Design of Experiments in Pharmaceutical Development

A review of the use of central composite design in the optimization of procedures aiming at food chemical analysis

Design of experiments is a branch of chemometrics that encompasses the study and application of experimental matrices to study and optimize systems, procedures, and processes to improve their performances. The central composite design (CCD) stands out among the experimental matrices available for this task. This design has been widely applied in various areas of human knowledge due to its flexibility and robustness. This review addresses the use of CCD as a matrix to optimize analytical methods to improve their characteristics in determining analytes in food samples. Its principles and characteristics, its association with the response surface methodology, and recent applications of this matrix in developing analytical methods aimed at food analysis will also be addressed.

Antioxidant and anticancer activities of hesperetin and its novel formulations in KB cells

This study aimed to formulate the hesperetin nanostructured lipid carriers (NLCs) containing oro-mucosal gel for its activity assessment on the KB cell line. NLCs were prepared with glyceryl monostearate, oleic acid, and lecithin using a modified constant-temperature emulsification technique. The particle size analysis, in vitro drug release studies, etc., of prepared NLCs were evaluated. The formulated gels were analyzed with respect to spreadability, extrudability, swelling index, texture analysis, etc. The particle size, polydispersity index, zeta potential, and drug entrapment of nanocarriers were recorded to be 221.733 ± 61.536 nm, 0.381 ± 0.091, - 51.433 ± 4.143 mV, and 89.29%, respectively. The optimized NLCs in 24 h released 87.14 ± 6.62% of the drug. The round shape of NLCs was noticed with scanning electron microscopy. The pH, spreadability, extrudability, swelling index, content uniformity, and drug release studies of hesperetin NLCs-containing gel (HNG) were found to be 6.81 ± 0.04, 2.49 ± 0.04 cm.mg/s, 539.04 ± 32.88 g/cm2, 4.27 ± 0.47, 107.98 ± 1.93%, and 90.17 ± 6.67% (in 48 h), respectively. The developed formulations showed promising in vitro anticancer and antioxidant activities. HNP results authorize that the formulation may be beneficial for the treatment of oral cancer.

Reducing dimethyl sulfoxide content in Jurkat cell formulations suitable for cryopreservation

Cell-based medicinal products (CBMPs) are usually cryopreserved in formulations containing up to 10 % dimethyl sulfoxide (Me2SO) at temperatures below -145 °C. Although Me2SO effectively protects cells during the freezing process, it can be damaging to cells at ambient temperatures and lead to side effects in patients. The aim of this study was to reduce the amount of Me2SO in cryopreservation formulations for an immortalized T cell line (Jurkat cells). A design of experiment (DoE) approach was applied for formulation development using seven different excipients, i.e., Me2SO, trehalose, sorbitol, proline, ectoine, poloxamer 188 (P188) and poly vinyl pyrrolidone 40 (PVP). A DoE model was generated to predict optimal formulations resulting in a high post-thaw viability and a high glass transition temperature of the formulation to allow for frozen storage without the use of liquid nitrogen. Subsequently a stability study was performed with promising lead candidates over three months at storage temperatures of -145 °C, -80 °C, -40 °C. Three benchmark solutions were used, i.e., Cryostor CS10, CryoSOfree as well as 10 % Me2SO in Roswell Park Memorial Institute Medium (RPMI). The excipient affecting the post-thaw viability of Jurkat cells the most was, as expected, Me2SO, which led to increased viabilities at higher concentrations. Most formulations resulted in similar viabilities for cells stored at -145 °C and -80 °C, whereas samples stored at -40 °C did not survive. In general, benchmark formulations resulted in slightly higher viabilities than the tested formulations. Furthermore, cell samples stored at -80 °C were recultivated in cell culture and the viability was assessed after 24h. The cell viability after 24h was much lower compared to the cells analyzed directly post-thaw, indicating that freeze-thaw damages continue to unfold after thawing. In summary, several promising excipients and combinations thereof, e.g., trehalose and PVP, were identified for the cryopreservation of Jurkat cells with reduced concentrations of Me2SO or Me2SO-free cryopreservation. Additionally, storage at -80 °C is possible for the developed formulations.

