Evaluation of the Solid Dispersion System Engineered from Mesoporous Silica and Polymers for the Poorly Water Soluble Drug Indomethacin: In Vitro and In Vivo

Development, Characterization, and Cellular Toxicity Evaluation of Solid Dispersion-Loaded Hydrogel Based on Indomethacin

Indomethacin (IND) as a non-selective cyclooxygenase 1 and 2 inhibitor administered orally causes numerous adverse effects, mostly related to the gastrointestinal tract. Moreover, when applied exogenously in topical preparations, there are obstacles to its permeation through the stratum corneum due to its low water solubility and susceptibility to photodegradation. In this work, solid dispersions (SDs) of IND with low-substituted hydroxypropyl cellulose (LHPC) were developed. The IND-SDs were incorporated into a hydroxypropyl guar (HPG) hydrogel to enhance drug solubility on the skin. The hydrogels were characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), powder X-ray diffraction (XRPD), Fourier-transform infrared spectroscopy (FTIR), viscosity, drug release, and unspecific cytotoxicity in mammalian cells. SEM showed a highly porous structure for SD hydrogels. DSC and XRPD studies showed that amorphous IND species were formed; therefore, these hydrogels exhibited superior drug release in comparison with IND raw material hydrogels. FTIR evidenced the presence of the hydrogen bond in the SD hydrogel. The rheology parameter viscosity increased across gels formulated with SDs in comparison with hydrogels with pure IND. In addition, IND-SD hydrogels combine the advantages of a suitable viscosity for dermal use and no potentially hazardous skin irritation. This study suggests that the formulated IND-SD hydrogels represent a suitable candidate for topical administration.

Modification of microenvironmental pH of nanoparticles for enhanced solubility and oral bioavailability of poorly water-soluble celecoxib

This study aimed to develop a novel pH-modified nanoparticle with improved solubility and oral bioavailability of poorly water-soluble celecoxib by modifying the microenvironmental pH. After assessing the impact of hydrophilic polymers, surfactants and alkaline pH modifiers on the drug solubility, copovidone, sodium lauryl sulfate (SLS) and meglumine were chosen. The optimal formulation of solvent-evaporated, surface-attached and pH-modified nanoparticles composed of celecoxib/copovidone/SLS/meglumine at weight ratios of 1:1:0.2:0, 1:0.375:1.125:0 and 1:1:1:0.2:0.02, respectively, were manufactured using spray drying technique. Their physicochemical characteristics, solubility, dissolution and pharmacokinetics in rats were evaluated compared to the celecoxib powder. The solvent-evaporated and pH-modified nanoparticles converted a crystalline to an amorphous drug, resulting in a spherical shape with a reduced particle size compared to celecoxib powder. However, the surface-attached nanoparticles with insignificant particle size exhibited the unchangeable crystalline drug. All of them gave significantly higher solubility, dissolution, and oral bioavailability than celecoxib powder. Among them, the pH-modified nanoparticles demonstrated the most significant improvement in solubility (approximately 1600-fold) and oral bioavailability (approximately 4-fold) compared to the drug powder owing to the alkaline microenvironment formation effect of meglumine and the conversion to the amorphous drug. Thus, the pH-modified nanoparticle system would be a promising strategy for improving the solubility and oral bioavailability of poorly water-soluble and weakly acidic celecoxib.

