Mechanisms of increased bioavailability through amorphous solid dispersions: a review

Enhancing drug administration in Drosophila melanogaster: a method for using solid dispersions for improved solubility and bioavailability

Drosophila melanogaster is a widely used model organism for diseases such as Parkinson's disease, Alzheimer's disease, obesity, and diabetes. However, compound administration-based toxicological and behavioural studies on Drosophila have been hindered by technical difficulties associated with inefficient administration of hydrophobic compounds. This study illustrates a general method to make and distribute PEG 8000-based solid dispersions for three hydrophobic compounds, distearoylglycerol (DSG) geldanamycin (GA) and RU486 to D. melanogaster. The solid dispersions were validated, in vitro, using nuclear magnetic resonance spectroscopy (NMR), to have a higher aqueous solubility. The study also describes three different methods to administer the solid dispersions: subcutaneous injections, mixing in solid food, and the capillary feeder assay (CAFE). We show that the presence of 1% DMSO decreases survival, whereas PEG does not have an adverse effect. Lastly, we showed that the prepared PEG-RU486 formulation showed signs of enhanced bioavailability when compared to RU486 dissolved in ethanol. The methodology described in the study provides an easy and effective means to administer hydrophobic compounds to D. melanogaster using subcutaneous injections, CAFE assay, or by mixing it with solid food.

Comparative study of Hot-Melt Extrusion, spray drying, and KinetiSol® processing to formulate a poorly water-soluble and thermolabile drug

Fenbendazole (FBZ), a benzimidazole-carbamate anthelmintic, shows promising chemotherapeutic properties. However, it is a poorly water-soluble molecule, leading to low and variable oral bioavailability. This study investigated hot-melt extrusion (HME), spray drying, and KinetiSol processing (KSD) using Soluplus (SOL) to enhance FBZ's solubility. Formulating FBZ as an amorphous solid dispersion (ASD) by HME at a barrel temperature of 120 °C led to extensive chemical degradation of FBZ, generating the degradation product fenbendazoleamine. On the other hand, spray-drying (SD) generated an ASD, but its usefulness was greatly limited by the low solubility of FBZ in the cosolvent system required in the SD process. Given FBZ's poor solubility in both water and organic solvents and its thermolabile propensity, KSD was explored. Conventional KSD parameters reduced the impurity levels to 6.4 % at a discharge temperature of 64 °C. To further minimize impurity levels, we investigated alternative KSD parameters that terminate the process before reaching the melt agglomeration phase. These conditions resulted in powder-discharged KSD samples (pKSD) that avoided causing chemical degradation of FBZ. The pKSD samples exhibited trace crystallinity, as confirmed by Wide Angle X-ray Scattering (WAXS). Scanning electron microscopy (SEM) revealed that these samples comprised nano- and micron-sized particle aggregates. These results were confirmed by processing FBZ with other excipients, such as semi-crystalline polymers and cyclodextrins. The pKSD samples demonstrated improved dissolution performance of FBZ compared to the physical mixture and crystalline neat FBZ due to the smaller particle size of FBZ. pKSD FBZ provides a solution for formulating thermolabile molecules like FBZ while only requiring a few seconds of exposure to the pKSD manufacturing process conditions, thus eliminating the disadvantages of SD (e.g., requiring sufficiently high solubility in the organic solvent system) and HME (e.g., exposure to high shear and heat during the process).