Optimizing N,N,N-trimethyl chitosan synthesis: A design of experiments (DoE) approach

This study aimed to optimize the synthesis of trimethyl chitosan (TMC) with a high degree of N,N,N-trimethylation (DTM) through a one-step procedure, minimizing reagent use, reaction time, and avoiding O-methylation, using the Design of Experiments (DoE) approach. Initially, sequential designs were done. Following the determination of the initial conditions a Fractional Factorial Design was used, investigating methyl iodide (MeI) and NaHCO3 molar ratios, temperature, and reaction time on DTM. MeI and NaHCO3 molar ratios were found to be significant (p-values equal to 0.02 and 0.02, respectively), the reaction temperature (p = 0.04) displayed a non-linear effect, while the reaction time was found to be non-significant (p = 0.93). Finally, a Full Factorial Design was done to optimize temperature and base addition methods. Incremental addition of the base was determined to be feasible without affecting the DTM, thereby preventing any viscosity-related problems. DTM was achieved up to 72 % in a one-step procedure, with no O-methylation. These optimized conditions offer a cost-effective, one-step synthesis method for TMC production, holding significant promise for industrial applications by avoiding multistep reactions, ensuring minimal reagent use, and preventing O-methylation. The findings mark a substantial advancement in TMC synthesis, presenting a streamlined and efficient approach with substantial practical implications for process development.

Optimizing the Extraction Efficiency of Flaxseed Gum Using a Response Surface Methodology Approach

The extraction of gum from natural raw materials is of increasing importance in various industries, including food, pharmaceuticals, and cosmetics, particularly due to their emulsifying properties and potential applications as stabilizers and thickeners. This study presents an insight on the influence of changing parameters like reagents and operating condition on yield and some properties of the flax (Linum usitatissimum L.) seed gum. The extraction conditions were meticulously examined using a full factorial design, highlighting the significant impact of pretreatment, seed preparation, and solvent selection on the extraction yield. A response surface methodology (RSM) was then applied to optimize the water/benzoic acid ratio of the pretreatment step, the ethyl alcohol/water ratio, and the medium pH of the extraction method, resulting in a maximum yield of 14.47%. Furthermore, detailed analyses of the chemical and emulsifying properties of the gum were conducted showing emulsifying capacities over 94%, offering promising application prospects, particularly in the food industry.

QbD-Guided Traditional Chinese Medicine Manufacturing Process: Development and Optimization of Fluid-Bed Granulation and Drying Processes for Xiaochaihu Capsules

Traditional methods of producing Xiaochaihu (XCH) capsules, a traditional Chinese medicine, are time-consuming, costly, and labor-intensive, which is not conductive to modernizing TCM. To address the challenges, new fluid-bed granulation and drying processes with water as the binder were developed and optimized guided by the principles of Quality by Design (QbD) in this study. Ishikawa diagram was applied to conduct a preliminary risk assessment, followed by 6-factor definitive screening design (DSD) serving as a QbD statistical tool to develop and optimize the new processes. Multiple potential factors and interactions were studied with a small number of experiments using the DSD. This study identified critical process parameters (CPPs), established quadratic regression models to reveal CPP-critical quality attributes (CQAs) connections within the DSD framework, and defined a dependable design space. Processes conducted by parameter combinations in the design space produced qualified granules with production yield and raw material utilization higher than 90% and moisture content lower than 4%. Furthermore, quantitative analysis of baicalin of all the granules ensured qualified contents of active pharmaceutical ingredient. The newly developed processes for XCH capsules, with advantages of shorter time, environmental friendliness, and decreased cost, exemplify the effective application of QbD and design of experiments (DoE) methodologies in the modernization of TCM manufacturing processes.

Pathological and Therapeutic Significance of Tumor-Derived Extracellular Vesicles in Cancer Cell Migration and Metastasis

The infiltration of primary tumors and metastasis formation at distant sites strongly impact the prognosis and the quality of life of cancer patients. Current therapies including surgery, radiotherapy, and chemotherapy are limited in targeting the complex cell migration mechanisms responsible for cancer cell invasiveness and metastasis. A better understanding of these mechanisms and the development of new therapies are urgently needed. Extracellular vesicles (EVs) are lipid-enveloped particles involved in inter-tissue and inter-cell communication. This review article focuses on the impact of EVs released by tumor cells, specifically on cancer cell migration and metastasis. We first introduce cell migration processes and EV subtypes, and we give an overview of how tumor-derived EVs (TDEVs) may impact cancer cell migration. Then, we discuss ongoing EV-based cancer therapeutic approaches, including the inhibition of general EV-related mechanisms as well as the use of EVs for anti-cancer drug delivery, focusing on the harnessing of TDEVs. We propose a protein-EV shuttle as a route alternative to secretion or cell membrane binding, influencing downstream signaling and the final effect on target cells, with strong implications in tumorigenesis. Finally, we highlight the pitfalls and limitations of therapeutic EV exploitation that must be overcome to realize the promise of EVs for cancer therapy.

Design of experiment (DoE) as a quality by design (QbD) tool to optimise formulations of lipid nanoparticles for nose-to-brain drug delivery

INTRODUCTION

The nose-to-brain route has been widely investigated to improve drug targeting to the central nervous system (CNS), where lipid nanoparticles (solid lipid nanoparticles - SLN and nanostructured lipid carriers - NLC) seem promising, although they should meet specific criteria of particle size (PS) <200 nm, polydispersity index (PDI) <0.3, zeta potential (ZP) ~|20| mV and encapsulation efficiency (EE) >80%. To optimize SLN and NLC formulations, design of experiment (DoE) has been recommended as a quality by design (QbD) tool.

