline and implemented successfully for stress degradation study of RBN. The developed HPTLC method obtained through AQbD application was potentially able to resolve all degradants of RBN achieved through forced degradation study. The obtained results demonstrate that a scientific AQbD approach implementation in HPTLC method development and stress degradation study drastically minimizes the number of trials in experiments, ultimately time and cost of analysis could be minimized.

Two Stability Indicating Chromatographic Methods: TLC Densitometric versus HPLC Method for the Simultaneous Determination of Brinzolamide and Timolol Maleate in Ophthalmic Formulation in the Presence of Probable Carcinogenic Oxidative Degradation Product of Timolol Maleate

A comparative study between two stability-indicating chromatographic methods for the assay of brinzolamide and timolol maleate in the co-existence of the probable carcinogenic oxidative degradation product of timolol maleate in their ophthalmic formulation was demonstrated. The first method established the thin-layer chromatography coupled with the densitometric determination of the analyzed spots, using silica gel TLC aluminum plates F254 and a developing system of chloroform: methanol: ammonia (6:1:0.1, in volumes) at room temperature to give good separation for the three investigated components, where retardation factors for the oxidative degradation product of timolol maleate, brinzolamide and timolol maleate were (Rf 0.21), (Rf 0.46), and (Rf 0.55), respectively. The linear ranges were 2–10 and 3–16 μg/band for brinzolamide and timolol maleate, respectively. In the second method, high performance liquid chromatography (HPLC), photo diode array detection was used on a Eurospher 5 µm C18 100 Å (4.6 × 250 mm) column, using triethylamine pH 3.5, adjusted by glacial acetic acid: acetonitrile (20:80, v/v) at a rate of 0.5 mL per minute. An acceptable separation was achieved, where the retention times for timolol maleate, the oxidative degradation product of timolol maleate and brinzolamide, were (Rt 3.6), (Rt 4.7), and (Rt 5.6), respectively. Linearity covered a range of 20–120 μg/mL for both drugs. It has been proved previously that timolol maleate is liable to oxidation, giving a high-probability carcinogenic product in female mice. The validation for the new proposed stability-indicating methods was optimized in line with the ICH guidelines with good outcomes. It is worth noting that the HPLC-DAD method showed superior separation, economic and time-saving results, while TLC method was more sensitive.

Tailoring two white chromatographic platforms for simultaneous estimation of ritonavir-boosted nirmatrelvir in their novel pills: degradation, validation, and environmental impact studies.

As the COVID-19 pandemic is not yet over, Pfizer has launched the novel pill Paxlovid® (Nirmatrelvir (NMV) co-packaged with ritonavir (RIT)) as an effective medication for hospitalized and non-hospitalized patients. Making pharmaceutical analysis greener and more sustainable has lately become the main direction of the research community. In this context, two fast, green, and stability-indicating chromatographic methods were designed for the neat quantitative determination of NMV and RIT in their bulk and dosage forms. Method I is deemed the first electro-driven attempt for the assay of Paxlovid®. Herein, the optimized conditions of the Micellar Electrokinetic Chromatographic (MEKC) method were 50 mM borate buffer at pH 9.2 with 25 mM sodium lauryl sulfate (SDS) being used as the background electrolyte (BGE) on a deactivated fused silica capillary (50 cm effective length × 50 μm id). Method II was an isocratic reversed-phase HPLC separation method using Zorbax-Eclipse C18 (4.6 × 250 mm, 5 μm particle size) column and 50 mM ammonium acetate buffer at pH 5 and acetonitrile as mobile phase constituents at a flow rate of 1 mL min-1. For the sake of simplicity and increasing sensitivity, a single wavelength of 210 nm was used for the two methods to assay both drugs. Linear correlations between peak areas and concentration were observed in the ranges of 10-200 μg mL-1 for NMV and 5-100 μg mL-1 RIT in both methods. The impact of versatile stress conditions such as hydrolysis, oxidation, and photolysis on the stability of NMV and RIT was studied. Fortunately, both methodologies were able to separate both drugs from their degradants. Thus, the stability indicating power of the methods was proved. The derived methods were statistically validated in agreement with the ICH guidelines. Furthermore, the environmental friendliness and sustainability of these methods were investigated and compared with the cited methods using the holistic multicriteria evaluation tools namely Hexagon, AGREE, and RGB12 metrics. Conclusively, the proposed methods offered reliable, feasible, economic, white, and stability-indicating alternatives to the cited chromatographic methods.

