Power of the Dissolution Test in Distinguishing a Change in Dosage Form Critical Quality Attributes

Quality by Design Perspective for Designing Foam-based Formulation: Current State of Art

Foam-based delivery systems contain one or more active ingredients and dispersed solid or liquid components that transform into gaseous form when the valve is actuated. Foams are an attractive and effective delivery approach for medical, cosmetic, and pharmaceutical uses. The foams-based delivery systems are gaining attention due to ease of application as they allow direct application onto the affected area of skin without using any applicator or finger, hence increasing the compliance and satisfaction of the patients. In order to develop foam-based delivery systems with desired qualities, it is vital to understand which type of material and process parameters impact the quality features of foams and which methodologies may be utilized to investigate foams. For this purpose, Quality-by-Design (QbD) approach is used. It aids in achieving quality-based development during the development process by employing the QbD concept. The critical material attributes (CMAs) and critical process parameters (CPPs) were discovered through the first risk assessment to ensure the requisite critical quality attributes (CQAs). During the initial risk assessment, the high-risk CQAs were identified, which affect the foam characteristics. In this review, the authors discussed the various CMAs, CPPs, CQAs, and risk factors associated in order to develop an ideal foam-based formulation with desired characteristics.

Dissolution Profiles Comparison Using Conventional and Bias Corrected and Accelerated f2 Bootstrap Approaches with Different Software's: Impact of Variability, Sample Size and Number of Bootstraps

Dissolution profiles comparison is an important element in order to support biowaivers, scale-up and post approval changes and site transfers. Highly variable dissolution can possess significant challenges for comparison and f2 bootstrap approach can be utilized in such cases. However, availability of different types of f2 and confidence intervals (CI) methods indicates necessity to understand each type of calculation thoroughly. Among all approaches, bias corrected and accelerated (BCa) can be an attractive choice as it corrects the bias and skewness of the distribution. In this manuscript, we have performed comparison of highly variable dissolution data using various software's by adopting percentile and BCa CI approaches. Diverse data with different variability's, number of samples and bootstraps were evaluated with JMP, DDSolver, R-software, SAS and PhEq. While all software's yielded similar observed f2 values, differences in lower percentile CI was observed. BCa with R-software and JMP provided superior lower percentile as compared to other computations. Expected f2 recommended by EMA has resulted as stringent criteria as compared to estimated f2. No impact of number of bootstraps on similarity analysis was observed whereas number of samples increased chance of acceptance. Variability has impacted similarity outcome with estimated f2 but chance of acceptance enhanced with BCa approach. Further, freely available R-software can be of attractive choice due to computation of various types of f2, percentile and BCa intervals. Overall, this work can enable regulatory submissions to enhance probability of similarity through appropriate selection of number of samples, technique based on variability of dissolution data.

Discriminative Dissolution Method Development Through an aQbD Approach

Using a one-factor-at-a-time approach for dissolution method and discrimination analysis can be time-consuming and may not yield the optimal and discriminative method. To address this, we have developed a two-stage workflow for the dissolution method development followed by demonstration of discrimination power through an analytical Quality by Design (aQbD) approach. In the first stage, an optimal dissolution method was achieved by determining the method operable design region (MODR) through a design of experiment study of the high-risk method-related parameters. In the second stage, we established a Formulation-Discrimination Correlation Diagram strategy to examine the method discrimination capability, through which one can determine the method discriminative design region (MDDR) and visualize the impact of each formulation parameter and their interactions on dissolution. The application of aQbD principles into a workflow provides a scientific-driven guidance for robust method development and demonstrating discrimination power for dissolution methods.

