Amorphous solid dispersions: An update for preparation, characterization, mechanism on bioavailability, stability, regulatory considerations and marketed products

Polymeric Amorphous Solid Dispersions of Dasatinib: Formulation and Ecotoxicological Assessment

Dasatinib (DAS), a potent anticancer drug, has been subjected to formulation enhancements due to challenges such as significant first-pass metabolism, poor absorption, and limited oral bioavailability. To improve its release profile, DAS was embedded in a matrix of the hydrophilic polymer polyvinylpyrrolidone (PVP). Drug amorphization was induced in a planetary ball mill by solvent-free co-grinding, facilitating mechanochemical activation. This process resulted in the formation of amorphous solid dispersions (ASDs). The ASD capsules exhibited a notable enhancement in the release rate of DAS compared to capsules containing the initial drug. Given that anticancer drugs often undergo limited metabolism in the body with unchanged excretion, the ecotoxicological effect of the native form of DAS was investigated as well, considering its potential accumulation in the environment. The highest ecotoxicological effect was observed on the bacteria Vibrio fischeri, while other test organisms (bacteria Pseudomonas putida, microalgae Chlorella sp., and duckweed Lemna minor) exhibited negligible effects. The enhanced drug release not only contributes to improved oral absorption but also has the potential to reduce the proportion of DAS that enters the environment through human excretion. This comprehensive approach highlights the significance of integrating advances in drug development while considering its environmental implications.

Physicochemical Characterization and In Vitro Activity of Poly(ε-Caprolactone)/Mycophenolic Acid Amorphous Solid Dispersions

The obtention of amorphous solid dispersions (ASDs) of mycophenolic acid (MPA) in poly(ε-caprolactone) (PCL) is reported in this paper. An improvement in the bioavailability of the drug is possible thanks to the favorable specific interactions occurring in this system. Differential scanning calorimetry (DSC) was used to investigate the miscibility of PCL/MPA blends, measuring glass transition temperature (Tg) and analyzing melting point depression to obtain a negative interaction parameter, which indicates the development of favorable inter-association interactions. Fourier transform infrared spectroscopy (FTIR) was used to analyze the specific interaction occurring in the blends. Drug release measurements showed that at least 70% of the drug was released by the third day in vitro in all compositions. Finally, preliminary in vitro cell culture experiments showed a decreased number of cancerous cells over the scaffolds containing MPA, presumably arising from the anti-cancer activity attributable to MPA.

Understanding the Interaction of Thermal, Rheological, and Mechanical Parameters Critical for the Processability of Polyvinyl Alcohol-Based Systems during Hot Melt Extrusion

Hot melt extrusion (HME) is a common manufacturing process used in the pharmaceutical industry to improve the solubility of poorly soluble active pharmaceutical ingredients (API). The goal is to create an amorphous solid dispersion (ASD) where the amorphous form of the API is stabilized within a polymer matrix. Traditionally, the development of pharmaceutically approved polymers has focused on requirements such as thermal properties, solubility, drug-polymer interactions, and biocompatibility. The mechanical properties of the material have often been neglected in the design of new polymers. However, new downstream methods require more flexible polymers or suitable plasticizer polymer combinations. In this study, two grades of the polymer polyvinyl alcohol (PVA), which is already established for HME, are investigated in terms of their mechanical, rheological, and thermal properties. The mechanical properties of the extruded filaments were tested by the three-point bending test. The rheological behavior was analyzed by oscillating plate measurements. Thermal analysis was performed by differential scanning calorimetry (DSC). In addition, the solid and liquid plasticizers mannitol, sorbitol, triacetin, triethyl citrate, polyethylene glycol, and glycerol were evaluated for use with PVA and their impact on the polymer properties was elaborated. Finally, the effects of the plasticizers are compared to each other, and the correlations are analyzed statistically using principal component analysis (PCA). Thereby, a clear ranking of the plasticizer effects was established, and a deeper understanding of the polymer-plasticizer interactions was created.

Development of Ternary Amorphous Solid Dispersions Manufactured by Hot-Melt Extrusion and Spray-Drying─Comparison of In Vitro and In Vivo Performance

Producing amorphous solid dispersions (ASDs) by hot-melt extrusion (HME) is favorable from an economic and ecological perspective but also limited to thermostable active pharmaceutical ingredients (APIs). A potential technology shift from spray-drying to hot-melt extrusion at later stages of drug product development is a desirable goal, however bearing the risk of insufficient comparability of the in vitro and in vivo performance of the final dosage form. Hot-melt extrusion was performed using API/polymer/surfactant mixtures with hydroxypropyl methylcellulose acetate succinate (HPMCAS) as the polymer and evaluated regarding the extrudability of binary and ternary amorphous solid dispersions (ASDs). Additionally, spray-dried ASDs were produced, and solid-state properties were compared to the melt-extruded ASDs. Tablets were manufactured of a ternary ASD lead candidate comparing their in vitro dissolution and in vivo performance. The extrudability of HPMCAS was improved by adding a surfactant as plasticizer, thereby lowering the high melt-viscosity. d-α-Tocopheryl polyethylene glycol succinate (TPGS) as surfactant showed the most similar solid-state properties between spray-dried and extruded ASDs compared to those of poloxamer 188 and sodium dodecyl sulfate. The addition of TPGS, however, barely affected API/polymer interactions. The in vitro dissolution experiment and in vivo dog study revealed a higher drug release of tablets manufactured from the spray-dried ASD compared to the melt-extruded ASD; this was attributed to the different particle size. We could further demonstrate that the drug release can be controlled by adjusting the particle size of melt-extruded ASDs leading to a similar release profile compared to tablets containing the spray-dried dispersion, which confirmed the feasibility of a technology shift from spray-drying to HME upon drug product development.

Novel rivaroxaban-loaded microsphere systems with different surface microstructure for enhanced oral bioavailability

This study compares rivaroxaban-loaded polymeric microsphere systems with three types of surface microstructure. Three types of polymeric microspheres loaded with rivaroxaban were fabricated using a spray-drying technique: solvent-evaporated, surface-attached, and solvent-wet microspheres, depending on whether the drug and additives used are soluble in the solvent. The solvent-evaporated and surface-attached microspheres had a rivaroxaban/polyvinylpyrrolidone/sodium lauryl sulfate (SLS) weight ratio of 1/0.25/2.2, and the solvent-wetted microspheres contained rivaroxaban/polyvinyl alcohol/SLS in equal weight ratio (1/0.25/2). The physicochemical properties of the microspheres were evaluated using scanning electron microscopy, powder X-ray diffraction, differential scanning calorimetry, and particle size distribution analysis. The aqueous solubility and dissolution rate of rivaroxaban in the three types of microspheres were compared to those of the drug powder. The solvent-evaporated, surface-attached, and solvent-wetted microspheres were approximately 208, 140, and 172 times as soluble as the drug powder, and the final dissolution rate (120 min) was approximately 5, 2, and 4 times that of the drug powder, respectively. In addition, the oral bioavailability increased by approximately 2, 1.3, and 1.6 times compared to that of the drug powder (area under drug concentration-time curve: 2101.3 ± 314.8, 1325.2 ± 333.3, and 1664.0 ± 102.6 h·ng/mL, respectively). Finally, the solvent-evaporated microspheres showed the greatest improvement (solvent evaporating microspheres > solvent wetted microspheres > surface-attached microspheres ≥ drug powder). Therefore, the solvent-evaporated microspheres may represent a novel oral dosage form that improves the oral bioavailability of rivaroxaban, a poorly soluble drug.

Recent developments in the use of nanocrystals to improve bioavailability of APIs

Nanocrystals refer to materials with at least one dimension smaller than 100 nm, composing of atoms arranged in single crystals or polycrystals. Nanocrystals have significant research value as they offer unique advantages over conventional pharmaceutical formulations, such as high bioavailability, enhanced targeting selectivity and controlled release ability and are therefore suitable for the delivery of a wide range of drugs such as insoluble drugs, antitumor drugs and genetic drugs with broad application prospects. In recent years, research on nanocrystals has been progressively refined and new products have been launched or entered the clinical phase of studies. However, issues such as safety and stability still stand that need to be addressed for further development of nanocrystal formulations, and significant gaps do exist in research in various fields in this pharmaceutical arena. This paper presents a systematic overview of the advanced development of nanocrystals, ranging from the preparation approaches of nanocrystals with which the bioavailability of poorly water-soluble drugs is improved, critical properties of nanocrystals and associated characterization techniques, the recent development of nanocrystals with different administration routes, the advantages and associated limitations of nanocrystal formulations, the mechanisms of physical instability, and the enhanced dissolution performance, to the future perspectives, with a final view to shed more light on the future development of nanocrystals as a means of optimizing the bioavailability of drug candidates. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology.

