Implementation of QbD Approach to the Analytical Method Development and Validation for the Estimation of Metformin Hydrochloride in Tablet Dosage Forms by HPLC

Quality by Design for Preclinical In Vitro Assay Development

Quality by Design (QbD) is an approach to assay development to determine the design space, which is the range of assay variable settings that should result in satisfactory assay quality. Typically, QbD is applied in manufacturing, but it works just as well in the preclinical space. Through three examples, we illustrate the QbD approach with experimental design and associated data analysis to determine the design space for preclinical assays.

Experimental and Theoretical Design on the Development of Matrix Tablets with Multiple Drug Loadings Aimed at Optimizing Antidiabetic Medication

Background: Diabetes is a growing global health crisis that requires effective therapeutic strategies to optimize treatment outcomes. This study aims to address this challenge by developing and characterizing extended-release polymeric matrix tablets containing metformin hydrochloride (M-HCl), a first-line treatment for type 2 diabetes, and honokiol (HNK), a bioactive compound with potential therapeutic benefits. The objective is to enhance glycemic control and overall therapeutic outcomes through an innovative dual-drug delivery system. Methods: The tablets were formulated using hydrophilic polymers, such as Carbopol® 71G NF and Noveon® AA-1. The release kinetics of M-HCl and HNK were investigated through advanced mathematical models, including fractal and multifractal dynamics, to capture the non-linear and time-dependent release processes. Traditional kinetic models (zero-order, first-order, Higuchi equations) were also evaluated for comparison. In vitro dissolution studies were conducted to determine the release profiles of the active ingredients under varying polymer concentrations. Results: The study revealed distinct release profiles for the two active ingredients. M-HCl exhibited a rapid release phase, with 80% of the drug released within 4-7 h depending on polymer concentration. In contrast, HNK demonstrated a slower release profile, achieving 80% release after 9-10 h, indicating a greater sensitivity to polymer concentration. At shorter intervals, drug release followed classical kinetic models, while multifractal dynamics dominated at longer intervals. Higher polymer concentrations resulted in slower drug release rates due to the formation of a gel-like structure upon hydration, which hindered drug diffusion. The mechanical properties and stability of the matrix tablets confirmed their suitability for extended-release applications. Mathematical modeling validated the experimental findings and provided insights into the structural and time-dependent factors influencing drug release. Conclusions: This study successfully developed dual-drug extended-release matrix tablets containing metformin hydrochloride and honokiol, highlighting the potential of hydrophilic polymers to regulate drug release. The findings emphasize the utility of advanced mathematical models for predicting release kinetics and underscore the potential of these formulations to improve patient compliance and therapeutic outcomes in diabetes management.

Multifractal Analysis and Experimental Evaluation of MCM-48 Mesoporous Silica as a Drug Delivery System for Metformin Hydrochloride

Background: This study explored the potential of MCM-48 mesoporous silica matrices as a drug delivery system for metformin hydrochloride, aimed at improving the therapeutic management of type 2 diabetes mellitus. The objectives included the synthesis and characterization of MCM-48, assessment of its drug loading capacity, analysis of drug release profiles under simulated physiological conditions, and the development of a multifractal dynamics-based theoretical framework to model and interpret the release kinetics. Methods: MCM-48 was synthesized using a sol-gel method and characterized by SEM-EDX, TEM, and nitrogen adsorption techniques. Drug loading was performed via adsorption at pH 12 using metformin hydrochloride solutions of 1 mg/mL (P-1) and 3 mg/mL (P-2). In vitro dissolution studies were conducted to evaluate the release profiles in simulated gastric and intestinal fluids. A multifractal dynamics model was developed to interpret the release kinetics. Results: SEM-EDX confirmed the uniform distribution of silicon and oxygen, while TEM images revealed a highly ordered cubic mesoporous structure. Nitrogen adsorption analyses showed a high specific surface area of 1325.96 m²/g for unloaded MCM-48, which decreased with drug loading, confirming efficient incorporation of metformin hydrochloride. The loading capacities were 59.788 mg/g (P-1) and 160.978 mg/g (P-2), with efficiencies of 99.65% and 89.43%, respectively. In vitro dissolution studies showed a biphasic release profile: an initial rapid release in gastric conditions followed by sustained release in intestinal fluids, achieving cumulative releases of 92.63% (P-1) and 82.64% (P-2) after 14 hours. The multifractal dynamics-based theoretical release curves closely matched the experimental data. Conclusions: MCM-48 mesoporous silica effectively enhanced metformin delivery, offering a controlled release profile well-suited for type 2 diabetes management. The multifractal theoretical framework provided valuable insights into drug release dynamics, contributing to the advancement of innovative drug delivery systems.