The Fabrication, Drug Loading, and Release Behavior of Porous Mannitol

Porous materials are widely used as an effective strategy for the solubilization of insoluble drugs. In order to improve the solubility and bioavailability of low water-solubility drugs, it is necessary to prepare porous materials. Mannitol is one of the most popular excipients in food and drug formulations. In this study, porous mannitol was investigated as a drug carrier for low water solubility drugs. Its fabrication, drug loading, and drug release mechanisms were investigated. Porous mannitol was fabricated using the co-spray-antisolvent process and utilizing polyvinylpyrrolidone K30 (PVP K30) as the template agent. Porous mannitol particles were prepared by changing the proportion of the template agent, spraying the particles with mannitol, and eluting with ethanol in order to regulate their pore structure. In subsequent studies, porous mannitol morphology and characteristics were determined systematically. Furthermore, curcumin and ibuprofen, two poorly water-soluble drugs, were loaded into porous mannitol, and their release profiles were analyzed. The results of the study indicated that porous mannitol can be prepared using PVP K30 as a template and that the amount of template agent can be adjusted in order to control the structure of the porous mannitol. When the template agent was added in amounts of 1%, 3%, and 5%, the mannitol pore size increased by 167.80%, 95.16%, and 163.98%, respectively, compared to raw mannitol. Molecular docking revealed that mannitol and drugs are adsorbents and adhere to each other by force interaction. The cumulative dissolution of curcumin and ibuprofen-loaded porous mannitol reached 69% and 70%, respectively. The release mechanism of curcumin and ibuprofen from drug-loaded mannitol was suitable for the Korsmeyer-Peppas kinetic model. In summary, the co-spray-antisolvent method proved effective in fabricating porous materials rapidly, and porous mannitol had a remarkable effect on drug solubilization. The results obtained are conducive to the development of porous materials.

Mesoporous Drug Delivery System: From Physical Properties of Drug in Solid State to Controlled Release

Mesoporous materials, which exhibit great potential in the control of polymorphs and delivery of poorly water-soluble drugs, have obtained considerable attention in the field of pharmaceutical science. The physical properties and release behaviors of amorphous or crystalline drugs may be affected by formulating them into mesoporous drug delivery systems. In the past few decades, an increasing amount of papers have been written about mesoporous drug delivery systems, which play a crucial role in improving the properties of drugs. Herein, mesoporous drug delivery systems are comprehensively reviewed in terms of their physicochemical characteristics, control of polymorphic forms, physical stability, in vitro performance, and in vivo performance. Moreover, the challenges and strategies of developing robust mesoporous drug delivery systems are also discussed.

Key Parameters for the Rational Design, Synthesis, and Functionalization of Biocompatible Mesoporous Silica Nanoparticles

Over the last few years, research on silica nanoparticles has rapidly increased. Particularly on mesoporous silica nanoparticles (MSNs), as nanocarriers for the treatment of various diseases because of their physicochemical properties and biocompatibility. The use of MSNs combined with therapeutic agents can provide better encapsulation and effective delivery. MSNs as nanocarriers might also be a promising tool to lower the therapeutic dosage levels and thereby to reduce undesired side effects. Researchers have explored several routes to conjugate both imaging and therapeutic agents onto MSNs, thus expanding their potential as theranostic platforms, in order to allow for the early diagnosis and treatment of diseases. This review introduces a general overview of recent advances in the field of silica nanoparticles. In particular, the review tackles the fundamental aspects of silicate materials, including a historical presentation to new silicates and then focusing on the key parameters that govern the tailored synthesis of functional MSNs. Finally, the biomedical applications of MSNs are briefly revised, along with their biocompatibility, biodistribution and degradation. This review aims to provide the reader with the tools for a rational design of biocompatible MSNs for their application in the biomedical field. Particular attention is paid to the role that the synthesis conditions have on the physicochemical properties of the resulting MSNs, which, in turn, will determine their pharmacological behavior. Several recent examples are highlighted to stress the potential that MSNs hold as drug delivery systems, for biomedical imaging, as vaccine adjuvants and as theragnostic agents.

Gastroretentive Sustained-Release Tablets Combined with a Solid Self-Micro-Emulsifying Drug Delivery System Adsorbed onto Fujicalin®

Gastroretentive drug delivery systems (GRDDS) get retained in the stomach for a long time, thus facilitating the absorption of drugs in the upper gastrointestinal tract. However, drugs that are difficult to dissolve or unstable in an acidic environment are not suitable for GRDDS. The current study designs GRDDS combined with a self-micro-emulsifying drug delivery system (SMEDDS) for drugs with solubility or stability problems in the stomach. The model drug fenofibrate was formulated into the optimized liquid SMEDDS composed of 50 w/w% Capryol^® PGMC, 40 w/w% Kolliphor^® RH40, and 10 w/w% Transcutol^® HP and solidified through adsorption on several porous adsorbents. In a dissolution medium at pH 1.2, the powdered SMEDDS using Fujicalin^® dissolved quickly and achieved higher drug dissolution than other adsorbents. Based on these results, a gastroretentive bilayer tablet consisting of a drug release layer and a swelling layer was designed. The drug release layer was formulated with the powdered SMEDDS and hydroxypropyl methylcellulose (HPMC) as a release modifier. HPMC was also added to the swelling layer as a water-swellable polymer. The dissolution rate depended on the viscosity of the HPMC in the drug release layer. The time for 90% drug release was extended from 3.7 to 12.0 h by increasing the viscosity grade of HPMC from 0.1 to 100 K. Moreover, the tablet swelled and maintained a size comparable to a human pylorus diameter or more for at least 24 h. This GRDDS could apply to a broader range of drug candidates.