Development of Aerosol Dry Powder Chemotherapeutic-Loaded Microparticles for the Treatment of Lung Cancer

Lung cancer is the leading cause of cancer-related deaths worldwide, resulting in the highest mortality rates among both men and women with respect to all other types of cancer. Difficulties in treating lung cancer arise from late-stage diagnoses and tumor heterogeneity and current treatment involves a combination of chemotherapeutics, surgery, and radiation. Chemotherapeutics administered systemically can lead to undesirable side effects and severe off-site toxicity. For example, chronic administration of the chemotherapeutic doxorubicin (DOX) leads to cardiotoxicity, thereby limiting its long-term use. Systemic administration of the highly lipophilic molecule paclitaxel (PTX) is hindered by its water solubility, necessitating the use of solubilizing agents, which can induce side effects. Thus, in this investigation, formulations consisting of spray-dried microparticles (MP) containing DOX and PTX were produced to be administered as dry powder aerosols directly to the lungs. Acetalated dextran (Ac-Dex) was used as the polymer in these formulations, as it is a biocompatible and biodegradable polymer that exhibits pH-responsive degradation. Solid-state characterization revealed that DOX and PTX remained in solubility favoring amorphous states in the MP formulations and that both drugs remained thermally stable throughout the spray drying process. In vitro release studies demonstrated the pH sensitivity of the formulations due to the use of Ac-Dex, as well as the release of both therapeutics over the course of at least 48 h. In vitro aerosol dispersion studies demonstrated that both formulations exhibited suitable aerosol dispersion properties for deep lung delivery.

An innovative carrier for the formulation of amorphous solid dispersion by hot-melt extrusion with no further downstream processes: a case study with indomethacin

The aim of this work was to study the possibility to use SepitrapTM as a carrier for the formulation of amorphous solid dispersions by HME (hot melt extrusion) processing aiming solubility enhancement of poorly water-soluble drugs. SepitrapTM is a microencapsulated powder solubilizer designed to simplify the manufacture of drugs in oral solid forms, not yet tested for this purpose. The performance of SepitrapTM was evaluated in HME processing for amorphous solid dispersions of poorly-water soluble drugs with indomethacin as a model drug. The study was conducted using a twin-screw extruder, two compositions of SepitrapTM and different loads of indomethacin, demonstrating that SepitrapTM could represent a new range of carriers for amorphous solid dispersions for HME processing, reducing necessary downstream steps such as grinding.

Drug-drug co-amorphous systems: An emerging formulation strategy for poorly water-soluble drugs

Overcoming the poor water solubility of small-molecule drugs is a major challenge in the development of clinical pharmaceuticals. Amorphization of crystalline drugs is a highly effective strategy to improve their aqueous solubility. However, amorphous drugs are thermodynamically unstable and likely to crystallize during manufacturing and storage. Recently, drug-drug co-amorphous systems have emerged as a novel strategy to not only enable enhanced dissolution and physical stability of the individual drugs within the system but also to provide a strategy for combination therapy of the same or different clinical indications. This review serves to highlight advances in the methods used to manufacture and characterize drug-drug co-amorphous systems, summarize drug-drug co-amorphous applications reported in recent decades, and provide an outlook on future possibilities and perspectives.

Liquid API feeding in pharmaceutical HME: Novel options in solid dosage manufacturing

Hot melt extrusion (HME) is a common unit operation. It is broadly applicable in the pharmaceutical industry and can be implemented in a continuous manufacturing line. However, the conventional way of active pharmaceutical ingredient (API) feeding with a pre-blend consisting of a powdered API and a polymer does not allow the flexibility and agility to adjust the process parameters, which is generally an essential part of continuous manufacturing. In addition, this method of API feeding may result in the segregation of the individual powder components or agglomeration of highly cohesive materials, leading to an inhomogeneous API content in the extrudates, especially at low doses. In this study, the universal applicability of liquid side feeding in pharmaceutical HME was demonstrated using various APIs suspended or dissolved in water and fed as suspension or undersaturated, supersaturated, and highly concentrated solutions into anterior parts of the extruder. The extrudates were characterized in terms of their API content, residual moisture content, and solid-state of the API embedded in the polymer. The results show that a uniform API content without major deviations can be obtained via this method. Furthermore, the residual moisture content of the extrudates was low enough to have no significant influence on further processing of the final dosage form. In summary, this advanced way of feeding allows an accurate, flexible, and agile feeding of APIs, facilitating the production of personalized final dosage forms and a novel option to link the manufacturing of the drug substance and the drug product.

Comprehensive evaluation of polymer types and ratios in Spray-Dried Dispersions: Compaction, Dissolution, and physical stability

Amorphous solid dispersion (ASD) is a well-established strategy for enhancing the solubility and bioavailability of poorly soluble drugs. A significant portion of ASD products are in tablet form. However, the influence of common polymers and drug loading on the manufacturability of ASD tablets remains underexplored. This study focuses on investigating spray-dried ASDs from a tableting perspective by evaluating their physiochemical and mechanical properties. Itraconazole (ITZ) and indomethacin (IND), at the drug loadings ranging from 10% to 50%, were prepared with two polymers, hydroxypropyl methylcellulose acetate succinate (HPMCAS) and polyvinylpyrrolidone (PVP), serving as representative systems. Our findings revealed that increasing the drug loading resulted in a decreased surface area in ITZ-HPMCAS, IND-HPMCAS, and IND-PVP ASDs. However, this trend was not observed in ITZ-PVP dispersions, possibly due to the morphological disparities. Compaction results demonstrated that tabletability improved with decreasing drug loadings, except for ITZ-PVP dispersions. A partial least square analysis underscored particle surface area as the key factor influencing the tensile strength of ASD tablets. Additionally, our study disclosed that ITZ-PVP ASDs exhibited the worst release profiles and stability performance. The comprehensive journey from characterizing ASD particles to analyzing their compaction behavior and investigating drug release and physical stability offered profound insights into the attributes crucial for the downstream processing of amorphous pharmaceuticals.

Advancing Drug Delivery Paradigms: Polyvinyl Pyrolidone (PVP)-Based Amorphous Solid Dispersion for Enhanced Physicochemical Properties and Therapeutic Efficacy

BACKGROUND

The current challenge in drug development lies in addressing the physicochemical issues that lead to low drug effectiveness. Solubility, a crucial physicochemical parameter, greatly influences various biopharmaceutical aspects of a drug, including dissolution rate, absorption, and bioavailability. Amorphous solid dispersion (ASD) has emerged as a widely explored approach to enhance drug solubility.

OBJECTIVE

The objective of this review is to discuss and summarize the development of polyvinylpyrrolidone (PVP)-based amorphous solid dispersion in improving the physicochemical properties of drugs, with a focus on the use of PVP as a novel approach.

METHODOLOGY

This review was conducted by examining relevant journals obtained from databases such as Scopus, PubMed, and Google Scholar, since 2018. The inclusion and exclusion criteria were applied to select suitable articles.

RESULTS

This study demonstrated the versatility and efficacy of PVP in enhancing the solubility and bioavailability of poorly soluble drugs. Diverse preparation methods, including solvent evaporation, melt quenching, electrospinning, coprecipitation, and ball milling are discussed for the production of ASDs with tailored characteristics.

CONCLUSION

PVP-based ASDs could offer significant advantages in the formulation strategies, stability, and performance of poorly soluble drugs to enhance their overall bioavailability. The diverse methodologies and findings presented in this review will pave the way for further advancements in the development of effective and tailored amorphous solid dispersions.

The Impact of Various Poly(vinylpyrrolidone) Polymers on the Crystallization Process of Metronidazole

In this paper, we propose one-step synthetic strategies for obtaining well-defined linear and star-shaped polyvinylpyrrolidone (linPVP and starPVP). The produced macromolecules and a commercial PVP K30 with linear topology were investigated as potential matrices for suppressing metronidazole (MTZ) crystallization. Interestingly, during the formation of binary mixtures (BMs) containing different polymers and MTZ, we found that linear PVPs exhibit maximum miscibility with the drug at a 50:50 weight ratio (w/w), while the star-shaped polymer mixes with MTZ even at a 30:70 w/w. To explain these observations, comprehensive studies of MTZ-PVP formulations with various contents of both components were performed using Fourier-transform infrared spectroscopy, differential scanning calorimetry, and X-ray diffraction. The obtained results clearly showed that the polymer's topology plays a significant role in the type of interactions occurring between the matrix and MTZ. Additionally, we established that for MTZ-PVP 50:50 and 75:25 w/w BMs, linear polymers have the most substantial impact on inhibiting the crystallization of API. The star-shaped macromolecule turned out to be the least effective in stabilizing amorphous MTZ at these polymer concentrations. Nevertheless, long-term structural investigations of the MTZ-starPVP 30:70 w/w system (which is not achievable for linear PVPs) demonstrated its complete amorphousness for over one month.