AREAS COVERED

This review presents recently published work on the optimization of SLN and NLC formulations for nose-to-brain drug delivery. The impact of different factors (or independent variables) on responses (or dependent variables) is critically analyzed.

EXPERT OPINION

Different DoEs have been used to optimize SLN and NLC formulations for nose-brain drug delivery, and the independent variables lipid and surfactant concentration and sonication time had the greatest impact on the dependent variables PS, EE, and PDI. Exploring different DoE approaches is important to gain a deeper understanding of the factors that affect successful optimization of SLN and NLC and to facilitate future work improving machine learning techniques.

Loteprednol-Loaded Nanoformulations for Corneal Delivery by Quality-by-Design Concepts: Optimization, Characterization, and Anti-inflammatory Activity

Loteprednol etabonate (LE) is a topical corticosteroid that uses inflammatory conditions of the eye. It has a low ocular bioavailability and side effects such as corneal disorder, eye discharge, and ocular discomfort. Therefore, it was decided to select the delivery systems, which are solid lipid nanoparticles (SLN), nanostructured lipid carriers (NLC), and nanoemulsion (NE). Design of experiments (DoE) of SLN, NLC, and NE formulations were formulated by using the quality by design (QbD) approach. Precirol® ATO 5 and oleic acid were used as solid and liquid lipids, respectively, in SLN, NLC, and NE formulations. Physiochemical characterization was performed on the formulations. The optimized formulations' inflammatory effects have been appraised on human corneal epithelial cells employing the ELISA test. Physicochemical characterization studies and inflammatory effects were appraised. The sizes of optimized formulations of SLN, NLC, and NE were 86.19 nm, 82.38 nm, and 126.35 nm, respectively, with minimum polydispersity. The release behavior of the formulations is composed of both diffusion and erosion. ELISA test results proved that the formulations significantly reduced IL-1 and IL-6 levels (p < 0.05). D-optimal mixture experimental design allowed us to develop the most precise formulations of SLN, NLC, and NE. Furthermore, the optimized formulations could be promising candidates for treating an inflammation-based corneal disease of the eye.

A Brief Introduction to Chemical Reaction Optimization

From the start of a synthetic chemist's training, experiments are conducted based on recipes from textbooks and manuscripts that achieve clean reaction outcomes, allowing the scientist to develop practical skills and some chemical intuition. This procedure is often kept long into a researcher's career, as new recipes are developed based on similar reaction protocols, and intuition-guided deviations are conducted through learning from failed experiments. However, when attempting to understand chemical systems of interest, it has been shown that model-based, algorithm-based, and miniaturized high-throughput techniques outperform human chemical intuition and achieve reaction optimization in a much more time- and material-efficient manner; this is covered in detail in this paper. As many synthetic chemists are not exposed to these techniques in undergraduate teaching, this leads to a disproportionate number of scientists that wish to optimize their reactions but are unable to use these methodologies or are simply unaware of their existence. This review highlights the basics, and the cutting-edge, of modern chemical reaction optimization as well as its relation to process scale-up and can thereby serve as a reference for inspired scientists for each of these techniques, detailing several of their respective applications.

Quality by Design: A Suitable Methodology in Industrial Pharmacy for Costa Rican Universities

This review aims to present the Quality by Design (QbD) model as a suitable methodology to perform research in the academic Costa Rican institutions that teach Pharmacy. Pubmed, Science Direct, and Google Scholar databases were screened for original research papers and review papers published not more than ten years ago. Institutional repositories from the different universities were reviewed as well. The QbD model stands out as a great methodology for carrying out research projects regarding Pharmaceutical Sciences, but especially for Industrial Pharmacy, where it has contributed in terms of formulation development, manufacturing, and quality control. Academic research based on this model enables the training and development of practical, scientific, and leadership skills in Industrial Pharmacy students. The generated knowledge can be shared in classrooms, which represents an ideal environment to communicate research results and to foster collaborative work between researchers, professors, and students. Moreover, research performed through a QbD approach increases the confidence shown by the industrial sector and health regulatory authorities in the quality of the research, products, and knowledge that are developed and created in an Academy. As a result, the implementation of the model has allowed the creation, transfer, and materialization of knowledge from the Costa Rican Academy to different local pharmaceutical industries.