Crystallinity: A Complex Critical Quality Attribute of Amorphous Solid Dispersions

Does the performance of an amorphous solid dispersion rely on having 100% amorphous content? What specifications are appropriate for crystalline content within an amorphous solid dispersion (ASD) drug product? In this Perspective, the origin and significance of crystallinity within amorphous solid dispersions will be considered. Crystallinity can be found within an ASD from one of two pathways: (1) incomplete amorphization, or (2) crystal creation (nucleation and crystal growth). While nucleation and crystal growth is the more commonly considered pathway, where crystals originate as a physical stability failure upon accelerated or prolonged storage, manufacturing-based origins of crystallinity are possible as well. Detecting trace levels of crystallinity is a significant analytical challenge, and orthogonal methods should be employed to develop a holistic assessment of sample properties. Probing the impact of crystallinity on release performance which may translate to meaningful clinical significance is inherently challenging, requiring optimization of dissolution test variables to address the complexity of ASD formulations, in terms of drug physicochemical properties (e.g., crystallization tendency), level of crystallinity, crystal reference material selection, and formulation characteristics. The complexity of risk presented by crystallinity to product performance will be illuminated through several case studies, highlighting that a one-size-fits-all approach cannot be used to set specification limits, as the risk of crystallinity can vary widely based on a multitude of factors. Risk assessment considerations surrounding drug physicochemical properties, formulation fundamentals, physical stability, dissolution, and crystal micromeritic properties will be discussed.

Progressive tools and critical strategies for development of best fit PBPK model aiming better in vitro-in vivo correlation

Nowadays, conducting discriminative dissolution experiments employing physiologically based pharmacokinetic modeling (PBPK) or physiologically based biopharmaceutical modeling (PBBM) is gaining significant importance in quantitatively predicting oral absorption of drugs. Mechanistic understanding of each process involved in drug absorption and its impact on the performance greatly facilitates designing a formulation with high confidence. Unfortunately, the biggest challenge scientists are facing in current days is the lack of standardized protocol for integrating dissolution experiment data during PBPK modeling. However, in vitro-in vivo drug release interrelation can be improved with the consideration and development of appropriate biorelevant dissolution media that closely mimic physiological conditions. Multiple reported dissolution models have described nature and functionality of different regions of the gastrointestinal tract (GI) to more accurately design discriminative dissolution media. Dissolution experiment data can be integrated either mechanistically or without a mechanism depending primarily on the formulation type, biopharmaceutics classification system (BCS) class and particle size of the drug substance. All such parameters are required to be considered for selecting the appropriate functions during PBPK modeling to produce a best fit model. The primary focus of this review is to critically discuss various progressive dissolution models and tools, existing challenges and approaches for establishing best fit PBPK model aiming better in vitro-in vivo correlation (IVIVC). Strategies for proper selection of dissolution models as an input function in PBPK/PBBM modeling have also been critically discussed. Logical and scientific pathway for selection of different type of functions and integration events in the commercially available in silico software has been described through case studies.

Discriminative Dissolution Method Using the Open-Loop Configuration of the USP IV Apparatus to Compare Dissolution Profiles of Metoprolol Tartrate Immediate-Release Tablets: Use of Kinetic Parameters

The use of the USP IV apparatus (flow-through cell) has gained acceptance in recent years due to its versatility and ability to discriminate due to its hydrodynamic conditions. Therefore, the objective of the present study was to develop a discriminative dissolution method in the USP IV apparatus using the open-loop configuration, as well as to propose a method to compare non-cumulative dissolution profiles obtained in the open-loop configuration considering kinetic parameters and validate its predictive power through its comparison with independent and dependent methods using five commercial immediate-release tablet drugs (one reference drug and four generic drugs) of metoprolol tartrate as a model drug. The comparison of the non-accumulated dissolution profiles consisted of determining the geometric ratio of Cmax, AUC0∞, AUC0Cmax, and Tmax (kinetic parameters) of the generic/reference drugs, whereby generic drugs "C" and "D" presented the highest probability of similarity since their 90% confidence intervals were included, or they were very close to the acceptance interval (80.00-125.00%). These results were consistent with the f2, bootstrap f2, and dissolution efficiency approaches (independent models). In conclusion, the proposed comparison method can be an important tool to establish similarity in dissolution profiles and to facilitate the development/selection of new formulations and positively ensure bioequivalence in clinical studies.