Uniform Spray Dried Loxapine Microparticles Potentially for Nasal Delivery: Exploring Discriminatory In Vitro Release Evaluation Methods

This study aimed to develop suitable in vitro evaluation methods for the release behavior of nasal powders (NPs). We synthesized a range of standardized microparticles with adjustable size and morphology by co-spray-drying loxapine succinate (LOX) and gelatin (GEL) using an ethanol/water solvent mixture in a self-designed micro-fluidic jet spray dryer (MFJSD). The influence of the LOX/GEL mass ratio and solvent composition on particle characteristics, including size, morphology, and crystalline properties, was systematically investigated. In vitro release profiles of NPs were thoroughly assessed across different release medium, apparatus, and membranes. The modified Transwell® system, utilizing simulated nasal electrolyte solution (SNES) as the release medium, was identified as the most effective in distinguishing the performance of microparticles with diverse attributes. Furthermore, the impact of particle size, morphology, and crystalline properties on in vitro release profiles was discussed. This research presents a robust methodology for the in vitro evaluation of NPs release profiles and provides a practical approach for the rational fabrication of high-quality NPs products.

High-Pressure Dielectric Spectroscopic Studies of Amorphous CBD: Investigating Molecular Dynamics and Physical Stability Under Manufacturing Conditions of the Pharmaceuticals

Objectives: This study highlighted the key role played by high-pressure (HP) dielectric spectroscopic measurements of amorphous CBD to probe the molecular dynamics in order to examine the physical stability of the drug. The pharmacological properties of CBD assure that this can be a promising drug for the pharmaceutical industry. Hence, it is important to check the physical stability under elevated temperature and pressure conditions to understand the behavior of the drug under manufacturing conditions. Methods: This research investigated the molecular dynamics at various temperatures and pressures. We utilized the HP dielectric studies which are considered as an advanced and sensitive tool to determine both the molecular dynamics and the phase transformations. Results: This paper discusses the physical stability by analyzing the behavior of structural relaxation and crystallization tendencies of the amorphous drug under ambient and elevated pressure conditions. This study verified that amorphous CBD is highly physically stable at storage and elevated temperature conditions under ambient pressure. Conclusions: Accordingly, we examined the physical stability under elevated pressures at storage temperature, and we observed that the compression induced the crystallization of amorphous CBD. The breaking of weak hydrogen bonds present in the CBD might be the reason for this destabilization at elevated pressures. The least physical stability at high-pressure conditions was also confirmed by the broadening of the α-relaxation peak at high pressures.

On-Demand Nitric Oxide Generation via Thermal Decomposition of N-Trityl Dihydro-1,2-Oxazines

Inhaled nitric oxide (iNO) is a promising therapy for a variety of pulmonary conditions but is limited by the cost, portability, and safety limitations of the compressed gas cylinders used in conventional iNO delivery systems. On-demand generation of iNO via thermally controlled decomposition of an NO-genic precursor is an attractive alternative to systems based on compressed gas cylinders. However, most NO-releasing materials, which would form the basis of such a system, are designed for in vivo applications, but not for gas flow release at elevated temperatures. Novel NO donors with tunable kinetics suited for simple thermal generation are needed to realize such iNO delivery systems. Here we report the development of a new class of NO donors based on N-trityl 3,6-dihydro-1,2-oxazines. We show that amorphous solid dispersions of these molecules in porous polymers exhibit consistent, thermoresponsive NO release in good yields when heated above 90 °C in the presence of a carrier gas. We further demonstrate that these donors undergo NO release in aqueous media at 37 °C. Collectively, this work adds a new class of NO donor to the basis set of known NO-genic molecules and establishes a potential chemical basis for a low-power, small-footprint iNO delivery system.

Prodrug Approach as a Strategy to Enhance Drug Permeability

Absorption and permeability are critical physicochemical parameters that must be balanced to achieve optimal drug uptake. These key factors are closely linked to the maximum absorbable dose required to provide appropriate plasma levels of drugs. Among the various strategies employed to enhance drug solubility and permeability, prodrug design stands out as a highly effective and versatile approach for improving physicochemical properties and enabling the optimization of biopharmaceutical and pharmacokinetic parameters while mitigating adverse effects. Prodrugs are compounds with reduced or no activity that, through bio-reversible chemical or enzymatic processes, release an active parental drug. The application of this technology has led to significant advancements in drug optimization during the design phase, and it offers broad potential for further development. Notably, approximately 13% of the drugs approved by the U.S. Food and Drug Administration (FDA) between 2012 and 2022 were prodrugs. In this review article, we will explore the application of prodrug strategies to enhance permeability, describing examples of market drugs. We also describe the use of the prodrug approach to optimize PROteolysis TArgeting Chimeras (PROTACs) permeability by using conjugation technologies. We will highlight some new technologies in prodrugs to enrich permeability properties, contributing to developing new effective and safe prodrugs.