Material-Sparing Feasibility Screening for Hot Melt Extrusion

Hot melt extrusion (HME) offers a high-throughput process to manufacture amorphous solid dispersions. A variety of experimental and model-based approaches exist to predict API solubility in polymer melts, but these methods are typically aimed at determining the thermodynamic solubility and do not take into account kinetics of dissolution or the associated degradation of the API during thermal processing, both of which are critical considerations in generating a successful amorphous solid dispersion by HME. This work aims to develop a material-sparing approach for screening manufacturability of a given pharmaceutical API by HME using physically relevant time, temperature, and shear. Piroxicam, ritonavir, and phenytoin were used as model APIs with PVP VA64 as the dispersion polymer. We present a screening flowchart, aided by a simple custom device, that allows rapid formulation screening to predict both achievable API loadings and expected degradation from an HME process. This method has good correlation to processing with a micro compounder, a common HME screening industry standard, but only requires 200 mg of API or less.

Microscopic Cracks Modulate Nucleation and Solid-State Crystallization Tendency of Amorphous Celecoxib

Drugs have been classified as fast, moderate, and poor crystallizers based on their inherent solid-state crystallization tendency. Differential scanning calorimetry-based heat-cool-heat protocol serves as a valuable tool to define the solid-state crystallization tendency. This classification helps in the development of strategies for stabilizing amorphous drugs. However, microscopic characteristics of the samples were generally overlooked during these experiments. In the present study, we evaluated the influence of microscopic cracks on the crystallization tendency of a poorly water-soluble model drug, celecoxib. Cracks developed in the temperature range of 0-10 °C during the cooling cycle triggered the subsequent crystallization of the amorphous phase. Nanoindentation study suggested minimal differences in mechanical properties between samples, although the cracked sample showed relatively inhomogeneous mechanical properties. Nuclei nourishment experiments suggested crack-assisted nucleation, which was supported by Raman data that revealed subtle changes in intermolecular interactions between cracked and uncracked samples. Celecoxib has been generally classified as class II, i.e., a drug with moderate crystallization tendency. Interestingly, classification of amorphous celecoxib may change depending on the presence or absence of cracks in the amorphous sample. Hence, subtle events such as microscopic cracks should be given due consideration while defining the solid-state crystallization tendency of drugs.

Fused Deposition Modelling 3D printing and solubility improvement of BCS II and IV active ingredients - A narrative review

In the field of pharmaceutical research and development, Fused Deposition Modelling (FDM) 3D printing (3DP) has aroused growing interest within the last ten years. The use of thermoplastic polymers, combined with the melting process of the raw materials, offers the possibility of manufacturing amorphous solid dispersions (ASDs). In the pharmaceutical industry, the formulation of an ASD is a widely used strategy to improve the solubility of poorly soluble drugs (classified by the Biopharmaceutical Classification System (BCS) as class II and IV). In this review, an analysis of studies that have developed a FDM printed form containing a BCS class II or IV active substance was performed. The focus has been placed on the evaluation of the solid state of the active molecules (crystalline or amorphous) and on the study of their dissolution profile. Thus, the aim of this work is to highlight the interest of FDM 3DP to induce the amorphisation phenomenon of Class II and IV active substances by forming an ASD, and as result improving their solubility.

Sulfur dioxide-releasing polymeric micelles based on modified hyaluronic acid for combined cancer therapy

In this study, an amphiphilic polymer mPEG-HA(SA)-DNs was designed and synthesized to fabricate a multifunctional micellar system to enhance the therapeutic efficacy and reduce the toxic effect of paclitaxel (PTX). The polymer was prepared by introducing mPEG, stearic acid (SA) and 2,4-dinitrobenzenesulfonic acid (DNs) to the backbone of hyaluronic acid (HA). With above modifications, the fabricated micelles could encapsulate PTX in the core with high drug loading. The optimized PTX-loaded micelles had a mean size of 158.3 nm. Upon the effect of mPEG, the mPEG-HA(SA)-DNs micelles reduced the non-specific protein adsorption. In vitro drug release study revealed the excellent glutathione (GSH)-triggered PTX release behavior of the micelles. Moreover, GSH could trigger the detachment of DNs segment from mPEG-HA(SA)-DNs, and result in the release of SO2. In vitro and in vivo antitumor efficacy studies demonstrated that the PTX-loaded mPEG-HA(SA)-DNs micelles exhibited outstanding tumor suppression effect. The micelles would be potential carriers for combination cancer therapy by SO2 and PTX.

One-Step Preparation of Fiber-Based Chlorzoxazone Solid Dispersion by Centrifugal Spinning

An amorphous fiber-based solid dispersion of chlorzoxazone was prepared for the first time by employing centrifugal spinning, using polyvinylpyrrolidone as the fiber-forming polymer. After optimization of the spinning parameters, the obtained fibers were characterized using a set of analytical techniques, both in a solid- and solution-state. Morphological characterization revealed a slightly aligned, defect-free fibrous structure with an average fiber diameter of d = 3.07 ± 1.32 μm. The differential scanning calorimetric results indicated a crystalline-to-amorphous transition of the active substance during the centrifugal spinning process, while gas chromatographic determinations revealed a residual ethanol content of 0.42 ± 0.04%. UV spectroscopy indicated the incorporation of chlorzoxazone in the fibrous structures, with an average active substance content of 15.91 ± 0.36 w/w%. During small-volume dissolution studies, the prepared fiber mats presented immediate disintegration upon contact with the dissolution media, followed by rapid dissolution of the active substance, with 84.8% dissolved at 1 min and 93.7% at 3 min, outperforming the micronized, pure chlorzoxazone. The obtained results indicate that centrifugal spinning is a low-cost, high-yield, viable alternative to the currently used methods to prepare fiber-based amorphous solid dispersions of poorly soluble drugs. The prepared chlorzoxazone-loaded microfibers could be used as a buccal dosage form for the systematic delivery of chlorzoxazone and could potentially lead to a rapid onset of action and longer efficacy of the muscle relaxant drug.

Phase homogeneity in ternary amorphous solid dispersions and its impact on solubility, dissolution and supersaturation - Influence of processing and hydroxypropyl cellulose grade

As performance of ternary amorphous solid dispersions (ASDs) depends on the solid-state characteristics and polymer mixing, a comprehensive understanding of synergistic interactions between the polymers in regard of dissolution enhancement of poorly soluble drugs and subsequent supersaturation stabilization is necessary. By choosing hot-melt extrusion (HME) and vacuum compression molding (VCM) as preparation techniques, we manipulated the phase behavior of ternary efavirenz (EFV) ASDs, comprising of either hydroxypropyl cellulose (HPC)-SSL or HPC-UL in combination with Eudragit® L 100-55 (EL 100-55) (50:50 polymer ratio), leading to single-phased (HME) and heterogeneous ASDs (VCM). Due to higher kinetic solid-state solubility of EFV in HPC polymers compared to EL 100-55, we visualized higher drug distribution into HPC-rich phases of the phase-separated ternary VCM ASDs via confocal Raman microscopy. Additionally, we observed differences in the extent of phase-separation in dependence on the selected HPC grade. As HPC-UL exhibited decisive lower melt viscosity than HPC-SSL, formation of partially miscible phases between HPC-UL and EL 100-55 was facilitated. Consequently, as homogeneously mixed polymer phases were required for optimal extent of solubility improvement, the manufacturing-dependent differences in dissolution performances were smaller using HPC-UL, instead of HPC-SSL, i.e. using HPC-UL was less demanding on shear stress provided by the process.