Stability-indicating RP-HPLC method development and validation for simultaneous estimation of telmisartan and rosuvastatin calcium in bulk and in tablet dosage form

BackgroundThe stability-indicating chromatographic method was developed and validated for simultaneous estimation of telmisartan and rosuvastatin calcium in bulk and in tablet dosage form. The RP-HPLC elution was carried out at 242.0 nm using column Oyster ODS3 (150 × 4.6 mm, 5 µm) isocratically, and a mobile phase containing 10 mM phosphate buffer with 1.1 g octane-1-sulfonic acid sodium salt having pH 2.5 (adjusted with 5% OPA) and acetonitrile, with a proportion of 500:500, v/v was pumped through the column maintained at ambient (about 25 °C) temperature with 1.0 mL/min flow rate. The proposed method was validated according to ICH Q2 (R1) guideline.ResultsTelmisartan and rosuvastatin were eluted at 2.553 min and 4.505 min, respectively. The method is linear from 99.9073 to 299.7218 µg/mL for telmisartan (R2 = 1.000) and 23.6841 – 71.0522 µg/mL for rosuvastatin (R2 = 0.999). The average recovery percentage was found 100.51, 99.76, and 99.14% for telmisartan and 99.68, 99.72, and 98.56% for rosuvastatin at three different levels. Results of method repeatability and intermediate precision were found within acceptable limits. Results of solution stability showed that mobile phase was stable for 2 days; standard and sample preparations are stable for 1 day at room temperature as well as in the refrigerator (2–8 °C). Also, forced degradation study results show that method is stability indicating as capable of distinguishing the active analytes peak from the degraded product.ConclusionThe developed stability-indicating method is linear in studied concentration range as well as precise, accurate, specific, and robust. Hence, successfully this method can be used for routine analysis and stability study.Graphical abstract

Greenness Assessment of Two Validated Stability-Indicating Chromatographic Methods for Estimating Modafinil Using the Analytical Eco-Scale.

Modafinil (MDF) is one of the drugs used for the treatment of narcolepsy. This manuscript describes the development and validation of two chromatographic stability-indicating methods for MDF in the presence of its acid-induced degradation product. MDF was degraded under different stress conditions and identification of the degradation product was performed using IR and mass spectroscopy. The first method involved TLC, in which plates precoated with silica gel G60 F254 were used and the developing system was dichloromethane- methanol (9:1, v/v). The second method was an eco-friendly (HPLC) method that utilized a C-18 column and ethanol-H2O (30:70, v/v) as a mobile phase with a flow rate of 1 mL/min and UV detection at 220 nm. Good linear relationships were obtained within the ranges 1-10 µg/band and 2-10 µg/mL for TLC-densitometry and HPLC, respectively. The obtained results were statistically compared with those of the official HPLC method and showed no significant difference with respect to their accuracy and precision at P = 0.05. Greenness scores represent excellent green analysis results in comparison with the reported studies. The proposed methods were validated according to ICH guidelines and were applied on bulk powder and pharmaceutical dosage forms using eco-friendly mobile phases in line with worldwide trends. Chromatographic methods have been validated for the estimation of MDF in the presence of its degradation product. Clarification of the degradation pathway and elucidation of the structure were stated for the first time. This is the first published method using greenness assessment metrics for the analysis of MDF.

Full Factorial Design for Development and Validation of a Stability-Indicating RP-HPLC Method for the Estimation of Timolol Maleate in Surfactant-Based Elastic Nano-Vesicular Systems.

A novel isocratic stability-indicating chromatographic method was developed, optimized and validated using Design-Expert® following ICH guidelines for the quantification of Timolol maleate (TM). The intrinsic stability of TM was assessed by force degradation studies, which concluded no extensive degradation except under alkaline and oxidative conditions. TM was quantified accurately in the surfactant-based elastic vesicular system by separating it on Hypersil BDS C8 column using triethylamine in H2O (0.15%v/v; pH3.0) and acetonitrile (ACN; 65:35%v/v). The influence of variable factors like mobile phase pH, injection volume (μL), flow rate (mL/min) and ACN content (%) on method responses were assessed using a full factorial design. The method was linear between 0.05 and 10μg/mL with an R2 value of 0.9993. Limit of detection and limit of quantification were found to be 0.90 and 27.2ng/mL. The method was specific, with recovery in plain drug solution of 89-92% and elastic nanovesicles of 90-93%. The experimental model was significant (P < 0.0001) as indicated by deliberate changes in the method analyzed through analysis of variance. The total drug content in elastic nanovesicles was estimated to be 9.53 ± 0.01mg/20-mL dispersion and entrapment efficiency was 44.52 ± 0.73%. The developed method was rapid, economic and precise for the quantification of TM in bulk and vesicular system.

