Strategies to address low drug solubility in discovery and development

Deep eutectic solvents in analysis, delivery and chemistry of pharmaceuticals

Deep eutectic solvents (DES) have an emerging scientific role, assisting modern pharmaceutics. They are uniquely supporting the resolution of crucial issues, such as the effective extraction and isolation of bio-actives. They act as media and catalysts for pharmaceutical drug synthesis, and as green solvents and modifiers in pharmaceutical analysis. Their role in pharmaceutical formulation and drug delivery is also up-and-coming, for instance, as alternative drug-solubilizing agents, drug stabilizers and functional additives, as therapeutic deep eutectic solvents, deep eutectic API, and monomers and reaction media for the synthesis of biomaterials for advanced drug delivery. The DES also help transforming medicinal/pharmaceutical chemistry. Although DES were described in 1918, their first pharmaceutical use is only reported in 1960. In view of their broad applicability in pharmaceutics, it may be interesting to review their history, origin, evolution, potential advantages, limitations, and specific applications as green solvents. A chronological and comparative study of the literature showed the important role of DES in green approaches for modern pharmaceuticals. The concepts, applications, and outcomes of DES in pharmaceutical analysis, formulation/drug delivery, and pharmaceutical/medicinal chemistry are presented. A comprehensive outline of the atypical applications of DES as effective green solvents in pharmaceutical bioactive extraction was assessed. Efforts to present classifications of DES explored in pharmaceuticals were also made. The present manuscript also covers computational trend, adds on commercial aspects with potential future applications of DES in pharmaceutical sciences.

Tailor-made Biochar enhances the anti-tumour effects of butyrate-glycerides in colorectal cancer

Colorectal cancer (CRC) is the third most common cancer and the second cause of cancer death in the world. Emerging evidence suggests that the short-chain-fatty-acid butyrate diet-assumed or produced by gut microbiota may interfere with CRC. Novel, more focused and effective anti-cancer natural molecules selectively acting on tumour cells are required to improve patients' compliance compared to more aggressive drug-based schemes. This study explored the in vitro anti-cancer effects of a novel green compound consisting of butyrate-glycerides (BMDG) alone or absorbed on tailor-made Biochar (BMDG-Biochar) or on activated-carbon Norit-B (BMDG-Norit), by using two CRC cell lines, HCT116 and HT29. Tailor-made Biochar characterised by a larger share of meso and macroporosity compared to commercially available activated-carbon Norit-B, with micro-pored ultrastructure, displayed superior performances as a BMDG carrier, with higher absorption/release properties. BMDG, in particular when absorbed on Biochar, interfered significantly with CRC cell proliferation compared to BMDG-Norit that showed no effect. Analysis of cell metabolism revealed a superior sensitivity of HCT116 to the inhibitory effect of BMDG-Biochar. This compound specifically induced a shift from a glycolytic metabolism in particular in HCT116 cells where glycolysis supports the aggressive phenotype, towards the mitochondrial respiration that characterises the more differentiated and less aggressive HT29 cells. Biochar's ability to deliver the butyrate-glyceride bioactive mixture and to exert in vitro combined anti-cancer activity in colorectal cancer, interfering with the Warburg effect that characterises the aggressive CRC forms, opens future translational opportunities to develop new orally assumed green molecules as promising anti-cancer strategies for CRC.

Psoralidin acts as a dual protease inhibitor against PLpro and Mpro of SARS-CoV-2

The emergence of new coronavirus variants and concerns about vaccine effectiveness against these novel variants emphasize the need for broad-spectrum therapeutics targeting conserved coronaviral non-structural proteins. Accordingly, a virtual library of 178 putative inhibitors targeting SARS-CoV-2 Papain-like protease (PLpro) was compiled through a systematic review of published literature and subsequently screened using molecular docking. Selected hits were analyzed for protease inhibitory activities, binding strength, and antiviral activities against HCoV229E-based surrogate system and subsequently against SARS-CoV-2 for validation. Differences in potential modes of action were investigated using an HCoV229E-based system, combined with in silico and biophysical methods against SARS-CoV-2 system. Of the 178 hits, 13 molecules showed superior docking scores against PLpro and met the inclusion criteria for further investigations. Of these, seven showed notable inhibitory activities against PLpro. Particularly, both Psoralidin and Corylifol-A exhibited superior and, importantly, dual activities against SARS-CoV-2 Mpro. Both molecules were found to be biologically active against HCoV229E and SARS-CoV-2; however, Psoralidin exhibited more consistent effects and was relatively well-tolerated. Detailed in silico analyses of their interactions with the two proteases identified differences in their modes of action, primarily due to differences in their binding of PLpro. Based on these findings, we propose Psoralidin as a potential candidate for further development as a broad-spectrum antiviral and Corylifol-A as an ideal candidate for lead optimization.

Different mesoporous carbon carriers for the improvement of solubility and physical stability of poorly soluble drugs

Mesoporous carriers have gained significant attention for enhancing the solubility and bioavailability of Biopharmaceutics Classification System (BCS) Class II drugs. However, the contribution of mesoporous carriers with varying morphologies to the physical stability of these drugs is not well-defined. In this work, mesoporous carbon nanoparticles (MCN) and hollow carbon mesoporous nanoparticles (HMC) were prepared, while the weakly acidic Indomethacin (IMC) and alkaline Celecoxib (CXB) were incorporated into these carriers in the amorphous state by the solvent evaporation method. Notably, HMC demonstrated superior drug loading efficiencies (approximately 43 %) for both IMC and CXB owning to its hollow structure. The mesoporous drug loading systems significantly enhanced dissolution rates in comparison with both self-made amorphous drugs and raw drugs. Furthermore, under accelerated and long-term storage conditions, the mesoporous carriers effectively prevented drugs loaded from crystallization, maintaining constant dissolution profiles for over 12 months. Intriguingly, CXB exhibited a slower rate of crystallization after loading into the mesoporous carriers, likely due to the formation of hydrogen bonds between the carbonaceous carrier material and the amino groups of CXB. Compared with loaded drugs, the self-made amorphous drugs exhibited a crystallinity increase beyond 60 % within the initial month. Collectively, these findings highlighted the potential of mesoporous carbon carriers to elevate the dissolution behaviors of BCS Class II drugs while preserving the physical stability of the loaded amorphous drugs.

Novel Maleimide Linkers Based on a Piperazine Motif for Strongly Increased Aqueous Solubility

Maleimides remain very popular conjugation moieties in the fields of bio(in)organic chemistry and biotechnology. They are particularly interesting for endogenous albumin binding in the bloodstream to exploit the enhanced permeability and retention (EPR) effect and to increase tumor accumulation of anticancer drugs. However, during drug development, insufficient aqueous solubility is frequently a limiting factor. In the present study, four new maleimide linkers were synthesized containing a water-soluble piperazine scaffold. Respective maleimide-platinum(IV)-acetato complexes demonstrated similar hydrolytic stability, albumin-binding kinetics, in vivo serum pharmacokinetics and tissue distribution compared to a reference platinum(IV)-PEG4-maleimide complex. To test the aqueous solubility, platinum(IV)-maleimide complexes containing the highly lipophilic drug ibuprofen were synthesized. Indeed, the compounds containing the new piperazine linkers displayed increased solubility (up to 370 mM) in different aqueous media, whereas the PEG4-maleimide reference was only marginally soluble. Finally, the synthetic toolbox of the new piperazine maleimides was also expanded to pure organic derivatives by conjugation to valine-citrulline-para-aminobenzyl-OH derivatives via peptide and thiourea bonds.

High drug-loaded amorphous solid dispersions of a poor glass forming drug: The impact of polymer type and cooling rate on amorphous drug behaviour

Enhancing the aqueous solubility via amorphization of crystalline poor glass-forming drugs represents a challenge, particularly when drug dosing is high. In such scenarios, there is often a need for high polymer loadings, leading to an increase in the dosage form mass and less patient acceptability. This work investigated the role that polymer type and after-melt cooling rate had upon the amorphicity of solid dispersions (SDs) containing high levels of naproxen and three commonly used polymeric excipients: Eudragit® EPO, Kollidon® VA64, and Soluplus®. Using a combination of thermogravimetry, conventional and fast-scan DSC, oscillatory rheology, in silico Hansen solubility parameter computation, FTIR, and PXRD, we have shown that amorphicity could be affected by the cooling rate with the specific polymer type and amount playing a significant role in the degree of this impact. The amorphous drug content, evident at higher cooling rates, was found to be dependent on drug-polymer interaction and polymer melt viscosity. Higher polymer concentration and faster cooling produced less melt crystallization upon cooling, which was attributed to a shift in nucleation to lower temperatures where it could be inhibited by polymer matrix viscosity. Amorphous drug content, which contained drug nuclei, was evidenced by cold crystallization upon reheating. After 4 weeks of 'gentle' storage, cold crystallization increased if nucleation was the dominant process, whereas cold crystallization decreased if crystal growth prevailed. Storage at elevated temperature and humidity resulted in the absence of cold crystallization, and increased melt crystallisation. Thus, faster cooling could serve as an additional tool to improve amorphous yield and stability of high drug-loaded SDs, however, intermolecular polymer-drug interaction, melt viscosity of the drug-polymer matrix, and storage conditions are of critical importance to achieve this goal.