Effect of Buffer pH and Concentration on the Dissolution Rates of Sodium Indomethacin-Copovidone and Indomethacin-Copovidone Amorphous Solid Dispersions

The incorporation of counterions into amorphous solid dispersions (ASDs) has been proven to be effective for improving the dissolution rates of ionizable drugs in ASDs. In this work, the effect of dissolution buffer pH and concentration on the dissolution rate of indomethacin-copovidone 40:60 (IMC-PVPVA, w/w) ASD with or without incorporated sodium hydroxide (NaOH) was studied by surface area-normalized dissolution to provide further mechanistic understanding of this phenomenon. Buffer pH from 4.7 to 7.2 and concentration from 20 to 100 mM at pH 5.5 were investigated. As the buffer pH decreased, the IMC dissolution rate from both ASDs decreased. Compared to IMC-PVPVA ASD, the dissolution rate decrease from IMCNa-PVPVA ASD was more resistant to the decrease of buffer pH. In contrast, while buffer concentration had a negligible impact on the IMC dissolution rate from IMC-PVPVA ASD, the increase of buffer concentration significantly reduced the IMC dissolution rate from IMCNa-PVPVA ASD. Surrogate evaluation of microenvironment pH modification by the dissolution of IMCNa-PVPVA ASD demonstrated the successful elevation of buffer microenvironment pH and the suppression of such pH elevation by the increase of buffer concentration. These results are consistent with the hypothesis that the dissolution rate enhancement by the incorporation of counterions originates from the enhanced drug solubility by ionization and the modification of diffusion layer pH in favor of drug dissolution. At the studied drug loading (∼40%), relatively congruent release between IMC and PVPVA was observed when IMC was ionized in ASD or in solution, highlighting the importance of studying the ionization effect on the congruent release of ASDs, especially when drug ionization is expected in vivo. Overall, this work further supports the application of incorporating counterions into ASDs for improving the dissolution rates of ionizable drugs when enabling formulation development is needed.

The applications of machine learning to predict the forming of chemically stable amorphous solid dispersions prepared by hot-melt extrusion

Amorphous solid dispersion (ASD) is one of the most important strategies to improve the solubility and dissolution rate of poorly water-soluble drugs. As a widely used technique to prepare ASDs, hot-melt extrusion (HME) provides various benefits, including a solvent-free process, continuous manufacturing, and efficient mixing compared to solvent-based methods, such as spray drying. Energy input, consisting of thermal and specific mechanical energy, should be carefully controlled during the HME process to prevent chemical degradation and residual crystallinity. However, a conventional ASD development process uses a trial-and-error approach, which is laborious and time-consuming. In this study, we have successfully built multiple machine learning (ML) models to predict the amorphization of crystalline drug formulations and the chemical stability of subsequent ASDs prepared by the HME process. We utilized 760 formulations containing 49 active pharmaceutical ingredients (APIs) and multiple types of excipients. By evaluating the built ML models, we found that ECFP-LightGBM was the best model to predict amorphization with an accuracy of 92.8%. Furthermore, ECFP-XGBoost was the best in estimating chemical stability with an accuracy of 96.0%. In addition, the feature importance analyses based on SHapley Additive exPlanations (SHAP) and information gain (IG) revealed that several processing parameters and material attributes (i.e., drug loading, polymer ratio, drug's Extended-connectivity fingerprints (ECFP) fingerprints, and polymer's properties) are critical for achieving accurate predictions for the selected models. Moreover, important API's substructures related to amorphization and chemical stability were determined, and the results are largely consistent with the literature. In conclusion, we established the ML models to predict formation of chemically stable ASDs and identify the critical attributes during HME processing. Importantly, the developed ML methodology has the potential to facilitate the product development of ASDs manufactured by HME with a much reduced human workload.

Strategies to improve the stability of amorphous solid dispersions in view of the hot melt extrusion (HME) method

Oral administration of drugs is preferred over other routes for several reasons: it is non-invasive, easy to administer, and easy to store. However, drug formulation for oral administration is often hindered by the drug's poor solubility, which limits its bioavailability and reduces its commercial value. As a solution, amorphous solid dispersion (ASD) was introduced as a drug formulation method that improves drug solubility by changing the molecular structure of the drugs from crystalline to amorphous. The hot melt extrusion (HME) method is emerging in the pharmaceutical industry as an alternative to manufacture ASD. However, despite solving solubility issues, ASD also exposes the drug to a high risk of crystallisation, either during processing or storage. Formulating a successful oral administration drug using ASD requires optimisation of the formulation, polymers, and HME manufacturing processes applied. This review presents some important considerations in ASD formulation, including strategies to improve the stability of the final product using HME to allow more new drugs to be formulated using this method.

Comparative Evaluation of Particle Size Reduction, Salt Formation, and Amorphous Formulation on the Biopharmaceutical Performance of a Weak Base Drug Candidate

Various approaches have been developed to enhance the solubility or dissolution rate for the delivery of poorly water-soluble molecules. In this work, guided by an in silico solubility sensitivity analysis for oral absorption, a comparative assessment of the biopharmaceutical performance of a jet-milled free base, a tosylate salt, and a 50:50 (w/w) amorphous solid dispersion (ASD) with hydroxypropyl methylcellulose acetate succinate (HPMCAS) of a weak base drug candidate, GDC-3280, was conducted. Successful particle size reduction without amorphization or form change was confirmed for the jet-milled free base. The potential of solubility enhancement and desupersaturation risk were identified for tosylate salt and ASD formulation by measurements of tosylate salt solubility product constant (Ksp) and amorphous solubility of GDC-3280. In vitro dissolution testing demonstrated dissolution rate improvement for the jet-milled free base when compared with the unmilled free base and confirmed solubility enhancement followed by desupersaturation for GDC-3280 tosylate salt and ASD formulation. A crystallization inhibitor, hydroxypropyl methylcellulose (HPMC), was found to slow down the desupersaturation of tosylate salt solution, providing general insights for the development of pharmaceutical salts with disproportionation risks. Finally, a pharmacokinetic study in dogs showed that the in vivo exposure increased by 1.7- to 2-fold for the tosylate salt and ASD formulation compared with the jet-milled free base, consistent with the in silico solubility sensitivity analysis for the fraction of drug absorbed. Overall, this work provides insights into the evaluation of multiple formulation approaches for enhancing the biopharmaceutical performance of poorly water-soluble drugs.

Design of Redispersible High-Drug-Load Amorphous Formulations: Impact of Ionic vs Nonionic Surfactants on Processing and Performance

Amorphous solid dispersions (ASDs) are an enabling formulation approach used to enhance bioavailability of poorly water-soluble molecules in oral drug products. Drug-rich amorphous nanoparticles generated in situ during ASD dissolution maintain supersaturation that drives enhanced absorption. However, in situ formation of nanoparticles requires large quantities of polymers to release drugs rapidly, resulting in an ASD drug load <25%. Delivering directly engineered drug-rich amorphous nanoparticles can reduce the quantities of polymers significantly without sacrificing bioavailability. Preparation of 90% drug-load amorphous nanoparticles (ANPs) of <300 nm diameter using solvent/antisolvent nanoprecipitation, organic solvent removal, and spray drying was demonstrated previously on model compound ABT-530 with Copovidone and sodium dodecyl sulfate (anionic). In this work, nonionic surfactant d-α-tocopheryl polyethylene glycol succinate (Vitamin E TPGS, or TPGS) was used to prepare ANPs as a comparison. Characterization of ANPs by dynamic light scattering, filtrate potency assay, scanning electron microscopy, and differential scanning calorimetry revealed differences in surface properties of nanoparticles afforded by surfactants. This work demonstrates the importance of understanding the impact of the stabilizing agents on nanoparticle behavior when designing a high-drug-load amorphous formulation for poorly water-soluble compounds as well as the impact on redispersion.

Utilizing Drug Amorphous Solid Dispersions for the Preparation of Dronedarone per os Formulations

Dronedarone (DRN), an antiarrhythmic drug, exhibits potent pharmacological effects in the management of cardiac arrhythmias. Despite its therapeutic potential, DRN faces formulation challenges due to its low aqueous solubility. Hence, the present study is dedicated to the examination of amorphous solid dispersions (ASDs) as a strategic approach for enhancing the solubility of DRN. Initially, the glass forming ability (GFA) of API was assessed alongside its thermal degradation profile, and it was revealed that DRN is a stable glass former (GFA III compound) that remains thermally stable up to approximately 200 °C. Subsequently, five commonly used ASD matrix/carriers, i.e., hydroxypropyl methylcellulose (HPMC), povidone (PVP), copovidone (PVP/VA), Soluplus® (SOL), and Eudragit® E PO (EPO), were screened for the formation of a DRN-based ASD using film casting and solvent shift methods, along with miscibility evaluation measurements. SOL proved to be the most promising matrix/carrier among the others, and, hence, was used to prepare DRN ASDs via the melt-quench method. The physicochemical characterization of the prepared systems (via pXRD) revealed the complete amorphization of the API within the matrix/carrier, while the system was physically stable for at least three months after its preparation. In vitro release studies for the ASDs, conducted under non-sink conditions, revealed the sustained supersaturation of the drug for at least 8 h. Finally, the use of attenuated total reflectance (ATR) FTIR spectroscopy showed the formation of a strong molecular interaction between the drug molecules and SOL.