Developing Soluplus®-Based Microparticle Amorphous Solid Dispersions with High Drug Loading for Enhanced Celecoxib Dissolution via Electrospraying

Amorphous solid dispersion (ASD) is one of the most studied strategies for improving the dissolution performance of poorly water-soluble drugs, but ASDs often have low drug loadings, thereby necessitating larger dosage sizes. This study intended to create Soluplus® (SOL)-based microparticle ASDs with high drug loading (up to 60 w/w%) and long-term stability (at least 16 months) using electrospraying to enhance the dissolution of poorly water-soluble celecoxib (CEL). X-ray diffraction (XRD) and differential scanning calorimetry (DSC) analyses showed that the electrosprayed SOL-CEL microparticles were amorphous, and Fourier transform infrared spectroscopy (FTIR) data indicated the presence of hydrogen bonding between SOL and CEL in the microparticles, which helped stabilize the ASDs. In vitro dissolution studies demonstrated that these ASDs improved the CEL dissolution rate by up to 8.2-fold compared to the crystalline form. Electrospraying presents a promising alternative to conventional methods like hot-melt extrusion (HME) and spraying drying (SD) for the production of ASDs, providing simplicity, high drug loading capability and long-term stability, thus catering to a variety of poorly water-soluble drugs.

Solid dispersion of alectinib HCl: preclinical evaluation for improving bioavailability and establishing an IVIVC model

OBJECTIVE

Alectinib HCl (ALB-HCl) is a BCS class IV molecule with low solubility and low oral bioavailability. Owing to its low bioavailability, a high dose of ALB-HCl is recommended with food to meet clinical efficacy. Thus, there is a need for a delivery system to overcome the bioavailability concerns.

METHODS

Three solid dispersion (SD) formulations (I, II, and III) were evaluated for in-vitro dissolution and in-vivo pharmacokinetics (PK) study in Wistar rats. An in-vitro and in-vivo correlation (IVIVC) model was developed to establish a relationship between in-vitro dissolution data and in-vivo PK data. The formulations were subjected to stability studies.

RESULTS

All formulations showed enhanced dissolution in all the media except Formulation I in FaSSIF media. In-vivo PK studies displayed that Formulation I was inferior to API alone. Formulations II and III (amorphous SD [ASD]) exhibited two-fold higher Cmax and AUC0-last than API alone. Level A IVIVC model was established for Cmax and AUC0-last with an acceptable % prediction error (PE). When evaluated for external predictability, the model was found validated for Cmax (% PE <10%), however, it was inconclusive for AUC0-last (%PE -14.03). Stability studies showed ASD formulations were stable during storage.

CONCLUSION

A stable ASD formulation of ALB-HCl was successfully developed with improved bioavailability. Developing an IVIVC model can act as a surrogate to predict in-vivo performance. The selection of formulation components in ASD shall be rationalized for bioavailability and stability before clinical evaluation.