Stability-Indicating Chromatographic Methods for the Simultaneous Determination of Probenecid and Colchicine in Their Combined Tablet.

Two stability-indicating chromatographic methods have been established and validated for concurrent determination of probenecid (PRO), colchicine (COL) along with the degradation product of colchicine (COL deg). PRO and COL were exposed to a stress stability study, which includes acidic, alkaline, oxidative, photolytic and thermal degradations. Chromatographic methods included the use of thin layer chromatography (TLC-densitometry) and high performance liquid chromatography (HPLC). In the first method, separation was achieved by using aluminum TLC plates that were precoated with silica gel G.F254 as the stationary phase and ethyl acetate-methanol-33%ammonia (8:1:1, by volume) as a mobile phase. The obtained chromatograms were scanned at 254nm. The second method was based on HPLC using a RP- C18 column with isocratic elution. Good separation was obtained through a mobile phase comprised of phosphate buffer pH5-acetonitrile (70:30, v/v) at a flow rate of 1.0mLmin-1 and ultraviolet detection at 254nm. Different parameters affecting efficiency of the two methods were studied accurately for optimum separation of the three cited components. The suggested methods were validated according to the International Conference on Harmonization (ICH) guidelines and were applied for bulk powder and commercial tablets.

Quality and Stability Profile Assessment of the Recent Antidiabetic Omarigliptin by Using Different Chromatographic Methods.

In a contribution to stability profiling of the recent antidiabetic drug, omarigliptin (OMR), two stability-indicating chromatographic methods were developed and validated. Stability profiling was performed for OMR under different stress conditions as acidic, alkaline, oxidative, photolytic and thermal degradations. Structures elucidation to all formed degradation products were identified using IR and mass spectrometry. Thin Layer Chromatography (TLC) and High-Performance Liquid Chromatography (HPLC) were used. In TLC-densitometric method, aluminum TLC plates precoated with silica gel G.F254 were used as stationary phase along with methanol: ethyl acetate: 33% ammonia (2:8:1,v/v/v) as mobile phase. The obtained chromatograms were scanned at 254nm over concertation range of 5-70μg band-1 for OMR. The second chromatographic method was an HPLC one with diode array detection and RP-C18 column with isocratic elution. Mobile phase used was composed of phosphate buffer pH3.5: acetonitrile (80, 20, v/v), delivered at flow rate of 1.0mLmin-1. Diode array detector was adjusted at 230nm with linearity range of 15-180μgmL-1 for OMR. Several factors affecting TLC and HPLC efficiency have been carefully studied. The developed methods were validated according to International Conference on Harmonization guidelines and successfully applied for assessment of OMR in bulk powder and tablets.

Formulation and Stability of Ataluren Eye Drop Oily Solution for Aniridia

Congenital aniridia is a rare and severe panocular disease characterized by a complete or partial iris defect clinically detectable at birth. The most common form of aniridia occurring in around 90% of cases is caused by PAX6 haploinsufficiency. The phenotype includes ptosis, nystagmus, corneal limbal insufficiency, glaucoma, cataract, optic nerve, and foveal hypoplasia. Ataluren eye drops aim to restore ocular surface PAX6 haploinsufficiency in aniridia-related keratopathy (ARK). However, there are currently no available forms of the ophthalmic solution. The objective of this study was to assess the physicochemical and microbiological stability of ataluren 1% eye drop in preservative-free low-density polyethylene (LDPE) bottle with an innovative insert that maintains sterility after opening. Because ataluren is a strongly lipophilic compound, the formulation is complex and involves a strategy based on co-solvents in an aqueous phase or an oily formulation capable of totally dissolving the active ingredient. The visual aspect, ataluren quantification by a stability-indicating chromatographic method, and microbiological sterility were analyzed. The oily formulation in castor oil and DMSO (10%) better protects ataluren hydrolysis and oxidative degradation and permits its complete solubilization. Throughout the 60 days period, the oily solution in the LDPE bottle remained clear without any precipitation or color modification, and no drug loss and no microbial development were detected. The demonstrated physical and microbiological stability of ataluren 1% eye drop formulation at 22–25 °C might facilitate clinical research in aniridia.

Stability assessment of tamsulosin and tadalafil co-formulated in capsules by two validated chromatographic methods.