Sugars and Polyols of Natural Origin as Carriers for Solubility and Dissolution Enhancement

Crystalline carriers such as dextrose, sucrose, galactose, mannitol, sorbitol, and isomalt have been reported to increase the solubility, and dissolution rates of poorly soluble drugs when employed as carriers in solid dispersions (SDs). However, synthetic polymers dominate the preparation of drugs: excipient SDs have been created in recent years, but these polymer-based SDs exhibit the major drawback of recrystallisation upon storage. Also, the use of high-molecular-weight polymers with increased chain lengths brings forth problems such as increased viscosity and unnecessary bulkiness in the resulting dosage form. An ideal SD carrier should be hydrophilic, non-hygroscopic, have high hydrogen-bonding propensity, have a high glass transition temperature (Tg), and be safe to use. This review discusses sugars and polyols as suitable carriers for SDs, as they possess several ideal characteristics. Recently, the use of low-molecular-weight excipients has gained much interest in developing SDs. However, there are limited options available for safe, low molecular excipients, which opens the door again for sugars and polyols. The major points of this review focus on the successes and failures of employing sugars and polyols in the preparation of SDs in the past, recent advances, and potential future applications for the solubility enhancement of poorly water-soluble drugs.

HPMCAS-Based Amorphous Solid Dispersions in Clinic: A Review on Manufacturing Techniques (Hot Melt Extrusion and Spray Drying), Marketed Products and Patents

Today, therapeutic candidates with low solubility have become increasingly common in pharmaceutical research pipelines. Several techniques such as hot melt extrusion, spray drying, supercritical fluid technology, electrospinning, KinetiSol, etc., have been devised to improve either or both the solubility and dissolution to enhance the bioavailability of these active substances belonging to BCS Class II and IV. The principle involved in all these preparation techniques is similar, where the crystal lattice of the drug is disrupted by either the application of heat or dissolving it in a solvent and the movement of the fine drug particles is arrested with the help of a polymer by either cooling or drying to remove the solvent. The dispersed drug particles in the polymer matrix have higher entropy and enthalpy and, thereby, higher free energy in comparison to the crystalline drug. Povidone, polymethaacrylate derivatives, hydroxypropyl methyl cellulose (HPMC) and hydroxypropyl methylcellulose acetate succinate derivatives are commonly used as polymers in the preparation of ASDs. Specifically, hydroxypropylmethylcellulose acetate succinate (HPMCAS)-based ASDs have become well established in commercially available products and are widely explored to improve the solubility of poorly soluble drugs. This article provides an analysis of two widely used manufacturing techniques for HPMCAS ASDs, namely, hot melt extrusion and spray drying. Additionally, details of HPMCAS-based ASD marketed products and patents have been discussed to emphasize the commercial aspect.

A Comparative Assessment of Cocrystal and Amorphous Solid Dispersion Printlets Developed by Hot Melt Extrusion Paired Fused Deposition Modeling for Dissolution Enhancement and Stability of Ibuprofen

The primary focus of the research is to study the role of cocrystal and amorphous solid dispersion approaches for enhancing solubility and preserving the stability of a poorly soluble drug, i.e., ibuprofen (IBP). First, the solvent-assisted grinding approach determined the optimum molar ratio of the drug and the coformer (nicotinamide (NIC)). Later, the polymeric filaments of cocrystals and amorphous solid dispersions were developed using the hot melt extrusion (HME) process, and the printlets were fabricated using the fused deposition modeling (FDM) additive manufacturing process. In addition, the obtained filaments were also milled and compressed into tablets as reference samples. The formation of cocrystals and amorphous solid dispersions was evaluated and confirmed using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and powder X-ray diffraction (PXRD) analysis. The drug release profiles of 3D printlets with 50% infill were found to be faster and are in line with the release profiles of compressed tablets. In addition, the 3D-printed cocrystal formulation was stable for 6 months at accelerated conditions. However, the 3D printlets of amorphous solid dispersions and compressed tablets failed to retain stability attributed to the recrystallization of the drug and loss in tablet mechanical properties. This shows the suitability of a cocrystal platform as a novel approach for developing stable formulations of poorly soluble drug substances over amorphous solid dispersions.

Emerging Applications of Hydroxypropyl Methylcellulose Acetate Succinate: Different Aspects in Drug Delivery and Its Commercial Potential

Hydroxypropyl methylcellulose acetate succinate (HPMCAS) has multi-disciplinary applications spanning across the development of drug delivery systems, in 3D printing, and in tissue engineering, etc. HPMCAS helps in maintaining the drug in a super-saturated condition by inhibiting its precipitation, thereby increasing the rate and extent of dissolution in the aqueous media. HPMCAS has several distinctive characteristics, such as being amphiphilic in nature, having an ionization pH, and a succinyl and acetyl substitution ratio, all of which are beneficial while developing formulations. This review provides insights regarding the various types of formulations being developed using HPMCAS, including amorphous solid dispersion (ASD), amorphous nanoparticles, dry coating, and 3D printing, along with their applicability in drug delivery and biomedical fields. Furthermore, HPMCAS, compared with other carbohydrate polymers, shows several benefits in drug delivery, including proficiency in imparting stable ASD with a high dissolution rate, being easily processable, and enhancing bioavailability. The various commercially available formulations, regulatory considerations, and key patents containing the HPMCAS have been discussed in this review.

Development of Delayed Release Oral Formulation Comprising Esomeprazole Spray Dried Dispersion Utilizing Design of Experiment As An Optimization Strategy

Solid dispersion (SD) technology is one of the most widely preferred solubility enhancement methods, especially for Biopharmaceutics classification system class II and IV drugs. Since the last decade, its application for the dual purpose of solubility hike and modified release using novel carriers has been in demand for its added advantages. Spray drying is a commercially accepted technique with high aspects of scalability and product characteristics. The current study used spray-dried dispersion to design delayed release capsule for the proton pump inhibitor esomeprazole. The SD carrier hydroxypropyl methylcellulose acetate succinate-medium grade (HPMCAS-MF) enhanced solubility, inhibited precipitation of saturated drug solutions, and allowed enteric release owing to its solubility above pH 6. The proposed approach avoided compression, coating with enteric polymers, and the development of multi-particulate pellet-based formulations, improving manufacturing feasibility. The formulation was optimized using Box-Behnken design, considering significant formulation variables like HPMCAS-MF proportion and critical process parameters like feed flow rate and inlet temperature. The optimized spray-dried dispersion were characterized based on Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM) and also evaluated for solubility, in vitro drug release, residual solvent content, and stability testing. Response surface methodology optimization anticipated that formulation variables affected solubility and release profile, whereas CPPs affected yield. The design space was developed via overlay plot based on constraints specified to attain the desired response and validated using three checkpoint batches with desirability 1. FTIR showed active pharmaceutical ingredient-polymer compatibility. Particle size and SEM studies showed spherical particles with an average Z-value of 1.8 µ. DSC and PXRD confirmed SD's amorphous nature. The drug release investigation and release kinetics prediction utilizing DD-solver software showed a 2-h lag time with > 90% cumulative drug release up to 4 h for the DR formulation. ESM SDD were prepared by spray drying technique using the novel solid dispersion carrier HPMCAS-MF to serve the dual purpose of solubility enhancement and delayed release. The ratio of API:carrier and process variables like feed flow rate and inlet temperature were varied using the Box-Behnken Design to determine the design space of optimized product to procure the desired characteristics of solubility improvement compared to crystalline API and delayed release of PPI to avoid the degradation in the gastric environment. The developed formulation represents several benefits over the already existing marketed products.

In-situ formation of nanoparticles from drug-loaded 3D polymeric matrices

The in-situ formation of nanoparticles from polymer-based solid medicines, although previously described, has been overlooked despite its potential to interfere with oral drug bioavailability. Such polymeric pharmaceuticals are becoming increasingly common on the market and can become even more popular due to the dizzying advance of 3D printing medicines. Hence, this work aimed to study this phenomenon during the dissolution of 3D printed tablets produced with three different polymers, hydroxypropylmethylcellulose acetate succinate (HPMCAS), polyvinyl alcohol (PVA), and Eudragit RL PO® (EUD RL) combined with plasticizers and the model drug naringenin (NAR). The components' interaction, dissolution behavior, and characteristics of the formed particles were investigated employing thermal, spectroscopic, mechanical, and chromatographic assays. All the systems generated stable spherical-shaped particles throughout 24 h, encapsulating over 25% of NAR. Results suggest encapsulation efficiencies variations may depend on interactions between polymer-drug, drug-plasticizer, and polymer-plasticizer, which formed stable nanoparticles even in the drug absence, as observed with the HPMCAS and EUD RL formulations. Additionally, components solubility in the medium and previous formulation treatments are also a decisive factor for nanoparticle formation. In particular, the treatment provided by hot-melt extrusion and FDM 3D printing affected the dissolution efficiency enhancing the interaction between the components, reverberating on particle size and particle formation kinetics mainly for HPMCAS and EUD RL. In conclusion, the 3D printing process influences the in-situ formation of nanoparticles, which can directly affect oral drug bioavailability and needs to be monitored.