Effect of pH, Ionic Strength and Agitation Rate on Dissolution Behaviour of 3D-Printed Tablets, Tablets Prepared from Ground Hot-Melt Extruded Filaments and Physical Mixtures

With the current focus on 3D-printing technologies, it is essential to understand the processes involved in such printing methods and approaches to minimize the variability in dissolution behaviour to achieve better quality control outcomes. For this purpose, two formulations of theophylline tablets were prepared using hydroxypropyl cellulose (HPC) and ethyl cellulose (EC). Among the two types of tablets, three different methods (physical mixture (PM), hot-melt extrusion (HME) and 3D-printing fused deposition modelling (FDM)) were applied and their dissolution behaviours were studied under various conditions using a biodissolution tester. This was carried out at pH values of 1.2, 2.2, 5.8, 6.8, 7.2 and 7.5, mimicking the medium in the gastrointestinal tract. Dissolution tests under two dipping rates (10 dpm and 20 dpm) and two ionic strengths (0.2 M and 0.4 M) were conducted to mimic fed and fasting conditions. The dissolution efficiency (DE%), release rate, similarity factor (f₂) and difference factor (f₁) were calculated. When comparing the DE%, the formulation containing EC showed less sensitivity to changes in the dipping rate and ionic strength compared to the HPC formulation. As for the manufacturing method, 3D-printing FDM could improve the robustness of the dissolution behaviour of both formulations to dipping rate changes. However, for ionic strength changes, the effect of the manufacturing method was dependent on the formulation composition. For example, the 3D-printed tablets of the HPC formulation were more sensitive to changes in ionic strength compared to the EC-containing formulation. The release mechanism also changed after the thermal process, where n values in the Korsmeyer-Peppas model were much higher in the printing and HME methods compared to the PM. Based on the formulation composition, the 3D-printing method could be a good candidate method for tablets with a robust dissolution behaviour in the GI tract. Compared to HPC polymers, using hydrophobic EC polymers in printable formulations can result in a more robust dissolution behaviour in fed and fasting states.

Application of Liquid Chromatography Coupled to Mass Spectrometry in Quality Assessment of Dietary Supplements—A Case Study of Tryptophan Supplements: Release Assay, Targeted and Untargeted Studies

Dietary supplements are widely consumed in the EU and the USA. Based on their similarity to pharmaceuticals, consumers mistakenly believe that dietary supplements have also been approved for safety and efficacy. However, in the absence of mandatory testing, data on supplement quality is scarce. Thus, we applied liquid chromatography coupled with tandem mass spectrometry to analyse the quality of dietary supplements containing tryptophan (Trp). We examined 22 supplements in tablets or capsules, produced in the USA, Great Britain, Germany, France, Czech Republic, and Poland. Trp release, crucial for bioavailability and efficiency, was assessed. Additionally, we performed a qualitative analysis of the main ingredient and screened for contaminants. Among the contaminants, we detected Trp’s metabolites, condensation products of Trp and carbonyl compounds, Trp degradation products, degradation products of kynurenine, and other contaminants such as glucosamine and melatonin. The main ingredient content was in the range of 55–100% in capsules and 69–87% in tablets. Surprisingly, almost no Trp release was noted from some supplements. Our study confirms the need to advance research on supplements. We believe that the high-quality analysis of supplements based on reliable analytical techniques will be an important contribution to the discussion on the regulatory framework of these products.

Tablet formulation development focusing on the functional behaviour of water uptake and swelling

The functional behaviour of tablets is strongly influenced by their manufacturing process and the choice of excipients. Water uptake and swelling are prerequisites for tablet disintegration, dispersion and hence active pharmaceutical ingredient (API) dissolution. High proportions of polymeric excipients in tablets, which are typically used as API carriers in amorphous solid dispersions (ASDs), may be challenging due to the formation of a gelling polymer network (GPN). In this study, systematic investigations into the formulation development of tablets containing polymeric and other excipients are performed by water uptake and swelling analysis. The impact of tablet composition and porosity as well as pH of the test medium are investigated. The pH affects the analysis results for Eudragit L100-55 and Eudragit EPO. HPMC and Kollidon VA64 inhibit water uptake and swelling of tablets due to the formation of a GPN. High tablet porosity, coarse particle size of the polymer and the addition of fillers and disintegrants can reduce the negative impact of a GPN on tablet performance. The application of lubricants slows down the analysed processes. Water uptake and swelling data are fitted to an empirical model obtaining four characteristic parameters to facilitate the simple quantitative assessment of varying tablet formulations and structural properties.