Complying with the Guideline for Quality and Equivalence for Topical Semisolid Products: The Case of Clotrimazole Cream

Semisolids constitute a significant proportion of topical pharmaceutical dosage forms available on the market, with creams being considered profitable systems for releasing active substances into the skin. This work aimed at the development of a generic Clotrimazole topical cream, based on the assumptions that assist the development of such formulations. First, the critical parameters to obtain a final formulation as similar as possible to the reference product were defined. Then, the percentages of cetyl palmitate and octyldodecanol were identified as critical variables and chosen for optimization in further studies. A "quality by design" approach was then used to identify the effect of process variability on the structural and functional similarity (Q3) of the generic product qualitatively (Q1) and quantitatively (Q2). A two-factor central composite orthogonal design was applied and eleven different formulations were developed and subjected to physicochemical characterization and product performance studies. The results were used to estimate the influence of the two variables in the variation of the responses, and to determine the optimum point of the tested factors, using a design space approach. Finally, an optimized formulation was obtained and analysed in parallel with the reference. The obtained results agreed with the prediction of the chemometric analysis, validating the reliability of the developed multivariate models. The in vitro release and permeation results were similar for the reference and the generic formulations, supporting the importance of interplaying microstructure properties with product performance and stability. Lastly, based on quality targets and response constraints, optimal working conditions were successfully achieved.

Quality-by-design in hot melt extrusion based amorphous solid dispersions: An industrial perspective on product development

An industrially feasible approach to overcome the solubility and bioavailability limitations of poorly soluble active pharmaceutical ingredients is the development of amorphous solid dispersions (ASDs) using hot-melt extrusion (HME) technique. The application of Quality by Design (QbD) had a profound impact on the development of HME-based ASDs. The formulation and process optimization of ASDs manufactured via HME techniques require an understanding of critical quality attributes, critical material attributes, critical process parameters, risk assessment tools, and experimental designs. The knowledge gained from each of these QbD elements helps ensure the consistency of product quality. The selection and implementation of appropriate Design of Experiments (DoE) methodology to screen and optimize the formulation and process variables remain a major challenge. This review provides a comprehensive overview on QbD concepts in HME-based ASDs with an emphasis on DoE methodologies. Further, the information provided in this review can assist researchers in selecting a suitable design with optimal experimental conditions. Specifically, this review has focused on the prediction of drug-polymer miscibility, the elements and sequence of QbD, and various screening and optimization designs, to provide insights into the formulation and process variables that are encountered routinely in the production of HME-based ASDs.

Comprehensive Study of Atorvastatin Nanostructured Lipid Carriers through Multivariate Conceptualization and Optimization

The aim of the current study is to establish a comprehensive experimental design for the screening and optimization of Atorvastatin-loaded nanostructured lipid carriers (AT-NLCs). Initially, combined D-optimal screening design was applied to find the most significant factors affecting AT-NLCs properties. The studied variables included mixtures of solid and liquid lipids, the solid/liquid lipid ratio, surfactant type and concentration, homogenization speed as well as sonication time. Then, the variables homogenization speed (A), the ratio of solid lipid/liquid lipid (B), and concentration of the surfactant (C) were optimized using a central composite design. Particle size, polydispersity index, zeta potential, and entrapment efficiency were chosen as dependent responses. The optimized AT-NLCs demonstrated a nanometric size (83.80 ± 1.13 nm), Polydispersity Index (0.38 ± 0.02), surface charge (-29.65 ± 0.65 mV), and high drug incorporation (93.1 ± 0.04%). Fourier Transform Infrared Spectroscopy (FTIR) analysis showed no chemical interaction between Atorvastatin and the lipid mixture. Differential Scanning Calorimetry (DSC) analysis of the AT-NLCs suggested the transformation of Atorvastatin crystal into an amorphous state. Administration of the optimized AT-NLCs led to a significant reduction (p < 0.001) in serum levels of rats' total cholesterol, triglycerides, and low-density lipoproteins. This change was histologically validated by reducing the relevant steatosis of the liver.

Hot Melt Extrusion Processing Parameters Optimization

The aim of this study was to demonstrate the impact of processing parameters of the hot-melt extrusion (HME) on the pharmaceutical formulation properties. Carbamazepine (CBZ) was selected as a model water-insoluble drug. It was incorporated into Soluplus®, which was used as the polymeric carrier, to produce a solid dispersion model system. The following HME-independent parameters were investigated at different levels: extrusion temperature, screw speed and screw configuration. Design of experiment (DOE) concept was applied to find the most significant factor with minimum numbers of experimental runs. A full two-level factorial design was applied to assess the main effects, parameter interactions and total error. The extrudates’ CBZ content and the in vitro dissolution rate were selected as response variables. Material properties, including melting point, glass transition, and thermal stability, and polymorphs changes were used to set the processing range. In addition, the extruder torque and pressure were used to find the simplest DOE model. Each change of the parameter showed a unique pattern of dissolution profile, indicating that processing parameters have an influence on formulation properties. A simple, novel and two-level factorial design was able to evaluate each parameter effect and find the optimized formulation. Screw configuration and extrusion temperature were the most affecting parameters in this study.