Review of industrially recognized polymers and manufacturing processes for amorphous solid dispersion based formulations

Evolving therapeutic landscape through combinatorial chemistry and high throughput screening have resulted in an increased number of poorly soluble drugs. Drug delivery strategies quickly adapted to convert these drugs into successful therapies. Amorphous solid dispersion (ASD) technology is widely employed as a drug delivery strategy by pharmaceutical industries to overcome the challenges associated with these poorly soluble drugs. The development of ASD formulation requires an understanding of polymers and manufacturing techniques. A review of US FDA-approved ASD-based products revealed that only a limited number of polymers and manufacturing technologies are employed by pharmaceutical industries. This review provides a comprehensive guide for the selection and overview of polymers and manufacturing technologies adopted by pharmaceutical industries for ASD formulation. The various employed polymers with their underlying mechanisms for solution-state and solid-state stability are discussed. ASD manufacturing techniques, primarily implemented by pharmaceutical industries for commercialization, are presented in Quality by Design (QbD) format. An overview of novel excipients and progress in manufacturing technologies are also discussed. This review provides insights to the researchers on the industrially accepted polymers and manufacturing technology for ASD formulation that has translated these challenging drugs into successful therapies.

Molecular Dynamics Simulations of Selected Amorphous Stilbenoids and Their Amorphous Solid Dispersions with Poly(Vinylpyrrolidone)

Amorphous solid dispersions (ASDs) are one of the promising strategies to improve the solubility and dissolution rate of poorly soluble compounds. In this study, Molecular Dynamics simulations were used to investigate the interactions between three selected stilbenoids with important biological activity (resveratrol, pinostilbene and pterostilbene) and poly(vinylpyrrolidone). The analysis of the pair distribution functions and hydrogen bond distributions reveals a significant weakening of the hydrogen bond network of the stilbenoids in ASDs compared to the pure (no polymer) amorphous systems. This is accompanied by an increase in the mobility of the stilbenoid molecules in the ASDs, both in the translational dynamics determined from the molecular mean square displacements, and in the molecular reorientations followed by analysing several torsional distributions.

Impact of Poloxamer on Crystal Nucleation and Growth of Amorphous Clotrimazole

Surfactants have been widely used as effective additives to increase the solubility and dissolution rates of amorphous solid dispersions (ASDs). However, they may also generate adverse effects on the physical stability of ASDs. In this study, we systematically investigated the impacts of poloxamer, a frequently used surfactant, on the crystallization of amorphous clotrimazole (CMZ). The added poloxamer significantly decreased the glass transition temperature (Tg) of CMZ and accelerated the growth of Form 1 and Form 2 crystals. It was found that the poloxamer had an accelerating effect on Form 1 and Form 2 but showed a larger accelerating effect on Form 1, which resulted from a combined effect of increased mobility and local phase separation at the crystal-liquid interface. Additionally, the added poloxamer exhibited different effects on nucleation of the CMZ polymorphs, which was more complicated than crystal growth. The nucleation rate of Form 1 was significantly increased by the added poloxamer, and the effect increased with increasing P407 content. However, for Form 2, nucleation was slightly decreased or unchanged. The nucleation of Form 2 may have been influenced by the Form 1 crystallization, and Form 2 converted to Form 1 during nucleation. This study increases our understanding of poloxamer and its impacts on the melt crystallization of drugs.

Amorphous Solid Dispersion as Drug Delivery Vehicles in Cancer

Cancer treatment has improved over the past decades, but a major challenge lies in drug formulation, specifically for oral administration. Most anticancer drugs have poor water solubility which can affect their bioavailability. This causes suboptimal pharmacokinetic performance, resulting in limited efficacy and safety when administered orally. As a result, it is essential to develop a strategy to modify the solubility of anticancer drugs in oral formulations to improve their efficacy and safety. A promising approach that can be implemented is amorphous solid dispersion (ASD) which can enhance the aqueous solubility and bioavailability of poorly water-soluble drugs. The addition of a polymer can cause stability in the formulations and maintain a high supersaturation in bulk medium. Therefore, this study aimed to summarize and elucidate the mechanisms and impact of an amorphous solid dispersion system on cancer therapy. To gather relevant information, a comprehensive search was conducted using keywords such as "anticancer drug" and "amorphous solid dispersion" in the PubMed, Scopus, and Google Scholar databases. The review provides an overview and discussion of the issues related to the ASD system used to improve the bioavailability of anticancer drugs based on molecular pharmaceutics. A thorough understanding of anticancer drugs in this system at a molecular level is imperative for the rational design of the products.

Ternary Solid Dispersions: A Review of the Preparation, Characterization, Mechanism of Drug Release, and Physical Stability

The prevalence of active pharmaceutical ingredients (APIs) with low water solubility has experienced a significant increase in recent years. These APIs present challenges in formulation, particularly for oral dosage forms, despite their considerable therapeutic potential. Therefore, the improvement of solubility has become a major concern for pharmaceutical enterprises to increase the bioavailability of APIs. A promising formulation approach that can effectively improve the dissolution profile and the bioavailability of poorly water-soluble drugs is the utilization of amorphous systems. Numerous formulation methods have been developed to enhance poorly water-soluble drugs through amorphization systems, including co-amorphous formulations, amorphous solid dispersions (ASDs), and the use of mesoporous silica as a carrier. Furthermore, the successful enhancement of certain drugs with poor aqueous solubility through amorphization has led to their incorporation into various commercially available preparations, such as ASDs, where the crystalline structure of APIs is transformed into an amorphous state within a hydrophilic matrix. A novel approach, known as ternary solid dispersions (TSDs), has emerged to address the solubility and bioavailability challenges associated with amorphous drugs. Meanwhile, the introduction of a third component in the ASD and co-amorphous systems has demonstrated the potential to improve performance in terms of solubility, physical stability, and processability. This comprehensive review discusses the preparation and characterization of poorly water-soluble drugs in ternary solid dispersions and their mechanisms of drug release and physical stability.

Enhanced Oral Bioavailability of Rivaroxaban-Loaded Microspheres by Optimizing the Polymer and Surfactant Based on Molecular Interaction Mechanisms

This study aimed to develop microspheres using water-soluble carriers and surfactants to improve the solubility, dissolution, and oral bioavailability of rivaroxaban (RXB). RXB-loaded microspheres with optimal carrier (poly(vinylpyrrolidone) K30, PVP) and surfactant (sodium lauryl sulfate (SLS)) ratios were prepared. 1H NMR and Fourier transform infrared (FTIR) analyses showed that drug-excipient and excipient-excipient interactions affected RXB solubility, dissolution, and oral absorption. Therefore, molecular interactions between RXB, PVP, and SLS played an important role in improving RXB solubility, dissolution, and oral bioavailability. Formulations IV and VIII, containing optimized RXB/PVP/SLS ratios (1:0.25:2 and 1:1:2, w/w/w), had significantly improved solubility by approximately 160- and 86-fold, respectively, compared to RXB powder, with the final dissolution rates improved by approximately 4.5- and 3.4-fold, respectively, compared to those of RXB powder at 120 min. Moreover, the oral bioavailability of RXB was improved by 2.4- and 1.7-fold, respectively, compared to that of RXB powder. Formulation IV showed the highest improvement in oral bioavailability compared to RXB powder (AUC, 2400.8 ± 237.1 vs 1002.0 ± 82.3 h·ng/mL). Finally, the microspheres developed in this study successfully improved the solubility, dissolution rate, and bioavailability of RXB, suggesting that formulation optimization with the optimal drug-to-excipient ratio can lead to successful formulation development.