Influence of basket mesh size on the hydrodynamics in the USP rotating basket dissolution testing Apparatus 1

The USP Apparatus 1 (rotating basket), typically used to assess drug product reproducibility and evaluate oral solid dosage forms performance, consists of a cylindrical glass vessel with a hemispherical bottom and a wire basket rotating at constant speed. Baskets with different wire openings can be used in alternative to the standard mesh opening (40-mesh) in order to discriminate between drug formulations during early stage of drug product development. Any changes introduced by different basket geometries can potentially and significantly impact the system hydrodynamics and cause variability of results, thus affecting product quality. In this work, Particle Image Velocimetry (PIV) was used to experimentally quantify the velocity distribution in the USP rotating basket Apparatus 1 using baskets of different mesh sizes (10-, 20-, and 40-mesh size) under the typical operating conditions described in dissolution testing procedures. Similar flow patterns were observed in all cases. However, the radial and axial velocities in the USP Apparatus 1 generally increased with increasingly larger openings of the basket mesh. Increasing the basket agitation speed also resulted in an overall increase in the velocities, especially below in the innermost core region below the basket, where drug fragments typically reside. More importantly, the flow entering and leaving the baskets was quantified from the velocity profiles in the immediate vicinity of the baskets. It was found that the flow increased significantly with increasingly larger mesh openings, which can, in turn, promote faster dissolution of the oral solid dosage forms, thus affecting drug dissolution profiles. Hence, the selection of the basket mesh size must be carefully considered during drug product development.

Investigating In Vitro and Ex Vivo Properties of Artemether/Lumefantrine Double-Fixed Dose Combination Lipid Matrix Tablets Prepared by Hot Fusion

Highly lipophilic antimalarial drugs, artemether and lumefantrine, whilst an effective fixed-dose combination treatment to lower the malarial disease burden, are therapeutically hindered by low aqueous solubility and varied bioavailability. This work investigates the plausibility of directly compressed lipid matrix tablets, their role as lipid-based formulations and their future standing as drug delivery systems. Lipid matrix tablets were manufactured from solid lipid dispersions in various lipid:drug ratios employing hot fusion—the melt mixing of highly lipophilic drugs with polymer(s). Sequential biorelevant dissolution media, multiple mathematical models and ex vivo analysis utilizing porcine tissue samples were employed to assess drug release kinetics and more accurately predict in vitro performance. Directly compressed stearic acid tablets in a 0.5:1 lipid:drug ratio were deemed optimal within investigated parameters. Biorelevant media was of immense value for artemether release analysis, with formulation SA0.5C1 (Stearic Acid:double fixed dose in a 0.5:1 ratio (i.e., Stearic acid 70 mg + Lumefantrine 120 mg + Artemether 20 mg); CombiLac^® as filler (q.s.); and 1% w/w magnesium stearate) yielding a higher percentage of artemether release (97.21%) than the commercially available product, Coartem^® (86.12%). However, dissolution media lacked the specificity to detect lumefantrine. Nonetheless, stearic acid lipid:drug ratios governed drug release mechanisms. This work demonstrates the successful utilization of lipids as pharmaceutical excipients, particularly in the formulation of lipid matrix tablets to augment the dissolution of highly lipophilic drugs, and could thus potentially improve current malarial treatment regimens.

Amorphous Solid Dispersions Containing Residual Crystallinity: Competition Between Dissolution and Matrix Crystallization