CFD modelling and simulations of atomization-based processes for production of drug particles: A review

Atomization-based techniques are widely used in pharmaceutical industry for production of fine drug particles due to their versatility and adaptability. Key performance measure of such techniques is their ability to provide control over critical quality attributes (CQAs) of produced drug particles. CQAs of drug particles produced via atomization critically depend on fluid dynamics of sprays; resulting mixing, heat and mass transfer; distribution of supersaturation and subsequent nucleation and growth of particles. It is essential to develop and use computational fluid dynamics (CFD) models for adequate understanding of multi-scale transport processes ranging from molecular scale mixing and particle scale processes, and from atomizer nozzle to overall spray chamber scale establishing relationships between CQAs and design and operating parameters of spray nozzle and chamber. In this work, we critically review past and current research efforts on CFD modelling of pharmaceutical atomization-based processes with an objective to provide clear assessment of the state of the art and to provide recommendations. An overview of the key atomization-based methods for producing drug particles with desired CQAs is presented. Key underlying physical processes and relevant concepts are then outlined. This discussion is related to the demands on CFD models; and state of the art is then discussed with respect to the process needs. Recommendations are provided towards higher fidelity and more efficient models of atomized multiphase flow dynamics and turbulence, drying modelling for the produced particles, and validation approaches. We conclude by highlighting a perceived need for numerical atomization studies with a pharmaceutical context; then, we deliver an outlook on current promising active control and machine learning strategies to augment the shift towards quality-by-design approaches in pharmaceutical manufacturing.

Large Language Model-Assisted Genotoxic Metal-Phenolic Nanoplatform for Osteosarcoma Therapy

Osteosarcoma, a leading primary bone malignancy in children and adolescents, is associated with a poor prognosis and a low global fertility rate. A large language model-assisted phenolic network (LLMPN) platform is demonstrated that integrates the large language model (LLM) GPT-4 into the design of multifunctional metal-phenolic network materials. Fine-tuned GPT-4 identified gossypol as a phenolic compound with superior efficacy against osteosarcoma after evaluating across a library of 60 polyphenols based on the correlation between experimental anti-osteosarcoma activity and multiplexed chemical properties of polyphenols. Subsequently, gossypol is then self-assembled into Cu2+-gossypol nanocomplexes with a hyaluronic acid surface modification (CuGOS NPs). CuGOS NPs has demonstrated the ability to induce genetic alterations and cell death in osteosarcoma cells, offering significant therapeutic benefits for primary osteosarcoma tumors and reducing metastasis without adverse effects on major organs or the genital system. This work presents an LLM-driven approach for engineering metal-organic nanoplatform and broadening applications by harnessing the capabilities of LLMs, thereby improving the feasibility and efficiency of research activities.

Nanotechnological approaches to improve corticosteroids ocular therapy

The administration of corticosteroids is the first-line treatment of the clinical conditions with ocular inflammation. Nonetheless, ocular physiological mechanisms, anatomical barriers and corticosteroid properties prevent it from reaching the target site. Thus, frequent topical administered doses or ocular injections are required, leading to a higher risk of adverse events and poor patient compliance. Designing novel drug delivery systems based on nanotechnological tools is a useful approach to overcome disadvantages associated with the ocular delivery of corticosteroids. Nanoparticle-based drug delivery systems represent an alternative to the current dosage forms for the ocular administration of corticosteroids, since due to their particle size and the properties of their materials, they can increase their solubility, improve ocular permeability, control their release and increase bioavailability after their ocular administration. In this way, lipid and polymer-based nanoparticles have been the main strategies developed, giving rise to novel patent applications to protect these innovative drug delivery systems as a product, its preparation or administration method. Additionally, it should be noted that at least 10 clinical trials are being carried out to evaluate the ocular application of different pharmaceutical formulations based on corticosteroid-loaded nanoparticles. Through a comprehensive and extensive analysis, this review highlights the impact of nanotechnology applications in ocular inflammation therapy with corticosteroids.

Enhancing drug solubility through competitive adsorption on silica nanosurfaces with ultrahigh silanol densities

We develop a technology based on competitive adsorption between drug molecules and water, specifically designed to address the critical issue of poor drug solubility. By specially engineering silica nanosurfaces with ultrahigh densities of silanol, we significantly enhance their affinity for both drug molecules and water, with a notably greater increase in water affinity. Such surfaces can effectively adsorb a variety of drug molecules under dry conditions. Upon exposure to water, these surfaces preferentially bind to water molecules, initiating a competitive adsorption process with the drug molecules. This competitive process turns water molecules from obstacles into catalysts for drug dissolution by actively displacing drug molecules from the surface, causing their rapid desorption and potentially enhancing their solubility by two to three orders of magnitude. The method is general, applicable to a wide array of drugs, stable for long-time storage, cost-effective, and scalable for mass production. Consequently, it has the potential to emerge as a next-generation platform for drug formulation and delivery.

Controlling Oral Polymicrobial Biofilm Using Usnic Acid on the Surface of Titanium in the Artificial Saliva Media

Background/Objectives: Titanium dental implants, while highly successful, face challenges due to polymicrobial infections leading to peri-implantitis and implant failure. Biofilm formation on implant surfaces is the primary cause of these infections, with factors such as matrix production and cross-kingdom interactions contributing to the microbial accumulation of bacterial and fungal pathogens species. To combat this issue, naturally derived molecules have been reported to overcome the hurdle of antimicrobial resistance against the application of conventional antibiotics and antifungals. Methods: The present study aimed to employ the lichen-derived molecules, usnic acid (UA), to retard the development of biofilms of bacterial and fungal pathogens on the surface of titanium kept in the human artificial saliva (HAS) working as a growth-supporting, host-mimicking media. Results: The minimum inhibitory concentration of UA in HAS towards Candida albicans was >512 µg/mL, whereas against Staphylococcus aureus and Streptococcus mutans, it was determined to be 512 µg/mL. Whereas, in the standard growth media, the MIC value of UA towards S. mutans and S. aureus were 8 and 16 µg/mL; however, against C. albicans, it was 512 µg/mL. UA synergistically enhanced the efficacy of the antibiotics toward bacterial pathogens and the efficacy of antifungals against C. albicans. The antibiofilm results depict the fact that in the HAS, UA significantly reduced both mono-species of S. mutans, S. aureus, and C. albicans and mixed-species biofilm of C. albicans with S. mutans and S. aureus on the surface of the titanium. Conclusions: The present study showed that UA is a promising natural drug that can control oral polymicrobial disease as a result of the application of dental implants.

Enhancing the Solubility of Co-Formulated Hydrophobic Drugs by Incorporating Functionalized Nano-Structured Poly Lactic-co-glycolic Acid (nfPLGA) During Co-Precipitation

Background/Objectives: The co-formulation of active pharmaceutical ingredients (APIs) is a growing strategy in biopharmaceutical development, particularly when it comes to improving solubility and bioavailability. This study explores a co-precipitation method to prepare co-formulated crystals of griseofulvin (GF) and dexamethasone (DXM), utilizing nanostructured, functionalized polylactic glycolic acid (nfPLGA) as a solubility enhancer. Methods: An antisolvent precipitation technique was employed to incorporate nfPLGA at a 3% concentration into the co-formulated GF and DXM, referred to as DXM-GF-nfPLGA. The dissolution performance of this formulation was compared to that of the pure drugs and the co-precipitated DXM-GF without nfPLGA. Results: Several characterization techniques, including electron microscopy (SEM), RAMAN, FTIR, TGA, and XRD, were used to analyze the nfPLGA incorporation and the co-precipitated co-formulations. The inclusion of nfPLGA significantly enhanced the dissolution and initial dissolution rate of both GF and DXM in the DXM-GF-nfPLGA formulation, achieving a maximum dissolution of 100%, which was not attained by the pure drugs or the DXM-GF formulation. The incorporation of nfPLGA also reduced the amount of time taken to reach 50% (T50) and 80% (T80) dissolution. T50 values decreased from 52 and 82 min (for pure DXM and GF) to 23 min for DXM-GF-nfPLGA, and the T80 improved to 50 min for DXM-GF-nfPLGA, significantly outpacing the pure compounds. Furthermore, incorporating nfPLGA into the crystal structures greatly accelerated the dissolution rates, with initial rates reaching 650.92 µg/min for DXM-GF-nfPLGA compared to 540.60 µg/min for DXM-GF, while pure GF and DXM showed lower rates. Conclusions: This work demonstrates that nfPLGA incorporation enhances dissolution performance by forming water channels within the API crystal via hydrogen-bonding interactions. This innovative nfPLGA incorporation method holds promise for developing hydrophobic co-formulations with faster solubility and dissolution rates.