The advent of a new pharmaceutical formulation evokes the need for examining the chemical stability of their constituents and establishing proper stability-indicating methods. Herein, the stability of the newly co-formulated Tamsulosin and Tadalafil were examined under different stress conditions. The acidic degradation of Tamsulosin yielded its sulfonated derivative, while Tadalafil was susceptible to both acidic and basic degradation. Two stability-indicating chromatographic methods, namely; high-performance thin-layer chromatography and high-performance liquid chromatography, have been developed. Significant high-performance thin-layer chromatography-fractionation could be achieved by utilizing a stationary phase of silica gel 60 F254 and a mobile phase composed of ethyl acetate/toluene/methanol/ammonia (4:2:4:0.6, by volumes) with densitometric recording at 280nm over a concentration range of 0.5-25μg/band for both drugs. The HPLC-separation could be reached on XBridge® C18 column isocraticaly by using a mobile phase having acetonitrile/phosphate buffer, pH 6.0 (45:55, v/v) pumped at a flow rate of 1.7mL/min and applying diode array ultraviolet-detection at 210nm over a linearity range of 3-70μg/mL for each drug. Specificity of the two methods was additionally assured via peak purity assessment. Moreover, the methods were distinctly exploited for evaluating the drugs' stability in accelerated stability-studied samples of Tamplus® capsules.

Validated Stability Indicating Chromatographic Methods for Quantification of Imidocarb Dipropionate; Application for the Determination of Its Residues in Bovine Meat and Milk Samples.

Imidocarb dipropionate (IMD) is an immunomodulator agent commonly used for treatment of anaplasmosis in cattle. Thus, two sensitive, specific, and precise stability-indicating chromatographic methods have been developed, optimized, and validated for its determination in presence of its acid, alkaline, and oxidative stressed degradation products. The first method is based on separation of IMD and its forced induced degradation products on reversed phase cyano column using isocratic elution system consisted of sodium acetate buffer-methanol-acetonitrile (55: 30:15, v/v/v), pH 4.6 at a flow rate of 1.2 mL/min, and UV detection at 254 nm. The second method utilized TLC combined with densitometric determination of the separated bands at 254 nm. The separation was achieved using silica gel 60 F254 TLC plates with a mixture of ethyl acetate-methanol-ammonia-water (8.5:1:0.5:0.2, v/v/v/v) as a developing system. HPLC analysis was applied in range of 0.25-40 µg/mL with LOD of 0.073 µg/mL. While densitometric measurements showed linearity in the range of 0.1-1.8 µg/band with LOD of 0.02 µg/band. The suggested methods were validated in compliance with the ICH guidelines and were successfully applied for determination of IMD in its commercial veterinary formulations with good recoveries. Furthermore, the proposed HPLC method was extended to the determination of IMD residues in bovine meat and milk samples. Bovine meat, HPLC, Imidocarb dipropionate, Milk, TLC.

Development and Validation of Stability Indicating Chromatographic Methods for Determination of Azilsartan Medoxomil in Pharmaceutical Formation

Two stability-indicating chromatographic methods namely, reverse-phase high-performance liquid chromatography (RP-HPLC) and high-performance thin-layer chromatography (HPTLC) were developed and validated for the determination of azilsartan medoxomil from pharmaceutical dosage form in presence of its degradation products as per ICH guideline. In RP-HPLC, separation was performed with Hiber® C-18 column (250 mm X 4.6 mm, 5 μm), using mobile phase methanol: acetonitrile: water (88:8:4 v/v/v) at a flow rate of 0.5 ml/min. The analyte was detected at 254 nm over a concentration range of 20 - 70 μg/ml with correlation coefficient of 0.999. In HPTLC, separation was carried out with silica gel G60 F254 aluminum sheet using acetone: toluene: ammonia (8.2:1.7:0.1 v/v/v) as a developing system. Linearity of the proposed HPTLC method was found 500 - 900 ng/band and correlation coefficient 0.9970 at 254 nm. Besides, stress degradation study was also carried out wherein degraded product peaks were well resolved from the analyte peak with difference in their retention time and retardation factor in RP-HPLC and HPTLC methods respectively. Statistical analysis proved that there were no significant differences between the two validated methods. The proposed stability-indicating methods can be applied for the analysis of azilsartan medoxomil in pharmaceutical formulations for quality control.