Amorphous Solid Dispersions (ASDs): The Influence of Material Properties, Manufacturing Processes and Analytical Technologies in Drug Product Development

Poorly water-soluble drugs pose a significant challenge to developability due to poor oral absorption leading to poor bioavailability. Several approaches exist that improve the oral absorption of such compounds by enhancing the aqueous solubility and/or dissolution rate of the drug. These include chemical modifications such as salts, co-crystals or prodrugs and physical modifications such as complexation, nanocrystals or conversion to amorphous form. Among these formulation strategies, the conversion to amorphous form has been successfully deployed across the pharmaceutical industry, accounting for approximately 30% of the marketed products that require solubility enhancement and making it the most frequently used technology from 2000 to 2020. This article discusses the underlying scientific theory and influence of the active compound, the material properties and manufacturing processes on the selection and design of amorphous solid dispersion (ASD) products as marketed products. Recent advances in the analytical tools to characterize ASDs stability and ability to be processed into suitable, patient-centric dosage forms are also described. The unmet need and regulatory path for the development of novel ASD polymers is finally discussed, including a description of the experimental data that can be used to establish if a new polymer offers sufficient differentiation from the established polymers to warrant advancement.

Insights into the ameliorating ability of mesoporous silica in modulating drug release in ternary amorphous solid dispersion prepared by hot melt extrusion

In this work, the application of various mesoporous silica grades in the preparation of stabilized ternary amorphous solid dispersions of Felodipine using hot melt extrusion was explored. We have demonstrated the effectiveness of mesoporous silica in these dispersions without the need for any organic solvents i.e., no pre-loading or immersion steps required. The physical and chemical properties, release profiles of the prepared formulations and the surface concentrations of the various molecular species were investigated in detail. Formulations containing 25 wt% and 50 wt% of Felodipine demonstrated enhanced stability and solubility of the drug substance compared to its crystalline counterpart. Based on the Higuchi model, ternary formulations exhibited a 2-step or 3-step release pattern which can be ascribed to the release of drug molecules from the organic polymer matrix and the external silica surface, followed by a release from the silica pore structure. According to the Korsmeyer-Peppas model, the release rate and release mechanism are governed by a complex quasi-Fickian release mechanism, in which multiple release mechanisms are occurring concurrently and consequently. Stability studies indicated that after 6 months storage of all formulation at 30% RH and 20 °C, Felodipine in all formulations remained stable in its amorphous state except for the formulation comprised of 40 wt% Syloid AL-1FP with a 50 wt% drug load.

Synergistic application of twin-screw granulation and selective laser sintering 3D printing for the development of pharmaceutical dosage forms with enhanced dissolution rates and physical properties

This study demonstrated the first case of combining a novel continuous granulation technique with powder-bed fusion-based selective laser sintering (SLS) process to enhance the dissolution rate and physical properties of a poorly water-soluble drug. Selective laser sintering and binder jetting 3D printing processes have gained much attention in pharmaceutical dosage form manufacturing in recent times. These powder bed-based 3D printing platforms have been known to face printing and uniformity problems due to the inherent poor flow properties of the pharmaceutical physical mixtures. To address this issue a hot-melt extrusion-based versatile granulation process equipped with a process analytical technology (PAT) tool for the in-line monitoring of critical quality attributes (i.e., solid-state) of indomethacin was developed. The collected granules with enhanced flow properties were mixed with Kollidon® VA64 and a conductive excipient for efficient sintering. These mixtures were further characterized for their bulk properties observing an excellent flow and later subjected to an SLS-3D printing process. The physical mixtures, processed granules, and printed tablets were characterized using conventional as well as advanced solid-state characterizations. These characterizations revealed the amorphous nature of the drug in the processed granules and printed tablets. Further, the in vitro release testing of the tablets with produced granules as a reference standard depicted a notable dissolution advantage (100% drug released in 5 min at >pH 6.8) over the pure drug and the physical mixture. Our developed system known as DosePlus combines innovative continuous granulation and SLS-3D printing process which can potentially improve the physical properties of the bulk drug and formulations in comparison to when used in isolation. This process can further find application in continuous manufacturing of granules and additive manufacturing of pharmaceuticals to produce dosage forms with excellent uniformity and solubility advantage.