High-Throughput Microarray Approaches for Predicting the Stability of Drug-Polymer Solid Dispersions

Amorphous solid dispersions (ASDs) offer a well-recognized strategy to improve the effective solubility and, hence, bioavailability of poorly soluble drugs. In this study, we developed an extensive library of a significant number of solid dispersion formulations using a library of chemically diverse drugs combined with a water-soluble polymer (polyvinylpyrrolidone vinyl acetate, PVPVA) at different loadings. These formulations were printed as microarrays of solid dispersion formulations, utilizing minimal material amounts (nanograms). They were subjected to a six-month stability study under accelerated conditions (40 °C and 75% relative humidity). Physical stability outcomes varied significantly among the different drug-polymer combinations, with stability ranging from immediate drug crystallization to several days of stability. The comprehensive data set obtained from this high-throughput screening was used to construct multiple linear regression models to correlate the stability of ASDs with the physicochemical properties of the used Active Pharmaceutical Ingredients (APIs). Our findings reveal that increased stability of ASDs is associated with a lower number of hydrogen bond acceptors alongside a higher overall count of heteroatoms and oxygen atoms in the drug molecules. This suggests that, while heteroatoms and oxygen are abundant, their role as hydrogen bond acceptors is limited due to their specific chemical environments, contributing to overall stability. Additionally, drugs with lower melting points formed more stable ASDs within the polymer matrix. This study, hence, highlights the importance of minimizing repulsive drug-polymer interactions to yield a physically stable ASD. The developed models, validated through Leave-One-Out Cross-Validation, demonstrated good predictability of stability trends. Hence, the high-throughput 2D inkjet printing technique that was used to manufacture the microarrays proved valuable for assessing drug-polymer crystallization onset risks and predicting stability outcomes. In conclusion, this study demonstrates a novel approach to solid dispersion formulation physical stability screening, enhancing efficiency, minimizing material requirements, and expanding the range of samples evaluated. Our findings provide insights into the critical physicochemical properties influencing ASD stability, offering a significant advancement in developing stable ASDs.

Improving oral absorption of a rapidly crystallizing parent drug using prodrug strategy: Comparison of phosphate versus glycine based prodrugs

With an increasing number of Biopharmaceutical Classification System (BCS) II/IV pipeline compounds, solubilizing and supersaturating formulation strategies are becoming prevalent. Beyond formulation and solid form strategies, prodrugs are also employed to overcome solubility-limited absorption of poorly water-soluble compounds. Prodrugs can potentially yield supersaturated systems upon conversion to the parent drug intraluminally and thus enhance absorption. However, supersaturation also increases the driving force for crystallization, resulting in low solution concentrations, which can potentially negate the advantage of prodrugs. In this work, two unique solubility-enhancing prodrugs, phosphate and glycine esters, were investigated for a rapidly crystallizing parent drug. Ex vivo absorption studies using rat tissue and in vivo studies in dogs were performed. Conversion rate of the phosphate prodrug to the parent was dependent on the milieu and increased ∼24-fold in the presence of intestinal contents as medium and tissue relative to neat buffer. In contrast, conversion of the glycine prodrug was minimal under any conditions tested, suggesting that the conversion occurs after absorption into the enterocytes. Phosphate prodrug showed a non-linear increase in parent drug absorptive flux across rat intestinal tissue with concentration when intestinal contents were used as donor media. This was attributed to rapid conversion and high supersaturation of the parent drug which subsequently resulted in crystallization at high doses in the donor chamber. Glycine prodrug did not undergo complete conversion at high doses and was absorbed unchanged on the basolateral side, indicating saturation of the converting enzymes in the enterocytes. The combined flux (parent drug and glycine) showed a linear increase with dose and crystallization was not observed. Under physiological conditions, glycine prodrug that is absorbed unchanged from the intestine can potentially undergo complete conversion in hepatocytes after absorption and make the parent drug systemically available. Thus, glycine prodrug provided overall higher absorption compared to phosphate prodrug. The observed flux levels for both the prodrugs were higher compared to the parent drug alone, highlighting an advantage to use of a prodrug strategy to improve absorption of such compounds. Oral dosing in a dog PK study revealed that the bioavailability using the phosphate prodrug was ∼50% whereas, it was ∼100% with glycine prodrug, supporting the in vitro observations.

Formation and stabilization mechanism of Ginsenoside Rg3 inclusion complexes based on molecular simulation

The formation of inclusion complexes between Ginsenoside Rg3 and cyclodextrins represents a promising strategy to enhance the solubility of G-Rg3. Nevertheless, the molecular mechanisms underlying the interaction between G-Rg3 and cyclodextrins have yet to be fully elucidated. In this study, we employed a combination of molecular simulation and experimental methodologies to identify the most effective solubilizing carriers among G-Rg3, β-cyclodextrin (β-CD), 2-hydroxypropyl-β-cyclodextrin (HP-β-CD), and 2,6-dimethyl-β-cyclodextrin (DM-β-CD). The inclusion complexes formed with HP-β-CD demonstrates superior stability and water solubility compared to those formed with β-CD and DM-β-CD. The preparation process for the inclusion complexes of G-Rg3 and HP-β-CD was optimized through an orthogonal testing approach. The optimal conditions were determined to be a mass ratio of G-Rg3 to HP-β-CD of 1:125, an inclusion time of 2 h, and an inclusion temperature of 30 °C. The formation of the inclusion complexes was confirmed using DSC, Fourier Transform Infrared FTIR, and XRD techniques. In vitro solubility tests indicated that the solubility of the G-Rg3 inclusion complexes was 2.9 times greater than that of G-Rg3. Molecular dynamics (MD) simulations provided insights into the mechanisms that stabilize the inclusion complexes and enhance their water solubility. The primary interaction force between G-Rg3 and HP-β-CD was identified as the van der Waals force.

Dissolution, phase behavior and mass transport of amorphous solid dispersions in aspirated human intestinal fluids

Amorphous solid dispersions (ASDs) typically show improved dissolution and generate supersaturated solutions, enhancing the oral bioavailability of poorly soluble drugs. To gain insights into intraluminal ASD behavior, we utilized two poorly soluble drugs with different crystallization tendencies, atazanavir and posaconazole, prepared as ASDs at a 10% drug loading with hydroxypropyl methylcellulose acetyl succinate (HPMCAS). We evaluated their release in aspirated fasted-state human intestinal fluid (FaHIF), and multi-component fasted-state simulated intestinal fluid (composite-FaSSIF), characterizing the supersaturation profiles and drug-rich nanodroplets that formed. Complete release was observed for atazanavir ASDs over a 90 min period. Flux for dissolved atazanavir ASDs remained high over the experimental time period of 3 h. In contrast, posaconazole solution concentrations were initially high and then decreased. Likewise, flux was initially high and then decreased where these changes are attributed to crystallization of the drug. Generation of spherical nano-sized amorphous droplets of ∼100-150 nm was found to occur in ex vivo FaHIF media for both ASDs, maximizing the diffusive flux during the supersaturation window. Moreover, buffer capacity differences were postulated to influence release rates of ASDs in simulated vs aspirated fluids. Importantly, the solution phase phenomena observed during ASD release in simulated fluids, namely amorphous nanodroplet formation and drug crystallization, were also found to occur in aspirated luminal fluids.

Dissolution of copovidone-based amorphous solid dispersions: Influence of atomic layer coating, hydration kinetics, and formulation

Atomic layer coating (ALC) is an emerging, solvent-free technique to coat amorphous solid dispersion (ASD) particles with a nanolayer ceramic coating that has been shown to improve powder characteristics and limit drug crystallization. Herein, we evaluate the impact of aluminum oxide coatings with varying thickness and conformality on the release behavior of ritonavir/copovidone ASDs. Release performance of powders, neat tablets, and formulated tablets was studied. Confocal fluorescence microscopy (CFM) was used to visualize particle hydration and phase separation during immersion of the ASD in aqueous media. CFM revealed particle hydration requires defects for solvent penetration, but coatings, regardless of thickness, had minor impacts on powder dissolution provided defects were present. In tablets where less surface area is exposed to the dissolution media due to gel formation, slowed hydration kinetics resulted in phase separation of the drug from the polymer in coated samples, limiting release. Formulation with two superdisintegrants, crospovidone and croscarmellose sodium, as well as lactose achieved ∼90% release in less than 10 minutes, matching the uncoated ASD particles of the same formulation. This study highlights the importance of hydration rate, as well as the utility of confocal fluorescence microscopy to provide insight into release and phase behavior of ASDs.

Investigating the effects of formulation variables on the disintegration of spray dried amorphous solid dispersion tablets

Amorphous solid dispersion (ASD) tablets based on hydrophilic polymer carriers may encounter disintegration challenges. In this work, the effect of different formulation composition variables on the ASD tablet disintegration performance was systematically studied. GDC-0334: copovidone (PVPVA) 60: 40 ASD prepared by spray drying was selected as the model ASD system. The effects of ASD loading, filler type and ratio, disintegrant type and level were then investigated using tablets made by direct compression process. Tablet disintegration time increased with the increase of ASD loading, especially when ASD loading exceeded 50 %. At the same tablet solid fraction, when lactose was used as the soluble filler, faster tablet disintegration was observed compared to the tablets with mannitol as the soluble filler. Among the three tested disintegrants, croscarmellose sodium performed the best in facilitating the ASD tablet disintegration, followed by sodium starch glycolate, and crospovidone was the poorest. When croscarmellose sodium was used as the disintegrant, 5 % level was sufficient to enable ASD tablet disintegration at 60 % ASD loading and further increase of croscarmellose sodium level to 8 % did not provide additional benefit. Water uptake experiments were performed on selected tablets and the results demonstrated a positive correlation with tablet disintegration time, indicating water penetration is a major contributing step for the disintegration of our ASD tablets. Overall, this work provides a rationale for excipient selection and insights into building a platform formulation approach for developing immediate-release ASD tablets.