Crystallinity in an amorphous solid dispersion (ASD) may negatively impact dissolution performance by causing lost solubility advantage and/or seeding crystal growth leading to desupersaturation. The goal of the study was to evaluate underlying dissolution and crystallization mechanisms resulting from residual crystallinity contained within bicalutamide (BCL)/polyvinylpyrrolidone vinyl acetate copolymer (PVPVA) ASDs produced by hot melt extrusion (HME). In-line Raman spectroscopy, polarized light microscopy, and scanning electron microscopy were used to characterize crystallization kinetics and mechanisms. The fully amorphous ASD (0% crystallinity) did not dissolve completely, and underwent crystallization to the metastable polymorph (form 2), initiating in the amorphous matrix at the interface of the amorphous solid with water. Under non-sink conditions, higher extents of supersaturation were achieved because dissolution initially proceeded unhindered prior to nucleation. ASDs containing residual crystallinity had markedly reduced supersaturation. Solid-mediated crystallization (matrix crystallization) consumed the amorphous solid, growing the stable polymorph (form 1). Under sink conditions, both the fully amorphous ASD and crystalline physical mixture achieve faster release than the ASDs containing residual crystallinity. In the latter systems, matrix crystallization leads to highly agglomerated crystals with high relative surface area. Solution-mediated crystallization was not a significant driver of concentration loss, due to slow crystal growth from solution in the presence of PVPVA. The high risk stemming from residual crystallinity in BCL/PVPVA ASDs stems from (1) fast matrix crystallization propagating from crystal seeds, and (2) growth of the stable crystal form. This study has implications for dissolution performance outcomes of ASDs containing residual crystallinity.

Development and Validation of a Discriminatory Dissolution Model for an Immediately Release Dosage Form by DOE and Statistical Approaches

A discriminatory dissolution model was built through DOE with multivariate analysis of variance (MANOVA) and multiple linear regression (MLR) modeling to assess dissolution operational space for a highly water soluble immediate-release solid dosage drug product. The dissolution was utilized in the following five aspects: (1) understand the impact of individual variables and their interactions on dissolution performance through effect analysis; (2) explain the lack of discriminatory power of the initial dissolution condition used in early phase development by prediction profiler; (3) predict discriminatory dissolution operational space to differentiate photo degraded drug products from control with contour profiler analysis; (4) validate by the external experimental data acquired with the initial nondiscriminatory dissolution condition and the predicted discriminatory dissolution condition, followed by model independent statistical analysis (e.g., f2); and (5) establish correlation of the discriminatory dissolution with disintegration. The selected discriminatory dissolution method was validated by demonstrating accuracy, precision and linearity, specificity, repeatability, intermediate precision, stability, filter verification, and robustness.

An improved method for the simultaneous determination of water uptake and swelling of tablets

Water uptake and swelling of tablets are processes occurring during active pharmaceutical ingredient (API) release. Thereby, disintegration is promoted and the enhanced exposure of API surface area to the release medium facilitates API dissolution. An experimental set-up for the simultaneous and time-resolved determination of water uptake and swelling of tablets has been developed. Water uptake was determined with a balance and swelling was determined with a camera. To validate the gravimetrical analysis, real-time water uptake measurements with inert test specimens were performed. The standard deviation of these measurements was considered to depict precision. A complementary gravimetrical analysis was employed to determine accuracy. For both, precision and accuracy, a maximum deviation of 6% was found. An algorithm for the symmetry-based 3D volume reconstruction was applied to obtain volumes of the tablets from 2D images. X-ray micro computed tomography was used to validate the accuracy and the determined volumes were in good accordance within 6% deviation. A case study with binary formulations of a filler and disintegrants confirmed reproducibility and demonstrated the ability of the method to discriminate formulation characteristics, such as disintegrant type, composition and porosity for water uptake and swelling with the necessary temporal resolution.

An In Vitro-In Vivo Simulation Approach for the Prediction of Bioequivalence

The aim of this study was to develop a new in vitro–in vivo simulation (IVIVS) approach in order to predict the outcome of a bioequivalence study. The predictability of the IVIVS procedure was evaluated through its application in the development process of a new generic product of amlodipine/irbesartan/hydrochlorothiazide. The developed IVIVS methodology is composed of three parts: (a) mathematical description of in vitro dissolution profiles, (b) mathematical description of in vivo kinetics, and (c) development of joint in vitro–in vivo simulations. The entire programming was done in MATLAB^® and all created scripts were validated through other software. The IVIVS approach can be implemented for any number of subjects, clinical design, variability and can be repeated for thousands of times using Monte Carlo techniques. The probability of success of each scenario is recorded and finally, an overall assessment is made in order to select the most suitable batch. Alternatively, if the IVIVS shows reduced probability of BE success, the R&D department is advised to reformulate the product. In this study, the IVIVS approach predicted successfully the BE outcome of the three drugs. During the development of generics, the IVIVS approach can save time and expenses.