Ternary Amorphous Solid Dispersions Containing a High-Viscosity Polymer and Mesoporous Silica Enhance Dissolution Performance†

The aim of this study was to evaluate the benefits of a ternary amorphous solid dispersion (ASD) that was designed as an immediate-release tablet with a high drug load (e.g., 40% w/w) to produce heightened maintenance of drug supersaturation during dissolution testing, which will be henceforth referred to as the "maintenance ability". Ternary ASD granules were produced by hot melt extrusion (HME) and were comprised of itraconazole (ITZ) 50%, hypromellose (HPMC) 20%, and mesoporous silica (XDP) 30%, where amorphous ITZ incorporated into HPMC was efficiently absorbed in XDP pores. The ternary ASD granules containing a high-viscosity HPMC (AF4M) produced a significantly heightened maintenance ability of drug supersaturation in neutral pH dissolution media in which crystalline ITZ solubility is below 1 μg/mL. The final tablet formulation contained 80% w/w of the ASD granules (40% w/w ITZ), had an acceptable size, and exhibited both sufficient tablet hardness and disintegration. The dissolution behavior of the ternary ASD tablet exhibited a supersaturation maintenance ability similar to that of the ASD granules. Under neutral conditions, the ternary ASD tablet showed immediate and higher ITZ release compared with the binary ASD tablets, and this phenomenon could be explained by the difference in ITZ/AF4M particle size in the tablet. In high-resolution scanning electron microscopy (SEM), it was observed that ITZ and AF4M in the ternary formulation could easily form nano-sized particles (<1 μm) during the absorption process into/onto XDP pores prepared by HME, which contributed to the immediate ITZ release from the ternary ASD tablet under neutral pH conditions. Therefore, the ternary ASD containing high-viscosity HPMC and mesoporous silica prepared by HME made it possible to design a high ASD content, small-size tablet with an ideal dissolution profile in biorelevant media, and we expect that this technology can be applied for continuous HME ASD manufacturing.

Lamotrigine Nanoparticle Laden Polymer Composite Oral Dissolving Films for Improving Therapeutic Potential of the Hydrophobic Antiepileptic Molecule

Lamotrigine is used for neurological disorders and antiepileptic therapy at frequent dosing due to its poor solubility. The present work aims to study the influence of combining the Lamotrigine nanoparticles and polymer composite oral dissolving film to improve the solubility and dissolution kinetics of the drug. The Lamotrigine-Eudragit E100 nanoparticles were synthesized through solvent evaporation followed by precipitation process, which were laden in oral dissolving films through solvent casting technique. The optimized nanoparticles were assessed for particle size, colloidal stability, drug entrapment efficiency, in vitro release profile, physicochemical characteristics, and cytotoxicity. The optimized polymeric nanoparticles of Lamotrigine: Eudragit E100 (1:0.5) exhibited monodispersed particles with 103 nm average size, +7.96 mV zeta potential, and 82.96% ± 1.2% entrapment efficiency. The composite oral matrix films blended with polyvinyl alcohol and polyvinyl pyrrolidone (0.5:0.5 ratio) incorporated with the polymeric nanoparticles demonstrated >64% drug release within 2 h. The nanoparticles and its composite films exhibited 9- and 11-fold higher drug release than pure drug, respectively. The analytical characterization studies proved the formation of nanoparticles with mild drug-polymer interactions and optimum stability, which resulted in enhanced solubility and dissolution of drug. The nanoparticles displayed lesser cytotoxicity to the normal (Vero) cells at concentration of 10-50 μg/mL compared to pure drug. The optimized polymeric nanoparticle loaded oral films could be suitable for in vivo administration of Lamotrigine at low doses to improve bioavailability and therapeutic efficiency with reduced side effects.