Amorphous solubility advantage: Theoretical considerations, experimental methods, and contemporary relevance

Twenty-five years ago, Hancock and Parks asked a provocative question: "what is the true solubility advantage for amorphous pharmaceuticals?" Difficulties in determining the amorphous solubility have since been overcome due to significant advances in theoretical understanding and experimental methods. The amorphous solubility is now understood to be the concentration after the drug undergoes liquid-liquid or liquid-glass phase separation, forming a water-saturated drug-rich phase in metastable equilibrium with an aqueous phase containing molecularly dissolved drug. While crystalline solubility is an essential parameter impacting the absorption of crystalline drug formulations, amorphous solubility is a vital factor for considering absorption from supersaturating formulations. However, the amorphous solubility of drugs is complex, especially in the presence of formulation additives and gastrointestinal components, and concentration-based measurements may not indicate the maximum drug thermodynamic activity. This review discusses the concept of the amorphous solubility advantage, including a historical perspective, theoretical considerations, experimental methods for amorphous solubility measurement, and the contribution of supersaturation and amorphous solubility to drug absorption. Leveraging amorphous solubility and understanding the associated physicochemical principles can lead to more effective development strategies for poorly water-soluble drugs, ultimately benefiting therapeutic outcomes.

Bioavailability improvement by atomic layer coating: Fenofibrate a case study

Biopharmaceutical Classification Systems (BCS) class II drugs show poor solubility and high permeability in the body. Fenofibrate (FF) is a classic example of a BCS class II drug, used to treat high cholesterol and triglyceride (fat-like substances) levels in the blood. Atomic layer coating (ALC) is a surface engineering technology adapted from the semiconductor industry, where metal oxides are coated one atomic layer at a time over the active pharmaceutical ingredients (API) particles. ALC coating was proven to improve the processability, alter the hydrophilicity, improve the stability, and fine-tune the release of drugs. Herein, we report the intervention of ALC coating in enhancing the bioavailability of a poorly water-soluble drug (fenofibrate) in the animal model. The physical properties of uncoated fenofibrate were compared with those of zinc oxide-coated and silicon oxide-coated fenofibrate. Following the application of the coatings, the structural integrity (both chemical stability and solid-state stability) of the active pharmaceutical ingredient (API) remained uncompromised, as corroborated by 1H NMR and powder X-ray diffraction analyses. Notably, zinc oxide-coated fenofibrate exhibited favorable flow characteristics, whereas no discernible enhancement in flow behavior was observed for silicon oxide-coated fenofibrate. The results from contact angle measurements suggest that the silicon oxide-coated fenofibrate exhibits superior wetting behavior, as indicated by a contact angle nearing 0°. The application of ALC demonstrates an enhanced dissolution rate when compared to the uncoated active pharmaceutical ingredient (API) while leaving its equilibrium solubility unaffected. Coating the API with silicon oxide improves particle hydrophilicity and wetting properties, whereas zinc oxide coating aids in particle de-agglomeration, thereby enhancing their interaction with an aqueous medium. In vivo bioavailability studies conducted on rodents and larger animal (dog) models indicate a substantial increase in bioavailability (approximately 2 times) for the silicon oxide-coated API in comparison to the uncoated API, as determined by the area under the curve (AUC). Furthermore, the Cmax values for the silicon oxide-coated API also demonstrate a significant increase (approximately 3 times) over the uncoated API. Notably, an oral subacute toxicity study of ALC silicon-coated fenofibrate revealed no toxic effects attributable to the coating. This study underscores the potential of ALC in augmenting the bioavailability of BCS(II) drugs.

Impact of dissolution medium pH and ionization state of the drug on the release performance of amorphous solid dispersions

Amorphous solid dispersions (ASDs) are widely employed as a strategy to improve oral bioavailability of poorly water soluble compounds. Typically, optimal dissolution performance from a polyvinylpyrrolidone vinyl acetate (PVPVA) based ASD is observed at relatively low drug loading limit. Above a certain drug load, termed limit of congruency (LoC), the release from ASDs significantly decreases. So far, the majority of the dissolution behavior has been tested in conditions where the drug primarily exists in unionized form. In this work, the impact of pH of the dissolution environment on the release performance of ASDs of an ionizable drug was studied. Atazanavir (ATZ), a weakly basic drug with a pKa of 4.5 was used as a model compound and PVPVA was used as a non-ionizable matrix polymer. Dissolution rate was measured using Wood's apparatus which normalizes the surface area of the dissolving tablet. The pH of the dissolution media was varied between 1 and 6.8, to cover a range where ATZ exists as >99 % ionized or unionized species. At pH 6.8, near complete release was observed only when the drug load was ≤ 6 %. Unlike typically observed drastic decline in release behavior for PVPVA based ASDs above LoC, ATZ ASDs underwent gradual decline in dissolution behavior when the DL was increased to 8 %. This was attributed to potential formation of an ATZ-PVPVA associated phase with dissolution rate slower than neat PVPVA. However, the 10 % DL ASD showed negligible ATZ release. On another extreme (pH 1) where ATZ is ∼100 % ionized, the dissolution rate of ATZ was faster than that of PVPVA. ASD dissolution rate was found to be slower than that of the neat drug but faster than PVPVA and interestingly, did not change with DL. This can be attributed to formation of an ionized ATZ-PVPVA phase which controls the dissolution rate of the ASD. At pH 3, where the drug is ∼97 % ionized, near complete release was observed for drug loads ≤ 8 %. To observe significant increase in drug loading with near complete release, >98 % ionization of ATZ was required. At pH 2 where ATZ is ∼99.7 % ionized, near complete release was observed for drug loads up to 30 %. Furthermore, the deterioration in dissolution performance with an increase in drug load continued to be gradual at pH 2. The enhancement in dissolution performance did not correlate with solubility enhancement of ATZ due to ionization. We theorize that the enhancement in the dissolution performance due to ionization is the result of formation of an ionized ATZ-PVPVA phase which increases the hydrophilicity and the miscibility of the ASD. This can help resist water induced phase separation during ASD dissolution and therefore, result in continuous, and congruent dissolution of the drug and polymer.

Continuous twin-screw melt granulation of drug-loaded electrospun fibers

Electrospinning (ES) is a promising continuous formulation strategy to produce amorphous solid dispersions (ASDs) and thereby improve the dissolution of poorly water-soluble drugs. However, processing the electrospun material into solid dosage forms (e.g. tablets) is challenging due to the poor flow properties. In this research, continuous twin-screw melt granulation was applied to improve the flowability of the fibers and therefore ease the further processing steps. During this work, two ASD compositions were investigated: one containing 60 % poly-vinylpyrrolidone-vinyl acetate 6:4 copolymer and 40 % itraconazole (ITR), and another one containing hydroxypropyl methylcellulose (HPMC) and ITR in the same ratio. Both fiber compositions were granulated with polyethene glycol as the binder material, while the effects of the process parameters were examined. The application of higher granulation temperature and screw configurations with increased shear forces compromised the fibrous structure, induced crystallization of the ASD, and decreased the dissolution. However, the stability of the ITR-HPMC fibers proved to be higher as their granulation at 60 °C led to granules with adequate flow properties and dissolution. Moreover, tablets with fewer excipients were pressed from them, resulting in a 34 % reduction in weight. Consequently, this process can complement ES technology and facilitate its industrial implementation.

Formulation and optimization of transferrin-modified genistein nanocrystals: In vitro anti-cancer assessment and pharmacokinetic evaluation

In this research work, nanocrystals (NC) of poorly water-soluble drug genistein (Gen) were formulated to improve its aqueous solubility and bioavailability. Genistein nanocrystals (Gen-NC) were prepared by wet ball milling. The formulation was optimized using Box Behnken Design Expert to evaluate the impact of stabilizer concentration, drug concentration and quantity of zirconium beads (milling media) on NC size, polydispersity and zeta potential. The NCs were surface-decorated with transferrin (Tf) to form Tf modified Gen-NCs (Tf-Gen-NC) for improving cancer cell selectivity and cytotoxicity. The NC formulations were characterized by dynamic light scattering (DLS), scanning electron microscopy (SEM), Fourier transform infrared (FTIR) spectroscopy, X-ray power diffraction (XRD) and differential scanning calorimetry (DSC). The particle size distribution of the optimized formulation varied from 200 to 300 nm with poly dispersibility index (PDI) between 0.1 and 0.3. Tf-Gen-NC and Gen-NC released 96 % and 80 % of the drug content in 20 min at 37 °C, respectively, whereas only 18 % were released with the unprocessed drug. In vitro cytotoxicity was tested in pulmonary adenocarcinoma epithelial cells (A549) and fibroblast cell line (L929). The Tf-Gen-NC presented an enhanced anticancer effect. In vivo pharmacokinetic studies in mice after intraperitoneal administration showed that the Cmax of NC formulations were 2.5-fold higher compared to free Gen. The area under the curve from time of administration to 24 h was 2.5 to 3-fold higher when compared with unprocessed drug. This study shows the interest of Gen-NC in the development of new formulations for Gen as an anticancer drug.