Changes in drug crystallinity in a commercial tacrolimus amorphous formulation result in variable pharmacokinetics

Tacrolimus capsules contain the drug as the amorphous form. It is well known that drug crystallinity is a risk factor for the performance of amorphous formulations. This study investigated the impact of varying levels of crystalline drug on the pharmacokinetics of tacrolimus following oral dosing of a 5 mg capsule under fasting conditions. Two treatments with percent crystallinity of 20% and 50% were achieved by exposing a marketed generic tacrolimus product to open dish storage conditions of 35 °C and 75% relative humidity (RH) for up to 20 days. Crystallinity was monitored with X-ray powder diffraction. Prograf®, the reference listed drug (RLD), an amorphous generic drug product, and generic drug products containing 20% and 50% crystalline tacrolimus were evaluated. All four treatments were administered to healthy participants in a randomized, single-dose, four-treatment, four-period, four-way crossover study. Blood sampling occurred over 24 h. The amorphous generic tacrolimus product was determined not to be bioequivalent to the RLD. The capsules containing both 20% and 50% crystalline tacrolimus also failed the bioequivalence recommendations when compared to the amorphous generic or to the RLD. Both levels of crystalline tacrolimus resulted in BE failure for both Cmax and AUC parameters. The impact of tacrolimus crystallization was greater for maximum blood concentration (Cmax) values relative to the area-under-the-curve (AUC) values. This study demonstrates that crystalline tacrolimus formed in a marketed generic product and these changes resulted in variable pharmacokinetics which could be of significant clinical concern.

Application of atomic force microscopy in the development of amorphous solid dispersion

Development of Amorphous Solid Dispersion (ASD) requires an in-depth characterization at different stages due to its structural and functional complexity. Various tools are conventionally used to investigate the processing, stability, and functionality of ASDs. However, many subtle features remain poorly understood due to lack of nano-scale characterization tools in routine practice. Atomic force microscopy (AFM) is a type of scanning probe microscopy, used for high resolution imaging and measuring features at the nano-scale. In recent years AFM has been used increasingly as a characterization tool in different areas of the development of ASD, including drug-polymer miscibility, localized characterization of the phase separated domains, lateral molecular diffusivity on ASD surface, crystallinity and crystallization kinetics in ASD, phase behavior of ASD during dissolution, and conformation of polymer during dissolution. In this review, we have highlighted the current applications of AFM in capturing critical aspects of stability and dissolution behavior of ASD. Potential areas of future development in this domain have been discussed.

Vehicle effect on in-vitro and in-vivo performance of spray-dried dispersions

In early drug development, amorphous spray-dried dispersions (SDDs) applied to enhance the bioavailability of poorly water-soluble compounds are typically administered to preclinical species via oral gavage in the form of suspensions. The liquid formulations are usually prepared on the same day of dosing to minimize the exposure of the amorphous material to the aqueous vehicle, thereby reducing the risk of crystallization. Dose-ability (e.g. syringe-ability) of the suspensions is also a critical factor for the administration, particularly when high doses, thus concentrations, are required for toxicology studies. As a result, it is standard practice during early formulation screening to assess the stability and the maximum feasible concentration of SDDs in various vehicles. In this study, we evaluated the impact of different vehicles on the performance of a model SDD in-vitro and in-vivo settings, to mitigate the risks associated with its administration in liquid form. A poorly water-soluble compound (GEN-A) was selected to screen various SDDs and generate the SDD model at 30 % drug load with HPMCAS-MF polymer carrier. The SDD was suspended in selected aqueous vehicles after a careful vehicle components screening, that included suspending agents (HPC-SL), solubilizers (PEG400, Propylene glycol), surfactants (Vitamin E TPGS, SLS, Tween 80, Poloxamer 188), and complexing agents (HP-β-CD, SBE-β-CD). The suspensions were characterized for stability, dose-ability and dissolution in biorelevant media, prior administration in pre-clinical species. The SDD dissolution profile revealed that the drug's supersaturation level was positively impacted by the presence of a surfactant (SLS) and a complexing agent (SBE-β-CD) with respect to a suspending agents (HPC-SL) in the vehicle. Similarly, the pharmacokinetics profiles of the drug following the administration of the SDD in a vehicle with a complexing agent (SBE-β-CD) achieved greater exposure compare to the SDD in a vehicle with a suspending agent (HPC-SL). These findings confirm a synergistic effect between the SDD and the vehicles, suggesting that this combination could be leveraged to maximize the advantages of the amorphous approach.