Formulation of New Chewable Oral Dosage Forms of Meclizine and Pyridoxine Hydrochloride

Nausea and vomiting are symptoms associated with a lot of diseases and oral tablets may be unprofitable for patients especially those suffering from nausea and vomiting. Therefore, this study aimed to formulate a new meclizine and pyridoxine combination formula for chewable tablets and provide rapid drug absorption and decrease motion sickness. The new chewable formulation has been prepared to provide fast action, is more acceptable, and could be used for all age categories. Seven trials haves been carried out to prepare to find the suitable one where formula 7 of the chewable gum preparation exhibited good taste and hardness, while the gelatin formulation give an accepted formula after four trials with better taste and good acceptance. The prepared formulations give a dissolution profile of meclizine (95.53-102.8%) and pyridoxine (99.25 ± 115%) and assay (98 + 0.05-99.3 ± 0.8%) for meclizine and (97 ± 0.9-100.0 ± 0.08%) for the pyridoxine in three prepared formulations of chewable tablets. Followed by the evaluation, the formulation and testing them on human volunteers are carried out to confirm their effect to ensure acceptance and fast actions. The finding is promising for preparing a new route of administration of meclizine and pyridoxine combination to be used in the market.

Dissolution-permeation of hot-melt extruded amorphous solid dispersion comprising an experimental grade of HPMCAS

Background and purpose

Physicochemical properties of an amorphous solid dispersion (ASD) comprising an experimental grade of hydroxypropyl methylcellulose acetate succinate (HPMCAS-MX) with lower glass transition temperature have been previously investigated. This study aimed to evaluate applicability of HPMCAS-MX to hot-melt extrusion (HME) and dissolution-permeation performance of prepared ASDs using MicroFLUX.

Review approach

A physical mixture of indomethacin (IMC) and HPMCAS-MX or -MG (a commercial grade with higher transition temperature) at 20:80 weight ratio was hot-melt extruded to prepare an ASD (IMC-MX and IMC-MG, respectively). The dissolution-permeation performance and the stability of the ASDs were measured.

Key results

A torque reduction at 120 °C implied that IMC-MX transformed into an amorphous state at this temperature, but IMC-MG required around 170 °C. This result was supported by Raman mapping of the the HME samples. IMC-MG and IMC-MX remained in an amorphous state at 40 °C for three months. The initial dissolution rate and solubility of the ASDs were higher than that of crystalline IMC. The apparent permeability of IMC from IMC-MX and IMC-MG was comparable but was approximately two-fold higher than that from crystalline IMC.

Conclusion

HPMCAS-MX enabled HME process at a lower temperature and improved the dissolution-permeation performance of indomethacin.

Development of Lipid Polymer Hybrid Drug Delivery Systems Prepared by Hot-Melt Extrusion

This study sought to develop polymer-lipid hybrid solid dispersions containing the poorly soluble drug lopinavir (LPV) by hot-melt extrusion (HME). Hence, the lipid and polymeric adjuvants were selected based on miscibility and compatibility studies. Film casting was used to assess the miscibility, whereas thermal, spectroscopic, and chromatographic analyses were employed to evaluate drug-excipient compatibility. Extrudates were obtained and characterized by physicochemical tests, including in vitro LPV dissolution. Preformulation studies led to select the most appropriate materials, i.e., the polymers PVPVA and Soluplus®, the plasticizers polyethylene glycol 400 and Kolliphor® HS15, phosphatidylcholine, and sodium taurodeoxycholate. HME processing did not result in LPV degradation and significantly increased entrapment efficiency (93.8% ± 2.8 for Soluplus® extrudate against 19.8% ± 0.5 of the respective physical mixture). LPV dissolution was also increased from the extrudates compared to the corresponding physical mixtures (p < 0.05). The dissolution improvement was considerably greater for the Soluplus®-based formulation (24.3 and 2.8-fold higher than pure LPV and PVPVA-based extrudate after 120 min, respectively), which can be attributed to the more pronounced effects of HME processing on the average size and LPV solid-state properties in the Soluplus® extrudates. Transmission electron microscopy and chemical microanalysis suggested that the polymer-lipid interactions in Soluplus®-based formulation depended on thermal processing.

Effect of Drug-Polymer Interaction in Amorphous Solid Dispersion on the Physical Stability and Dissolution of Drugs: The Case of Alpha-Mangostin

Improving drug solubility is necessary for formulations of poorly water-soluble drugs, especially for oral administration. Amorphous solid dispersions (ASDs) are widely used in the pharmaceutical industry to improve the physical stability and solubility of drugs. Therefore, this study aims to characterize interaction between a drug and polymer in ASD, as well as evaluate the impact on the physical stability and dissolution of alpha-mangostin (AM). AM was used as a model of a poorly water-soluble drug, while polyvinylpyrrolidone (PVP) and eudragit were used as polymers. The amorphization of AM-eudragit and AM-PVP was confirmed as having a halo pattern with powder X-ray diffraction measurements and the absence of an AM melting peak in the differential scanning calorimetry (DSC) curve. The solubility of amorphous AM increased in the presence of either eudragit or PVP due to amorphization and interactions of AM-polymer. Furthermore, FT-IR spectroscopy and in silico studies revealed hydrogen bond interactions between the carbonyl group of AM and the proton of eudragit as well as PVP. AM-eudragit with a ratio of 1:1 recrystallized after 7 days of storage at 25 °C and 90% RH, while the AM-PVP 1:4 and 1:10 samples retained the X-ray halo patterns, even under humid conditions. In a dissolution test, the presence of polymer in ASD significantly improved the dissolution profile due to the intermolecular interaction of AM-polymer. AM-eudragit 1:4 maintained AM supersaturation for a longer time compared to the 1:1 sample. However, a high supersaturation was not achieved in AM-PVP 1:10 due to the formation of large agglomerations, leading to a slow dissolution rate. Based on the results, interaction of AM-polymer in ASD can significantly improve the pharmaceutical properties of AM including the physical stability and dissolution.

Multiscale X-ray imaging and characterisation of pharmaceutical dosage forms

A correlative, multiscale imaging methodology for visualising and quantifying the morphology of solid dosage forms by combining ptychographic X-ray computed nanotomography (PXCT) and scanning small- and wide-angle X-ray scattering (S/WAXS) is presented. The methodology presents a workflow for multiscale analysis, where structures are characterised from the nanometre to millimetre regime. Here, the method is demonstrated by characterising a hot-melt extruded, partly crystalline, solid dispersion of carbamazepine in ethyl cellulose. Characterisation of the morphology and solid-state phase of the drug in solid dosage forms is central as this affects the performance of the final formulation. The 3D morphology was visualised at a resolution of 80 nm over an extended volume through PXCT, revealing an oriented structure of crystalline drug domains aligned in the direction of extrusion. Scanning S/WAXS, showed that the nanostructure is similar over the cross section of the extruded filament, with minor radial changes in domain sizes and degree of orientation. The polymorphic forms of carbamazepine were qualified with WAXS, showing a heterogeneous distribution of the metastable forms I and II. This demonstrates the methodology for multiscale structural characterization and imaging to enable a better understanding of the relationships between morphology, performance, and processing conditions of solid dosage forms.

Advances in the development of amorphous solid dispersions: The role of polymeric carriers

Amorphous solid dispersion (ASD) is one of the most effective approaches for delivering poorly soluble drugs. In ASDs, polymeric materials serve as the carriers in which the drugs are dispersed at the molecular level. To prepare the solid dispersions, there are many polymers with various physicochemical and thermochemical characteristics available for use in ASD formulations. Polymer selection is of great importance because it influences the stability, solubility and dissolution rates, manufacturing process, and bioavailability of the ASD. This review article provides a comprehensive overview of ASDs from the perspectives of physicochemical characteristics of polymers, formulation designs and preparation methods. Furthermore, considerations of safety and regulatory requirements along with the studies recommended for characterizing and evaluating polymeric carriers are briefly discussed.

The Use of Hot Melt Extrusion to Prepare a Solid Dispersion of Ibuprofen in a Polymer Matrix

In this work, we report the use of the hot melt extrusion method in harsh extrusion conditions, i.e., screw rotation speed of 250 rpm, temperature above 100 °C, and two mixing zones, in order to obtain an amorphous dispersion of an active pharmaceutical ingredient (API) that is sparingly soluble in water. As a polymer matrix Eudragit EPO (E-EPO) and as an API ibuprofen (IBU) were used in the research. In addition, the plasticizer Compritol 888 ATO (COM) was tested as a factor potentially improving processing parameters and modifying the IBU release profile. In studies, 25% by weight of IBU, 10% of COM and various extrusion temperatures, i.e., 90, 100, 120, 130, and 140 °C, were used. Hot melt extrusion (HME) temperatures were selected based on the glass transition temperature of the polymer matrix (T_g = 42 °C) and the melting points of IBU (T_m = 76 °C) and COM (T_m = 73 °C), which were tested by differential scanning calorimetry (DSC). The thermal stability of the tested compounds, determined on the basis of measurements carried out by thermogravimetric analysis (TGA), was also taken into account. HME resulted in amorphous E-EPO/IBU solid dispersions and solid dispersions containing a partially crystalline plasticizer in the case of E-EPO/IBU/COM extrudates. Interactions between the components of the extrudate were also studied using infrared spectroscopy (FTIR-ATR). The occurrence of such interactions in the studied system, which improve the stability of the obtained solid polymer dispersions, was confirmed. On the basis of DSC thermograms and XRPD diffractograms, it was found that amorphous solid dispersions were obtained. In addition, their stability was confirmed in accelerated conditions (40 °C, 75% RH) for 28 days and 3 months. The release profiles of prepared tablets showed the release of 40% to 63% of IBU from the tablets within 180 min in artificial gastric juice solution, with the best results obtained for tablets with E-EPO/IBU extrudate prepared at a processing temperature of 140 °C.