Development of polymer-encapsulated microparticles of a lipophilic API-IL and its lipid based formulations for enhanced solubilisation

Active Pharmaceutical Ingredient-Ionic liquids (API-ILs) have the potential to improve the bioavailability of BCS Class IV Drugs. However, the problematic physical handling properties of room temperature API-ILs have impaired clinical and commercial exploitation to date. Lipid-based formulations (LBFs) are used to improve the absorption of drugs with limited bioavailability. Nonetheless, LBFs face limitations such as low drug loading capacity and sub-par physical stability. A platform for transforming API-ILs into solid forms at high loadings via spray encapsulation with polymers has been developed and previously demonstrated for hydrophilic API-ILs. The current work demonstrates that this platform technology can be applied to a lipophilic API-IL of the BCS Class IV API, chlorpromazine, and to multi-component solutions comprising API-IL and a LBF. Furthermore, solidification of a type IIIB, liquid LBF was achieved via spray encapsulation with cellulose- and methacrylate- based polymers for the first time. The spray-encapsulated formulations had excellent physical handling properties, and successfully eluted the API-IL in aqueous media. The chlorpromazine release profiles from the API-IL, the API-IL containing LBF, and the solidified formulations, were evaluated in vitro using phosphate buffer (pH 6.8) and fasted state simulated intestinal fluid (FaSSIF). Spray-encapsulated formulations exhibited improved release profiles compared to the liquid formulations. Overall, these findings indicate that phase-separated, polymeric, solid formulations of liquid API forms represent a promising platform technology for developing oral solid dosage forms of poorly bioavailable drugs.

Potential candidates from a functional food Zanthoxyli Pericarpium (Sichuan pepper) for the management of hyperuricemia: high-through virtual screening, network pharmacology and dynamics simulations

Introduction

Hyperuricemia (HUA) is a metabolic syndrome caused by purine metabolism disorders. Zanthoxyli Pericarpium (ZP) is a medicinal and food homologous plant, and its ripe peel is used to treat diseases and as a spice for cooking. Some studies have shown that ZP can inhibit the formation of xanthine oxidase and reduce the production of uric acid.

Methods

Through network pharmacology, ZP's potential targets and mechanisms for HUA treatment were identified. Databases like TCMSP, UniProt, and Swiss Target Prediction were utilized for ZP's active ingredients and targets. HUA-related targets were filtered using GeneCards, Drugbank, and Open Targets. Core targets for ZP's HUA treatment were mapped in a PPI network and analyzed with Cytoscape. GO and KEGG pathway enrichments were conducted on intersected targets via DAVID. Molecular docking and virtual screening were performed to find optimal binding pockets, and ADMET screening assessed compound safety. Molecular dynamics simulations confirmed compound stability in binding sites.

Results

We identified 81 ZP active ingredient targets, 140 HUA-related targets, and 6 drug targets, with xanthine dehydrogenase (XDH) as the top core target. Molecular docking revealed ZP's active ingredients had strong binding to XDH. Virtual screening via Protein plus identified 48 compounds near the optimal binding pocket, with 2'-methylacetophenone, ledol, beta-sitosterol, and ethyl geranate as the most promising. Molecular dynamics simulations confirmed binding stability, suggesting ZP's potential in HUA prevention and the need for further experimental validation.

Conclusion

Our study provides foundations for exploring the mechanism of the lowering of uric acid by ZP and developing new products of ZP. The role of ZP in the diet may provide a new dietary strategy for the prevention of HUA, and more experimental studies are needed to confirm our results in the future.

Supersaturated drug delivery system of albendazole salt-polymer complex for improving oral bioavailability and efficacy anti-secondary E. multilocularis

Based on the supersaturation theory, this study devised two albendazole (ABZ) salt-polymer complexes that enhance the oral bioavailability and efficacy of secondary hepatic alveolar echinococcosis (HAE) in rats. Solid characteristics, microstructure, and stability of ABZ benzenesulfonate (ABZ-BSA) and ABZ methanesulfonate (ABZ-MSA) were evaluated. The equilibrium solubility and intrinsic dissolution rate of salt were measured across different pH environments to determine its potential for generating supersaturation. Polymer crystallization inhibitors were subsequently introduced to assess their impact on sustaining supersaturation. The pharmacokinetics and anti-echinococcosis effects of ABZ were evaluated in healthy SD and HAE rats. The characteristic peaks corresponding to amino acid esters and benzimidazole in the ABZ salt structure either shifted or disappeared, corroborated by PXRD, signifying successful ABZ salt preparation. Furthermore, reductions in the melting point and enthalpy of the salts were observed, along with discernible differences in microstructure compared to ABZ. The drug salts exhibited a significant increase in apparent solubility and intrinsic dissolution rate of ABZ, thus laying the groundwork for supersaturation. Stability assessments indicated that salts were susceptible to moisture absorption, necessitating stringent humidity control measures. Notably, HPMC-AS demonstrated promising capabilities in sustaining supersaturation. Finally, pharmacokinetic analyses revealed a substantial increase in the AUC of ABZ-BSA-H and ABZ-MSA-H by 7.6 and 20.3 times, respectively, compared to ABZ in vivo. After a 30-day once-daily oral administration of the Salts and ABZ to SD rats with hepatic alveolar echinococcosis, the ABZ-BSA-H and ABZ-MSA-H formulation demonstrated a cysts inhibition effect 9.2-fold and 15.3-fold greater than that of ABZ. The salt-HPMC-AS complex could potentially be developed into an improved anti-AE drug therapy. Therefore, the salt-HPMC-AS complex could be developed into an enhanced anti-AE drug therapy.

Effects of chain length and saturation of triacylglycerols on the characteristics and gastrointestinal digestion fates of curcumin-loaded triacylglycerol nanoparticles

This study assessed the effects of fatty acid length and saturation on the physicochemical, thermal, and gastrointestinal digestive characteristics of curcumin-loaded homo-triacylglycerol nanoparticles (C-NPs). All C-NPs had good colloidal stability and efficiently entrapped curcumin, regardless of their length and saturation. Tricaprylin NPs, with shorter chains, had a smaller size and emulsifier surface load. Curcumin was released faster from low-melting C-NPs (tricaprylin and triolein) than those with high-melting-point (trimyristin, tripalmitin, and tristearin); however, both were negligible without lipolysis. None of the C-NPs underwent significant aggregation, coalescence, or breakdown during digestion before the small intestine. Notably, longer and more saturated chains resulted in a slower initial rate and lower degree of lipolysis in the small intestine. However, greater bioaccessibility of curcumin was observed only with longer chains (tricaprylin, 70.72%; trimyristin, 78.05%; tripalmitin, 85.09%; tristearin, 89.65%; triolein, 89.71%). These findings could be valuable for the development of rational curcumin formulations for functional foods.

Understanding the Impact of Lipids on the Solubilizing Capacity of Human Intestinal Fluids

Lipids in human intestinal fluids (HIF) form various structures, resulting in phase separation in the form of a lipid fraction and a micellar aqueous fraction. Currently used fed state simulated intestinal fluids (SIF) lack phase separation, highlighting the need for a deeper understanding of the effect of these fractions on intestinal drug solubilization in HIF to improve simulation accuracy. In this study, duodenal fluids aspirated from 21 healthy volunteers in fasted, early fed, and late fed states were used to generate 7 HIF pools for each prandial state. The apparent solubility of seven lipophilic model drugs was measured across these HIF pools, differentiating between the micellar fraction and the total sample (including both micellar and lipid fractions). The solubilizing capacities of these fluids were analyzed in relation to their composition, including total lipids, bile salts, phospholipids, total cholesterol, pH, and total protein. The solubility data generated in this work demonstrated that current fed state SIF effectively predicted the average solubility in the micellar fraction of HIF but failed to discern the considerable variability between HIF pools. Furthermore, the inclusion of a lipid fraction significantly enhanced the solubility of fed state HIF pools, resulting on average in a 13.9-fold increase in solubilizing capacity across the seven model compounds. Although the average composition of the fluids was consistent with previous studies, substantial variability was observed in micellar lipid concentrations, despite relatively stable total lipid concentrations. This variability is critical, as evidenced by the strong correlations between the solubilizing capacity of the micellar fraction and its micellar lipid concentrations. Additionally, this study identified that fluctuations in bile salt concentrations and pH contributed to the observed variability in micellar lipid concentration. In summary, the influence of the lipid fraction on solubility was 2-fold: it enhanced the solubility of lipophilic drugs in the total fluid, and contributed to the variability in the solubilizing capacity of the micellar fraction.

An aerosol nanocomposite microparticle formulation using rifampicin-cyclodextrin inclusion complexes for the treatment of pulmonary diseases

Rifampicin (RIF) is commonly used in the treatment of tuberculosis (TB), a bacterium that currently infects one fourth of the world's population. Despite the effectiveness of RIF in treating TB, current RIF treatment regimens require frequent and prolonged dosing, leading to decreased patient compliance and, ultimately, increased mortality rates. This project aims to provide an alternative to oral RIF by means of an inhalable spray-dried formulation. TB uses alveolar macrophages to hide and replicate until the cells rupture, further spreading the bacteria. Therefore, delivering RIF directly to the lungs can increase the drug concentration at the site of infection while reducing off-site side effects. Cyclodextrin (CD) was used to create a RIF-CD inclusion complex to increase RIF solubility and biodegradable RIF-loaded NP (RIF NP) were developed to provide sustained release of RIF. RIF NP and RIF-CD inclusion complex were spray dried to form a dry powder nanocomposite microparticles (nCmP) formulation (RIF-CD nCmP). RIF-CD nCmP displayed appropriate aerosol dispersion characteristics for effective deposition in the alveolar region of the lungs (4.0 µm) with a fine particle fraction of 89 %. The nCmP provided both a burst release of RIF due to the RIF-CD complex and pH-sensitive release of RIF due to the RIF NP incorporated into the formulation. RIF-CD nCmP did not adversely affect lung epithelial cell viability and RIF NP were able to effectively redisperse from the nCmP after spray drying. These results suggest that RIF-CD nCmP can successfully deliver RIF to the site of TB infection while providing both immediate and sustained release of RIF. Overall, the RIF-CD nCmP formulation has the potential to improve the efficacy for the treatment of TB.