Potential Application of USP Paddle and Basket Dissolution Methods in Discriminating for Portioned Moist Snuff and Snus Smokeless Tobacco Products

The focus of the study was to develop discriminatory dissolution methods for portioned snus and moist snuff sub-categories of smokeless tobacco products (STPs) using USP basket and paddle apparatuses. Skoal Classic Wintergreen (SCW) and CORESTA CRP1.1 pouches were used as test products. The dissolution was performed at 10, 20, 30, 40, and 50 rpm basket or paddle speed in 500 ml artificial saliva pH 6.8. The products were also characterized for assay, pH, particle size, and loss on drying. The dissolution profiles were evaluated for amount/% of nicotine dissolved, time to reach plateau, and profiles comparison by f2 and f1 factors. The nicotine assay was 13.3 ± 0.2 and 7.6 ± 0.1 mg/pouch for SCW and CRP1.1, respectively. The nicotine dissolved in 30 min from SCW and CRP1.1 were 38.4-81.8 and 37.6-88.1, and 50.5-64.9 and 72.3-92.1% by paddle and basket methods, respectively. The f2 and f1 values were ≤ 39.2 and ≥ 42.1 and ≤ 43.2 and ≥ 34.1 for basket methods and paddle methods. RSD were less than 20% at all points of dissolution profiles, and dissolution plateau were achieved in 30 min at some of the tested conditions. In summary, dissolution methods based on basket and paddle can be used as a performance test for STPs.

Automatic Dissolution Testing with High-Temporal Resolution for Both Immediate-Release and Fixed-Combination Drug Tablets

Dissolution testing plays many important roles throughout the pharmaceutical industry, from the research and development of drug products to the control and evaluation of drug quality. However, it is a challenging task to perform both high-efficient separation and high-temporal detection to achieve accurate dissolution profile of each active ingredient dissolved from a drug tablet. In our study, we report a novel non-manual-operation method for performing the automatic dissolution testing of drug tablets, by combining a program-controlled sequential analysis and high-speed capillary electrophoresis for efficient separation of active ingredients. The feasibility of the method for dissolution testing of real drug tablets as well as the performance of the proposed system has been demonstrated. The accuracy of drug dissolution testing is ensured by the excellent repeatability of the sequential analysis, as well as the similarity of the evaluation of dissolution testing. Our study show that the proposed method is capable to achieve simultaneous dissolution testing of multiple ingredients, and the matrix interferences can be avoided. Therefore it is of potential valuable applications in various fields of pharmaceutical research and drug regulation.

Benefits of Fractal Approaches in Solid Dosage Form Development

Pharmaceutical formulations are complex systems consisting of active pharmaceutical ingredient(s) and a number of excipients selected to provide the intended performance of the product. The understanding of materials' properties and technological processes is a requirement for building quality into pharmaceutical products. Such understanding is gained mostly from empirical correlations of material and process factors with quality attributes of the final product. However, it seems also important to gain knowledge based on mechanistic considerations. Promising is here to study morphological and/or topological characteristics of particles and their aggregates. These geometric aspects must be taken into account to better understand how product attributes emerge from raw materials, which includes, for example, mechanical tablet properties, disintegration or dissolution behavior. Regulatory agencies worldwide are promoting the use of physical models in pharmaceutics to design quality into a final product. This review deals with pharmaceutical applications of theoretical models, focusing on percolation theory, fractal, and multifractal geometry. The use of these so-called fractal approaches improves the understanding of different aspects in the development of solid dosage forms, for example by identifying critical drug and excipient concentrations, as well as to study effects of heterogeneity on dosage form performance. The aim is to link micro- and macrostructure to the emerging quality attributes of the pharmaceutical solid dosage forms as a strategy to enhance mechanistic understanding and to advance pharmaceutical development and manufacturing processes.