Biological Activities and Solubilization Methodologies of Naringin

Naringin (NG), a natural flavanone glycoside, possesses a multitude of pharmacological properties, encompassing anti-inflammatory, sedative, antioxidant, anticancer, anti-osteoporosis, and lipid-lowering functions, and serves as a facilitator for the absorption of other drugs. Despite these powerful qualities, NG's limited solubility and bioavailability primarily undermine its therapeutic potential. Consequently, innovative solubilization methodologies have received considerable attention, propelling a surge of scholarly investigation in this arena. Among the most promising solutions is the enhancement of NG's solubility and physiological activity without compromising its inherent active structure, therefore enabling the formulation of non-toxic and benign human body preparations. This article delivers a comprehensive overview of NG and its physiological activities, particularly emphasizing the impacts of structural modification, solid dispersions (SDs), inclusion compound, polymeric micelle, liposomes, and nanoparticles on NG solubilization. By synthesizing current research, this research elucidates the bioavailability of NG, broadens its clinical applicability, and paves the way for further exploration and expansion of its application spectrum.

Drug complexes: Perspective from Academic Research and Pharmaceutical Market

Despite numerous research efforts, drug delivery through the oral route remains a major challenge to formulation scientists. The oral delivery of drugs poses a significant challenge because more than 40% of new chemical entities are practically insoluble in water. Low aqueous solubility is the main problem encountered during the formulation development of new actives and for generic development. A complexation approach has been widely investigated to address this issue, which subsequently improves the bioavailability of these drugs. This review discusses the various types of complexes such as metal complex (drug-metal ion), organic molecules (drug-caffeine or drug-hydrophilic polymer), inclusion complex (drug-cyclodextrin), and pharmacosomes (drug-phospholipids) that improves the aqueous solubility, dissolution, and permeability of the drug along with the numerous case studies reported in the literature. Besides improving solubility, drug-complexation provides versatile functions like improving stability, reducing the toxicity of drugs, increasing or decreasing the dissolution rate, and enhancing bioavailability and biodistribution. Apart, various methods to predict the stoichiometric ratio of reactants and the stability of the developed complex are discussed.

Bulk Flow Optimisation of Amorphous Solid Dispersion Excipient Powders through Surface Modification

Particulate amorphous solid dispersions (ASDs) have been recognised for their potential to enhance the performance of various solid dose forms, especially oral bioavailability and macromolecule stability. However, the inherent nature of spray-dried ASDs leads to their surface cohesion/adhesion, including hygroscopicity, which hinders their bulk flow and affects their utility and viability in terms of powder production, processing, and function. This study explores the effectiveness of L-leucine (L-leu) coprocessing in modifying the particle surface of ASD-forming materials. Various contrasting prototype coprocessed ASD excipients from both the food and pharmaceutical industries were examined for their effective coformulation with L-leu. The model/prototype materials included maltodextrin, polyvinylpyrrolidone (PVP K10 and K90), trehalose, gum arabic, and hydroxypropyl methylcellulose (HPMC E5LV and K100M). The spray-drying conditions were set such that the particle size difference was minimised, so that it did not play a substantial role in influencing powder cohesion. Scanning electron microscopy was used to evaluate the morphology of each formulation. A combination of previously reported morphological progression typical of L-leu surface modification and previously unreported physical characteristics was observed. The bulk characteristics of these powders were assessed using a powder rheometer to evaluate their flowability under confined and unconfined stresses, flow rate sensitivities, and compactability. The data showed a general improvement in maltodextrin, PVP K10, trehalose and gum arabic flowability measures as L-leu concentrations increased. In contrast, PVP K90 and HPMC formulations experienced unique challenges that provided insight into the mechanistic behaviour of L-leu. Therefore, this study recommends further investigations into the interplay between L-leu and the physico-chemical properties of coformulated excipients in future amorphous powder design. This also revealed the need to enhance bulk characterisation tools to unpack the multifactorial impact of L-leu surface modification.

Kinetic Stability and Glass-Forming Ability of Thermally Labile Quinolone Antibiotics

The application of drugs in the amorphous state is one way to improve their bioavailability. As such, the determination of the optimal conditions for production and the assessment of the stability of the amorphous system are actively researched topics of present-day pharmaceutical science. In the present work, we have studied the kinetic stability and glass-forming ability of the thermally labile quinolone antibiotics using fast scanning calorimetry. The critical cooling rates for avoiding crystallization of the melts of oxolinic and pipemidic acids and sparfloxacin were determined to be 10 000, 40, and 80 K·s^-1, respectively. The studied antibiotics were found to be "strong" glass formers. Based on a combination of nonisothermal and isothermal kinetic approaches, the Nakamura model was suitable for describing the crystallization process of the amorphous forms of the quinolone antibiotics.

In vitro-in vivo relationship for amorphous solid dispersions using a double membrane dissolution-permeation setup

The use of amorphous solid dispersions (ASDs) is one commonly applied formulation strategy to improve the oral bioavailability of poorly water-soluble drugs by overcoming dissolution rate and/or solubility limitations. While bioavailability enhancement of ASDs is well documented, it has often been a challenge to establish a predictive model describing in vitro-in vivo relationship (IVIVR). In this study, it is hypothesized that drug absorption might be overestimated by in vitro dissolution-permeation (D/P)-setups, when drug in suspension has the possibility of directly interacting with the permeation barrier. This is supported by the overprediction of drug absorption from neat crystalline efavirenz compared to four ASDs in a D/P-setup based on the parallel artificial membrane permeability assay (PAMPA). However, linear IVIVR (R² = 0.97) is established in a modified D/P-setup in which the addition of a hydrophilic PVDF-filter acts as a physical boundary between the donor compartment and the PAMPA-membrane. Based on microscopic visualization, the improved predictability of the modified D/P-setup is due to the avoidance of direct dissolution of drug particles in the lipid components of the PAMPA-membrane. In general, this principle might aid in providing a more reliable evaluation of formulations of poorly water-soluble drugs before initiating animal models.

Hard Gelatin Capsules Containing Hot Melt Extruded Solid Crystal Suspension of Carbamazepine for improving dissolution: Preparation and In vitro Evaluation

Aqueous solubility is one of the key parameters for achieving the desired drug concentration in systemic circulation for better therapeutic outcomes. Carbamazepine (CBZ) is practically insoluble in water, is a BCS class II drug, and exhibits dissolution-dependent oral bioavailability. This study explored a novel application of hot-melt extrusion in the manufacture and development of a thermodynamically stable solid crystal suspension (SCS) to improve the solubility and dissolution rate of CBZ. The SCSs were prepared using sugar alcohols, such as mannitol or xylitol, as crystalline carriers. The drug-sugar blend was processed by hot melt extrusion up to 40 % (w/w) drug loading. The extruded SCS was evaluated for drug content, saturation solubility, differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, powder X-ray diffraction (PXRD), scanning electron microscopy (SEM), in vitro release, and stability studies. The physicochemical characterization revealed the highly crystalline existence of pure drug, pure carriers, and extruded SCS. FTIR analysis did not reveal any physical or chemical incompatibilities between the drug and sugar alcohols and showed a homogeneous CBZ distribution within respective crystalline carriers. The SEM micrographs of the solidified SCS revealed the presence of approximately 100 μm crystalline agglomerates. In vitro dissolution and solubility studies showed that the CBZ dissolution rate and solubility were improved significantly from both crystalline carriers for all tested drug loads. The SCSs showed no significant changes in drug content, in vitro release profiles, and thermal characteristics over 3 months of storage at accelerated stability conditions (40±2°C/75±5% RH). As a result, it can be inferred that the SCS strategy can be employed as a contemporary alternative technique to improve the dissolution rate of BCS class II drugs via HME technology.