Cocrystallization Enables Ensitrelvir to Overcome Anomalous Low Solubility Caused by Strong Intermolecular Interactions between Triazine-Triazole Groups in Stable Crystal Form

Ensitrelvir is a nonpeptide 3CL protease inhibitor used for coronavirus disease 2019 treatment. Four crystalline forms of ensitrelvir, metastable (Form I), acetonate (Form II), stable (Form III), and hydrate (Form IV), have been analyzed as pharmaceutical crystals. Their rank order of solubility is Form I > IV > III. Form III is the stable crystal with a significantly lower solubility than that predicted from its log P value of 2.7. Here, single-crystal structural analysis revealed strong intermolecular interactions between the triazine (acidic) and triazole (basic) groups of Form III not Forms I and IV. Multicomponent crystals were also designed to improve the solubility by altering the intermolecular interactions in Form III. Slurry conversion with equal molar ratios of ensitrelvir and fumaric acid successfully induced the formation of a novel cocrystal (Form V). Fumaric acid inhibited the triazine-triazole interactions, and dissolution of Form V was approximately 8- and 13-fold higher than that of Form III in pH 1.2 and 6.8 media, respectively. Furthermore, Form V exhibited an approximately 16-fold higher flux value than that of Form III. Therefore, alterations in intermolecular interactions via cocrystallization significantly enhance the dissolution and permeation of ensitrelvir.

The Particle Drifting Effect: A Combined Function of Colloidal and Drug Properties

The particle drifting effect, where nanosized colloidal drug particles overcome the diffusional resistance of the aqueous boundary layer adjacent to the intestinal wall and increase drug absorption rates, is drawing increasing attention in pharmaceutical research. However, mechanistic understanding and accurate prediction of the particle drifting effect remain lacking. In this study, we systematically evaluated the extent of the particle drifting effect affected by drug and colloidal properties, including the size, number, and type of the moving species using biphasic diffusion experiments combined with computational fluid dynamics simulations and mass transport analyses. The results showed that the particle drifting effect is a sequential reaction of particle dissolution/dissociation in the diffusional boundary layer, followed by absorption of the free drug. Therefore, factors affecting the rate-limiting step, which can be either process or both under different circumstances, alter the particle drifting effect. Experimental results also agree with the theory that the particle dissolution rate is dependent on particle size, concentration, and drug solubility. In addition, rapid bile micelle dissociation and bile salt absorption facilitated drug absorption by the particle drifting effect. Our findings explain the highly dynamic nature of the particle drifting effect and will contribute to rational formulation development and better bioavailability prediction for formulations containing colloidal particles.

Solubilization techniques used for poorly water-soluble drugs

About 40% of approved drugs and nearly 90% of drug candidates are poorly water-soluble drugs. Low solubility reduces the drugability. Effectively improving the solubility and bioavailability of poorly water-soluble drugs is a critical issue that needs to be urgently addressed in drug development and application. This review briefly introduces the conventional solubilization techniques such as solubilizers, hydrotropes, cosolvents, prodrugs, salt modification, micronization, cyclodextrin inclusion, solid dispersions, and details the crystallization strategies, ionic liquids, and polymer-based, lipid-based, and inorganic-based carriers in improving solubility and bioavailability. Some of the most commonly used approved carrier materials for solubilization techniques are presented. Several approved poorly water-soluble drugs using solubilization techniques are summarized. Furthermore, this review summarizes the solubilization mechanism of each solubilization technique, reviews the latest research advances and challenges, and evaluates the potential for clinical translation. This review could guide the selection of a solubilization approach, dosage form, and administration route for poorly water-soluble drugs. Moreover, we discuss several promising solubilization techniques attracting increasing attention worldwide.

Pharmaceutical approaches for enhancing solubility and oral bioavailability of poorly soluble drugs

High solubility in water and physiological fluids is an indispensable requirement for the pharmacological efficacy of an active pharmaceutical ingredient. Indeed, it is well established that pharmaceutical substances exhibiting limited solubility in water are inclined towards diminished and inconsistent absorption following oral administration, consequently resulting in variability in therapeutic outcomes. The current advancements in combinatorial chemistry and pharmaceutical design have facilitated the creation of drug candidates characterized by increased lipophilicity, elevated molecular size, and reduced aqueous solubility. Undoubtedly, the issue of poorly water-soluble medications has been progressively escalating over recent years. Indeed, 40% of the top 200 oral medications marketed in the United States, 33% of drugs listed in the US pharmacopoeia, 75% of compounds under development and 90% of new chemical entities are insufficiently water-soluble compounds. In order to address this obstacle, formulation scientists employ a variety of approaches, encompassing both physical and chemical methods such as prodrug synthesis, salt formation, solid dispersions formation, hydrotropic substances utilization, solubilizing agents incorporation, cosolvent addition, polymorphism exploration, cocrystal creation, cyclodextrins complexation, lipid formulations, particle size reduction and nanoformulation techniques. Despite the utilization of these diverse approaches, the primary reason for the failure in new drug development persists as the poor aqueous solubility of pharmaceutical compounds. This paper, therefore, delves into the foundational principles that underpin the implementation of various formulation strategies, along with a discussion on the respective advantages and drawbacks associated with each approach. Additionally, a discourse is provided regarding methodological frameworks for making informed decisions on selecting an appropriate formulation strategy to effectively tackle the key challenges posed during the development of a poorly water-soluble drug candidate.

Novel N-phenyl-2-(aniline) benzamide hydrochloride salt development for colon cancer therapy

Introduction

N-phenyl-2-(aniline) analog N53 is a previously discovered dual inhibitor of Topo I and COX-2, which exhibited significant anti-colon cancer activity in vitro, but the poor solubility and moderate anti-cancer activity in vivo hindered its further development.

Methods

To rectify the suboptimal drug properties of N53, a series of salt forms were developed and further evaluated through in vivo and in vitro experiments.

Results

The hydrochloride (N53·HCl) has a well-characterized crystal structure and its solubility reached 540.1 μg/mL, which is nearly 1,700 times higher than that of N53 (0.32 μg/mL). Increasing the N53 solubility consistently promotes its effective concentration, further enhancing the COX-2/Topo I inhibitory activity and the anti-tumor activity in vitro (IC50 values of 2.95 ± 0.08 μM for HT29 cells, 7.99 ± 0.85 μM for RKO cells, 10.94 ± 1.30 μM for HCT116 cells), as well as the anti-proliferative and pro-apoptotic activity. Meanwhile, its oral pharmacokinetic property in vivo is also improved. The elimination half-life (T1/2) is prolonged from 10.78 to 22.29 h, the maximum plasma concentration (Cmax) is increased 2-fold, and the area under the plasma drug concentration-time curve (AUC0-∞) is increased 3-fold. In colon cancer xenograft mouse models, the tumor inhibition rate of N53·HCl was 53.7%, superior to that of N53 (34.7%). Moreover, the results of HE staining showed that N53·HCl had no obvious toxic effects and side effects on other organs, indicating that it was safe in vivo.

Discussion

This study demonstrated that N53·HCl exhibits superior pharmacokinetic properties, anti-colon cancer efficacy, and safety, providing a promising drug candidate for colon cancer therapy.

Probabilistic prediction of material stability: integrating convex hulls into active learning

Active learning is a valuable tool for efficiently exploring complex spaces, finding a variety of uses in materials science. However, the determination of convex hulls for phase diagrams does not neatly fit into traditional active learning approaches due to their global nature. Specifically, the thermodynamic stability of a material is not simply a function of its own energy, but rather requires energetic information from all other competing compositions and phases. Here we present convex hull-aware active learning (CAL), a novel Bayesian algorithm that chooses experiments to minimize the uncertainty in the convex hull. CAL prioritizes compositions that are close to or on the hull, leaving significant uncertainty in other compositions that are quickly determined to be irrelevant to the convex hull. The convex hull can thus be predicted with significantly fewer observations than approaches that focus solely on energy. Intrinsic to this Bayesian approach is uncertainty quantification in both the convex hull and all subsequent predictions (e.g., stability and chemical potential). By providing increased search efficiency and uncertainty quantification, CAL can be readily incorporated into the emerging paradigm of uncertainty-based workflows for thermodynamic prediction.

Screening of Polymers for Oral Ritonavir Amorphous Solid Dispersions by Film Casting

Background/Objectives: Drug-polymer interactions and miscibility promote the formation and performance of amorphous solid dispersions (ASDs) of poorly soluble drugs for improved oral bioavailability. The objective of this study was to employ drug-polymer interaction calculations and small-scale experimental characterization to screen polymers for potential ASDs of ritonavir. Methods: Seven polymers across four polymer types were screened as follows: an enteric one (EudragitS100), amphiphilic ones (HPMCAS-L, HPMCAS-H, and their 1:1 combination), hydrophilic ones (PEG-6000, PVP-VA), and a surfactant (Soluplus), including PVP-VA as a positive control, as the commercial ASD employs PVP-VA. Drug-polymer interaction calculations were performed for Hansen solubility parameter, Flory-Huggins parameter, and glass transition temperature. ASDs were prepared via film casting. Experimental characterizations included drug solubility in polymer solutions, polymer inhibition of drug precipitation, polarized light microscopy, differential scanning calorimetry, solubilization capacity, and dissolution studies. Results: HPMCAS-L, HPMCAS L:H, and Soluplus, along with the positive control PVP-VA, were identified as polymers for potential ASDs of ritonavir, with HPMCAS-L and PVP-VA being preferable. HPMCAS-L and the positive control PVP-VA were always viable for both 20% and 40% drug loads across all tests. Films with each of these four polymers showed improved dissolution compared to amorphous ritonavir without polymer. Drug-polymer interaction calculations anticipated the unfavorable small-scale experimental results for PEG-6000 and EudragitS100. Conclusion: Overall, the results contribute towards a resource-sparing approach to identify polymers for ASDs.