Stability-indicating chromatographic and UV spectrophotometric methods for determination of colchicine

Colchicine is an alkaloid that used in the relief of acute gout. Three simple, sensitive, selective and rapid methods have been developed for the determination of colchicine in the presence of its alkaline degradation product with good applicability on its pharmaceutical formulation. The first method was based on TLC separation of colchicine and its degradation using chloroform/methanol/conc ammonia (8:2:0.1 v/v/v) as a mobile phase and densitometric detection at 350 nm. The second method was HPLC using kromasil C18 column and a mobile phase of methanol/ammonia (100:1.5 v/v) with UV detection at 246 nm. The third method was spectrophotometry which involved induced dual wavelength method at 245 nm and 261 nm and first derivative of ratio spectra at 302.4 nm. The developed methods were validated according to ICH guidelines and successfully applied for the determination of colchicine in tablets.

Chromatographic Separation of the Novel Hypoglycemic Drug Mitiglinide in its Bulk Powder and Pharmaceutical Formulation: Forced Degradation and Validated Stability-Indicating HPTLC/Densitometry and HPLC/UV Methods.

Mitiglinide (MTG) is one of meglitinides group which are used for treatment of type two diabetes mellitus. Mitiglinide (MTG) is a novel oral hypoglycemic drug. The present work adopts two stability-indicating chromatographic methods for determination of MTG after being exposed to forced degradation using 4 M methanolic HCl for 12 h. The first method is HPTLC/densitometry using methanol:chloroform:acetic acid (5:2.5:0.3 by volume) as the eluting system and silica gel 60 GF254 as the stationary phase; the separated bands were then scanned at 220 nm. The second method is HPLC/UV in which acetonitrile:methanol:0.05 M potassium dihydrogen orthophosphate (pH 3.5) (40:25:35 by volume) was used as the mobile phase and a Zorbax SB-C8 (250 × 4.6 mm, 5 µm) column as a stationary phase, at a flow rate of 1 mL/min and UV detection at 220 nm. As a result of acid hydrolysis, two degradants were obtained. The first one was benzyl succinic acid to which this study was performed. The second one lacked configuration and was unreadable using UV spectrometry. Linearity was in the range of 8-48 µg/band MTG for HPTLC and 10-80 µg MTG for HPLC. LOD and LOQ values were 1.85 and 5.62 µg/band for the HPTLC method and 2.14 and 6.49 µg/mL for the HPLC method, respectively. The Recovery % was 100.03 ± 1.464 and 99.61 ± 1.44 using the HPTLC and HPLC methods, respectively. The relative standard deviations (RSD, %) for intra- and inter-day assays were 1.111 and 1.430 for the HPTLC method, respectively, and those for the HPLC method were 1.377 and 0.866, respectively. The RSD, %, for robustness testing was 1.162 (saturation time of mobile phase) and 1.592 (change in ratio of methanol content) for the HPTLC method and 1.377 (mobile phase composition), 1.713 (detector wavelength) and 1.770 (mobile phase flow rate) for the HPLC method. The adopted methods were successfully applied for the determination of MTG in its pure form, in presence of its acid degradant and in its tablet dosage form. Statistical comparison between the results obtained from the developed methods and those obtained by the reported HPLC method showed no significance difference.

Development and optimization of a stability-indicating chromatographic method for verapamil hydrochloride and its impurities in tablets using an analytical quality by design (AQbD) approach

Development and optimization of analytical methods for quantifying verapamil hydrochloride in its twelve impurities is a challenge for analytical chemists and pharmacists. The aim of this paper was to apply the analytical quality by design (AQbD) and design of experiments (DoE) approaches in the development of a robust, low-cost, regulatory-flexible, fit for purpose high-performance liquid chromatography (HPLC) analytical method to determine VPM and its impurities. A Placket-Burman screening design was adopted to identify the most relevant analytical conditions affecting the chromatographic responses. In addition, a central composite optimization design was used to establish regression models explaining the chromatographic responses as functions of the buffer pH, concentration of ammonium hydroxide in mobile phase, and the injection volume of test solutions. Response surface methodology allowed for establishing the method operable design space, which ensures suitable method performance with respect to all chromatographic responses studied. Optimal chromatographic conditions were achieved using a gradient elution consisting of a mixture of 10 mM ammonium formate buffer pH and acetonitrile, with a flow rate of 0.7 mL/min, and a XSelect CSH C18 100 mm x 4.6 mm 3.5 µm chromatographic column. The optimized analytical method was selective, linear (320–480 µg/mL for VPM and 0.4–4.8 µg/mL for impurities), precise (0.5% and 1.0% for VPM and impurities, respectively), accurate (mean recovery of 101.0% and 102.5% for VPM and impurities, respectively), and robust. In addition, the application of the validated analytical method in forced degradation conditions allowed for studying the degradation profile of verapamil hydrochloride, particularly in acid and oxidative degradation conditions.