Analytical quality by design approach for the development of high-performance liquid chromatography method for simultaneous analysis of metformin and sitagliptin in the presence of major degradation products

An analytical quality by design-based high-performance liquid chromatography method for determining metformin (MET) and sitagliptin (SIT) in stress-degraded samples was developed and validated. The analytical target profile and risk assessment-driven critical method variables, for example, pH, % aqueous, and buffer concentration, were studied for their effect on method responses of retention time and resolution using a central composite design. The correlation regression coefficient was more than 0.8, and variables interaction was significant on method responses with curvature effect. The method operable design region afforded an aqueous range of 55%-70% and an ortho-phosphoric acid buffer of 0.1% with a pH of 3.0-4.0 as a robust region for the suitable method performance characteristics. The separation of MET and SIT from their degradants (m/z 85.0509; m/z 193.0694) on the C8 column was achieved using a mobile phase consisting of 0.1% ortho-phosphoric acid and methanol (60:40% v/v; pH 3.0). The optimized method eluted MET and SIT at 4.3 ± 0.2 and 7.1 ± 0.2 min, respectively, with acceptable specificity and resolution. The linearity ranges of 25-250 μg/mL (r2 : 0.9982) and 5-50 μg/mL (r2 : 0.9989) was established for MET and SIT, respectively. The % recovery (98.81%-102.17%), precision (0.55%-1.65%), and robustness study for method variables were acceptable.

A brief review on application of design of experiment for the analysis of pharmaceuticals using HPLC

The quality pioneer Dr. Joseph M. Juran first proposed the idea of quality by design. According to him, pharmaceutical quality by design is an organised approach to product development that starts with predetermined goals and places an emphasis on product, process understanding, control based on reliable science and quality risk management. The quality of a product or process can typically be affected by a number of input elements. Design of experiments has been employed widely recently to understand the impacts of multidimensional and interactions of input parameters on the output responses of analytical procedures and pharmaceutical goods. Depending on the design of experiments objectives, screening, characterization, or optimization of the process and formulation, a variety of designs, such as factorial or mixture, can be used. The most popular designs used in the stage of screening or factor selection are the 2-Level Factorial and Plackett-Burman designs, both of which have two levels for each factor (k), both economical and effective, and in optimization widely used designs in this step are full factorial at three levels, central composite, Box-Behnken design. The analysis of variance, regression significance, and lack of fit of the regression model were some of the key topics covered in the discussion of the main components of multiple regression model adjustment. Design of experiments is thus the primary element of the formulation and analytical quality by design. The details about design of experiments used for the analysis of pharmaceutical formulation using HPLC.

The Applicability of Chromatographic Retention Modeling on Chiral Stationary Phases in Reverse-Phase Mode: A Case Study for Ezetimibe and Its Impurities

Mechanistic modeling is useful for predicting and modulating selectivity even in early chromatographic method development. This approach is also in accordance with current analytical quality using design principles and is highly welcomed by the authorities. The aim of this study was to investigate the separation behavior of two different types of chiral stationary phases (CSPs) for the separation of ezetimibe and its related substances using the mechanistic retention modeling approach offered by the Drylab software (version 4.5) package. Based on the obtained results, both CSPs presented with chemoselectivity towards the impurities of ezetimibe. The cyclodextrin-based CSP displayed a higher separation capacity and was able to separate seven related substances from the active pharmaceutical ingredient, while the cellulose-based column enabled the baseline resolution of six impurities from ezetimibe. Generally, the accuracy of predicted retention times was lower for the polysaccharide CSP, which could indicate the presence of additional secondary interactions between the analytes and the CSP. It was also demonstrated that the combination of mechanistic modeling and an experimental design approach can be applied to method development on CSPs in reverse-phase mode. The applicability of the methods was tested on spiked artificial placebo samples, while intraday and long-term (2 years) method repeatability was also challenged through comparing the obtained retention times and resolution values. The results indicated the excellent robustness of the selected setpoints. Overall, our findings indicate that the chiral columns could offer orthogonal selectivity to traditional reverse-phase columns for the separation of structurally similar compounds.

Optimization of chromatographic conditions via Box‒Behnken design in RP-HPLC-PDA method development for the estimation of folic acid and methotrexate in bulk and tablets

Simultaneous estimation of folic acid and methotrexate in bulk and tablet dosage form by RP-HPLC-PDA was conducted via Box‒Behnken design application. Three-factor numerical values were finalized from the graphical and numerical optimization with built-in ANOVA in BBD. Sharp and symmetric peaks were observed at 4.138 and 6.929 min for folic acid and methotrexate, respectively. The mobile phase composition was methanol and 0.1% formic acid in water with a ratio of 31:69 and a flow rate of 1.1 ml/min. Both drugs were detected at a wavelength of 291 nm. The developed method was validated according to ICH guidelines. The results of the validation parameters were within acceptable limits. Stress stability studies have been performed under acidic, alkali, oxidation, neutral and photolytic conditions. Three different brand-marketed tablets were assessed with the developed method (MGXT, FOLTNAX and TRUXOFOL). In the tablet formulations, chromatogram percentages of folic acid and methotrexate were calculated at 99.13% and 99.50 in MGXT, 99.17% and 99.47 in FOLTNAX, and 99.91 and 100.05 in TRUXOFOL.