Diffusive micromixing combined with dynamic in situ laser scattering allows shedding light on lipid nanoparticle precipitation

Pharmaceutical formulations are increasingly based on drug nanoparticles or carrier nanoparticles encapsulating drugs or mRNA molecules. Sizes and monodispersity of the nanoparticles regulate bioavailability, pharmacokinetics and pharmacology. Microfluidic mixers promise unique conditions for their continuous preparation. A novel microfluidic antisolvent precipitation device was realized by two-photon-polymerization with a mixing channel in which the organic phase formed a sheet with a homogeneous thickness of down to 7 μm completely wrapped in the aqueous phase. Homogeneous diffusion through the sheet accelerates mixing. Optical access was implemented to allow in-situ dynamic light scattering. By centering the thin sheet in the microchannel cross-section, two important requirements are met. On the one hand, the organic phase never reaches the channel walls, avoiding fouling and unstable flow conditions. On the other hand, in the sheet positioned at the maximum of the parabolic flow profile the nanoparticle velocities are homogenized which enables flow-compensated Dynamic Light Scattering (flowDLS). These unique features allowed in-situ particle size determination for the first time. Monitoring of lipid nanoparticle precipitation was demonstrated for different rates of solvent and antisolvent flows. This breakthrough innovation will not only enable feedback control of nanoparticle production but also will provide new insights into the dynamics of nanoparticle precipitation.

A Perspective on the Permeability of Cocrystals/Organic Salts of Oral Drugs

According to the BCS classification system, the differentiation of drugs is based on two essential parameters of solubility and permeability, meaning the latter is as pivotal as the former in creating marketable pharmaceutical products. Nevertheless, the indispensable role of permeability in pharmaceutical cocrystal profiles has not been sufficiently cherished, which can be most probably attributed to two principal reasons. First, responsibility may be on more user-friendly in vitro measurement procedures for solubility compared to permeability, implying the permeability measurement process seems unexpectedly difficult for researchers, whereas they have a complete understanding of solubility concepts and experiments. Besides, it may be ascribed to the undeniable attraction of introducing new crystal-based structures which mostly leaves the importance of improving the function of existing multicomponents behind. Bringing in new crystalline entities, to rephrase it, researchers have a fairly better chance of achieving high-class publications. Although the Food and Drug Administration (FDA) has provided a golden opportunity for pharmaceutical cocrystals to straightforwardly enter the market by simply considering them as derivatives of the existing active pharmaceutical ingredients, inattention to assessing and scaling up permeability which is intimately linked with solubility has resulted in limited numbers of them in the global pharmaceutical market. Casting a glance at the future, it is apprehended that further development in the field of permeability of pharmaceutical cocrystals and organic salts requires a meticulous perception of achievements to date and potentials to come. Thence, this perspective scrutinizes the pathway of permeation assessment making researchers confront their fear upfront through mapping the simplest way of permeability measurement for multicomponents of oral drugs.

FGF21 modulates immunometabolic homeostasis via the ALOX15/15-HETE axis in early liver graft injury

Fibroblast growth factor 21 (FGF21) is essential for modulating hepatic homeostasis, but the impact of FGF21 on liver graft injury remains uncertain. Here, we show that high FGF21 levels in liver graft and serum are associated with improved graft function and survival in liver transplantation (LT) recipients. FGF21 deficiency aggravates early graft injury and activates arachidonic acid metabolism and regional inflammation in male mouse models of hepatic ischemia/reperfusion (I/R) injury and orthotopic LT. Mechanistically, FGF21 deficiency results in abnormal activation of the arachidonate 15-lipoxygenase (ALOX15)/15-hydroxy eicosatetraenoic acid (15-HETE) pathway, which triggers a cascade of innate immunity-dominated pro-inflammatory responses in grafts. Notably, the modulating role of FGF21/ALOX15/15-HETE pathway is more significant in steatotic livers. In contrast, pharmacological administration of recombinant FGF21 effectively protects against hepatic I/R injury. Overall, our study reveals the regulatory mechanism of FGF21 and offers insights into its potential clinical application in early liver graft injury after LT.

Ciprofloxacin Derivative-Loaded Nanoparticles Synergize with Paclitaxel Against Type II Human Endometrial Cancer

Combinations of chemotherapeutic agents comprise a clinically feasible approach to combat cancers that possess resistance to treatment. Type II endometrial cancer is typically associated with poor outcomes and the emergence of chemoresistance. To overcome this challenge, a combination therapy is developed comprising a novel ciprofloxacin derivative-loaded PEGylated polymeric nanoparticles (CIP2b-NPs) and paclitaxel (PTX) against human type-II endometrial cancer (Hec50co with loss of function p53). Cytotoxicity studies reveal strong synergy between CIP2b and PTX against Hec50co, and this is associated with a significant reduction in the IC50 of PTX and increased G2/M arrest. Upon formulation of CIP2b into PEGylated polymeric nanoparticles, tumor accumulation of CIP2b is significantly improved compared to its soluble counterpart; thus, enhancing the overall antitumor activity of CIP2b when co-administered with PTX. In addition, the co-delivery of CIP2b-NPs with paclitaxel results in a significant reduction in tumor progression. Histological examination of vital organs and blood chemistry was normal, confirming the absence of any apparent off-target toxicity. Thus, in a mouse model of human endometrial cancer, the combination of CIP2b-NPs and PTX exhibits superior therapeutic activity in targeting human type-II endometrial cancer.

Supersolubilization and Amorphization of a Weakly Acidic Drug, Flurbiprofen, by applying Acid-Base supersolubilization (ABS) principle

Improvement in drug solubility is a major challenge for developing pharmaceutical products. It was demonstrated earlier that aqueous solubilities of weakly basic drugs could be increased greatly by interaction with weak acids that would not form salts with the drugs, and the highly concentrated solutions thus produced converted to amorphous solids upon drying. The technique was called acid-base supersolubilization (ABS). The current investigation explored whether the ABS principle could also be applied to weakly acidic drugs. By taking flurbiprofen (pKa 4.09; free acid solubility 0.011 mg/mL) as the model weakly acidic drug and tromethamine, lysine, meglumine, and NaOH as bases, it was studied which of the bases would result in ABS. While in the presence of NaOH and tromethamine, flurbiprofen converted to salts having aqueous solubility of 11-19 mg/mL, the solubility increased to > 399 mg/mL with lysine and > 358 mg/mL with meglumine, producing supersolubilization. However, crystallization of lysine salt was observed with time, followed by some decrease in solubility after reaching maximum solubility with lysine. In contrast, the supersolubilization was maintained with meglumine, and no crystallization of meglumine salt was observed. Upon drying, flurbiprofen-meglumine solutions produced amorphous materials that dissolved rapidly and produced high drug concentrations in aqueous media. Thus, the ABS principle also applies to acidic drugs depending on the weak base used.

Redox-manipulating nanocarriers for anticancer drug delivery: a systematic review

Spatiotemporally controlled cargo release is a key advantage of nanocarriers in anti-tumor therapy. Various external or internal stimuli-responsive nanomedicines have been reported for their ability to increase drug levels at the diseased site and enhance therapeutic efficacy through a triggered release mechanism. Redox-manipulating nanocarriers, by exploiting the redox imbalances in tumor tissues, can achieve precise drug release, enhancing therapeutic efficacy while minimizing damage to healthy cells. As a typical redox-sensitive bond, the disulfide bond is considered a promising tool for designing tumor-specific, stimulus-responsive drug delivery systems (DDS). The intracellular redox imbalance caused by tumor microenvironment (TME) regulation has emerged as an appealing therapeutic target for cancer treatment. Sustained glutathione (GSH) depletion in the TME by redox-manipulating nanocarriers can exacerbate oxidative stress through the exchange of disulfide-thiol bonds, thereby enhancing the efficacy of ROS-based cancer therapy. Intriguingly, GSH depletion is simultaneously associated with glutathione peroxidase 4 (GPX4) inhibition and dihydrolipoamide S-acetyltransferase (DLAT) oligomerization, triggering mechanisms such as ferroptosis and cuproptosis, which increase the sensitivity of tumor cells. Hence, in this review, we present a comprehensive summary of the advances in disulfide based redox-manipulating nanocarriers for anticancer drug delivery and provide an overview of some representative achievements for combinational therapy and theragnostic. The high concentration of GSH in the TME enables the engineering of redox-responsive nanocarriers for GSH-triggered on-demand drug delivery, which relies on the thiol-disulfide exchange reaction between GSH and disulfide-containing vehicles. Conversely, redox-manipulating nanocarriers can deplete GSH, thereby enhancing the efficacy of ROS-based treatment nanoplatforms. In brief, we summarize the up-to-date developments of the redox-manipulating nanocarriers for cancer therapy based on DDS and provide viewpoints for the establishment of more stringent anti-tumor nanoplatform.

Discovery and Preclinical Profile of ALG-055009, a Potent and Selective Thyroid Hormone Receptor Beta (THR-β) Agonist for the Treatment of MASH

Agonists of thyroid hormone receptor β (THR-β) decreased LDL cholesterol (LDL-C) and triglyceride (TG) levels in human clinical trials for patients with dyslipidemia. The authors present the highly potent and selective compound ALG-055009 (14) as a potential best in class THR-β agonist. The high metabolic stability and good permeability translated well in vivo to afford a long in vivo half-life pharmacokinetic profile with limited liability for DDI, and it overcomes certain drawbacks seen in recent clinical candidates.

Deep Eutectic Solvents Enhancing Drug Solubility and Its Delivery

Deep eutectic solvents (DES) are environmentally friendly solvents with the potential to dissolve bioactive compounds without affecting their characteristics. DES has special qualities that can be customized to meet the unique characteristics of a biomolecule/active pharmaceutical ingredient (API) in accordance with various therapeutic needs, providing a reliable approach in opening the door for the creation of cutting-edge drug formulations by resolving solubility issues in pharmaceutics. This study outlines newly developing approaches to solve the problem of inefficient API extraction due to poor solubility. These emerging strategies also have the capacity to alter the chemical and physical stability of API, which triggers drug's shelf life and their possible health benefits. It is anticipated that the highlighted methods and processes will be developed to capitalize on the DES potential to improve drug solubility and delivery in the pharmaceutical sector.

Patient-Centric Long-Acting Injectable and Implantable Platforms─An Industrial Perspective

The increasing focus on patient centricity in the pharmaceutical industry over the past decade and the changing healthcare landscape, driven by factors such as increased access to information, social media, and evolving patient demands, has necessitated a shift toward greater connectivity and understanding of patients' unique treatment needs. One pharmaceutical technology that has supported these efforts is long acting injectables (LAIs), which lower the administration frequency for the patient's provided convenience, better compliance, and hence better therapeutical treatment for the patients. Furthermore, patients with conditions like the human immunodeficiency virus and schizophrenia have positively expressed the desire for less frequent dosing, such as that obtained through LAI formulations. In this work, a comprehensive analysis of marketed LAIs across therapeutic classes and technologies is conducted. The analysis demonstrated an increasing number of new LAIs being brought to the market, recently most as aqueous suspensions and one as a solution, but many other technology platforms were applied as well, in particular, polymeric microspheres and in situ forming gels. The analysis across the technologies provided an insight into to the physicochemical properties the compounds had per technology class as well as knowledge of the excipients typically used within the individual formulation technology. The principle behind the formulation technologies was discussed with respect to the release mechanism, manufacturing approaches, and the possibility of defining predictive in vitro release methods to obtain in vitro in vivo correlations with an industrial angle. The gaps in the field are still numerous, including better systematic formulation and manufacturing investigations to get a better understanding of potential innovations, but also development of new polymers could facilitate the development of additional compounds. The biggest and most important gaps, however, seem to be the development of predictive in vitro dissolution methods utilizing pharmacopoeia described equipment to enable their use for product development and later in the product cycle for quality-based purposes.

Sophoraflavanone G: A review of the phytochemistry and pharmacology

Bioactive compounds derived from natural sources have long been investigated for the prevention and treatment of human diseases. Sophoraflavanone G (SFG), a lavandulyl flavanone naturally occurring in several Sophora plant species, belongs to the group of prenylated flavonoids that have garnered significant interest in contemporary research. The natural molecule exhibits a wide range of pharmacological properties and shows remarkable efficacy. Its ability to effectively suppress a range of malignant tumor cells, such as leukemia, breast cancer, and lung cancer, is attributed to its multi-target, multi-pathway, and multi-faceted mechanisms of action. Simultaneously, it can also alleviate various inflammatory diseases by mediating inflammatory mediators and molecular pathways. Furthermore, it has the capability to combat antibiotic resistance, exhibit synergistic antibacterial properties with diverse antibiotics, and prevent and treat various agricultural pests. Theoretically, it can bring benefits to human health and has potential value as a drug. Nevertheless, the drawbacks of poor water solubility and inadequate targeting cannot be overlooked. To comprehensively assess the current research on SFG, leverage its structural advantages and pharmacological activity, overcome its low bioavailability limitations, expedite its progression into a novel therapeutic drug, and better serve the clinic, this article presents a overall retrospect of the current research status of SFG. The discussion includes an analysis of the structural characteristics, physicochemical properties, bioavailability, pharmacological activities, and structure-activity relationships of SFG, with the goal of offering valuable insights and guidance for future research endeavors in this field.

Current Perspectives on Development and Applications of Cocrystals in the Pharmaceutical and Medical Domain

In recent years, the design of pharmaceutical cocrystals has garnered significant attention. The process of cocrystallization offers a remarkable opportunity to develop drug products with enhanced properties such as improved stability, solubility, hygroscopicity, dissolution rate, and bioavailability. This detailed review delves into this evolving area, thereby exploring its relevance in pharmaceutical formulation by defining cocrystals and their practical applications and also by discussing methods for their preparation as well as characterization. It also contrasts traditional and innovative techniques for cocrystal formation. Historically, cocrystals have been synthesized using methods like solvent evaporation, grinding, and slurry techniques; however, each has its own set of limitations under specific conditions. The latest trends in cocrystal formation lean toward more advanced approaches such as spray-drying, hot melt extrusion, and supercritical fluid technology, as well as the cutting-edge technique of laser irradiation. The aim behind developing new methods is not just to address the limitations of traditional cocrystallization techniques but also to streamline the process by introducing simpler steps and enabling a continuous production workflow for cocrystal products. In general, this full-length review article offers a report on various techniques available for the creation of pharmaceutical cocrystals, along with the methods for their evaluation. Moreover, it includes reporting developments and diverse applications of cocrystals along with the commercially available cocrystals in the pharmaceutical as well as medical domains.

Folic acid modified precision nanocarriers: charting new frontiers in breast cancer management beyond conventional therapies

Breast cancer presents a significant global health challenge, ranking highest incidence rate among all types of cancers. Functionalised nanocarriers offer a promising solution for precise drug delivery by actively targeting cancer cells through specific receptors, notably folate receptors. By overcoming the limitations of passive targeting in conventional therapies, this approach holds the potential for enhanced treatment efficacy through combination therapy. Encouraging outcomes from studies like in vitro and in vivo, underscore the promise of this innovative approach. This review explores the therapeutic potential of FA (Folic acid) functionalised nanocarriers tailored for breast cancer management, discussing various chemical modification techniques for functionalization. It examines FA-conjugated nanocarriers containing chemotherapeutics to enhance treatment efficacy and addresses the pharmacokinetic aspect of these functionalised nanocarriers. Additionally, the review integrates active targeting via folic acid with theranostics, photothermal therapy, and photodynamic therapy, offering a comprehensive management strategy. Emphasising rigorous experimental validation for practical utility, the review underscores the need to bridge laboratory research to clinical application. While these functionalised nanocarriers show promise, their credibility and applicability in real-world settings necessitate thorough validation for effective clinical use.

Natural Coptidis Rhizoma Nanoparticles Improved the Oral Delivery of Docetaxel

Purpose

Docetaxel (DTX) is a valuable anti-tumor chemotherapy drug with limited oral bioavailability. This study aims to develop an effective oral delivery system for DTX using natural nanoparticles (Nnps) derived from Coptidis Rhizoma extract.

Methods

DTX-loaded self-assembled nanoparticles (Nnps-DTX) were created using an optimized heat-induction strategy. Nnps-DTX's shape, size, Zeta potential, and in vitro stability were all carefully examined. Additionally, the study investigated the encapsulation efficiency, loading capacity, crystal form, and intermolecular interactions of DTX in Nnps-DTX. Subsequently, the solubility, release, cellular uptake, metabolic stability, and preclinical pharmacokinetics of DTX in Nnps-DTX were systematically evaluated. Finally, the cytotoxicity of Nnps-DTX was assessed in three tumor cell lines.

Results

Nnps-DTX was spherical in shape, 138.6 ± 8.2 nm in size, with a Zeta potential of -20.8 ± 0.6 mV, a DTX encapsulation efficiency of 77.6 ± 8.5%, and a DTX loading capacity of 6.8 ± 1.9%. Hydrogen bonds, hydrophobic interactions, and electrostatic interactions were involved in the formation of Nnps-DTX. DTX within Nnps-DTX was in an amorphous form, resulting in enhanced solubility (23.3 times) and release compared to free DTX. Following oral treatment, the mice in the Nnps-DTX group had DTX peak concentrations 8.8, 23.4, 44.6, and 5.7 times higher in their portal vein, systemic circulation, liver, and lungs than the mice in the DTX group. Experiments performed in Caco-2 cells demonstrated a significant increase in DTX uptake by Nnps-DTX compared to free DTX, which was significantly inhibited by indomethacin, an inhibitor of caveolae-mediated endocytosis. Furthermore, compared to DTX, DTX in Nnps-DTX demonstrated better metabolic stability in liver microsomes. Notably, Nnps-DTX significantly reduced the viability of MCF-7, HCT116, and HepG2 cells.

Conclusion

The novel self-assembled nanoparticles considerably enhanced the cellular absorption, solubility, release, metabolic stability, and pharmacokinetics of oral DTX and demonstrated strong cytotoxicity against tumor cell lines.