Quantification of soluplus for dissolution tests: SEC method development and validation

The quantification of both polymer and drug during the dissolution of an amorphous solid dispersion (ASD) in aqueous media arouses great interest and may aid in the formulation. However, the available quantification methods for polymer excipients are limited, expensive, and challenging compared to drugs. In this work, a size exclusion chromatography method (HPLC-SEC) was developed and validated to determine the concentration of a frequently used polymer excipient, Soluplus® (Sol). In order to develop a method for the quantification of dissolved Soluplus®, two methods (SEC-UV and SEC-RID) with two injection volumes were tested with standard solutions of three different batches of Soluplus. The developed HPLC-SEC-UV method showed acceptable linearity (R2 > 0.9990) for all batches of Soluplus, good accuracies above a concentration of 0.1 mg/mL (coefficient of variation < 2 %), relatively good precision at a concentration of 0.1 mg/mL (coefficient of variation < 2.5 %), and high recoveries at a concentration of 0.75 mg/mL (coefficient of variation < 0.5 %). The presence of Felodipine (Fel) and Lumefantrine (Lum) in the liquid media did not interfere with Soluplus quantification. The use of various surfactants, such as Tween® 80, Tween® 20, Span® 80, Span® 20, Kolliphor® TPGS, and sodium lauryl sulphate at a low concentration (0.005 mg/mL) did not show any effect on Soluplus® and did not interfere with Soluplus® quantification with any of the Soluplus batches. The addition of lithium bromide (LiBr) to the mobile phase within a concentration range of 0.05-1.0 M did not improve Soluplus® quantification.

Impact of surfactants on solution behavior and membrane transport of amorphous solid dispersions

The purpose of the study was to develop an amorphous solid dispersion (ASD) of a poorly soluble compound (AK100) and investigate the impact of different surfactants on its dissolution, supersaturation and membrane transport. The solubility of the AK100 was determined in crystalline and amorphous form in the absence and presence of three surfactants at different concentrations: sodium dodecyl sulphate (SDS), polysorbate 80 (PS80) and D-α-tocopherol polyethylene glycol succinate (TPGS). The relation between solubility and surfactant solubilization was evaluated using a computational model. The ASD powder was prepared by solvent evaporation for non-sink dissolution experiments with and without the pre-dissolved surfactants. A transport study with Caco-2 cells was conducted to evaluate the impact of surfactants-based formulation on membrane transport. Both the corresponding crystalline and amorphous solubility of AK100 increased linearly as a function of the surfactant concentrations. The supersaturation was maintained for at least three hours in absence of surfactant and in presence of TPGS, whereas supersaturation declined with SDS and PS80. As expected, the membrane flux of the AK100 was higher for the ASD than for the crystalline powder, and further increased with increased concentration of TPGS. The supersaturation ratio based on the activity-based calculation from Caco-2 cells study was always higher than that of the concentration-based one for the amorphous and crystalline forms of AK100. This study shows how additional solubilizing excipients during formulation development can improve the resulting dissolution and phase behavior of supersaturated drug solution.

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.

Application of the Box-Behnken Design in the Development of Amorphous PVP K30-Phosphatidylcholine Dispersions for the Co-Delivery of Curcumin and Hesperetin Prepared by Hot-Melt Extrusion

Background: Curcumin and hesperetin are plant polyphenols known for their poor solubility. To address this limitation, we prepared amorphous PVP K30-phosphatidylcholine dispersions via hot-melt extrusion. Methods: This study aimed to evaluate the effects of the amounts of active ingredients and phosphatidylcholine, as well as the process temperature, on the performance of the dispersions. A Box-Behnken design was employed to assess these factors. Solid-state characterization and biopharmaceutical studies were then conducted. X-ray powder diffraction (XRPD) was used to confirm the amorphous nature of the dispersions, while differential scanning calorimetry (DSC) provided insight into the miscibility of the systems. Fourier-transform infrared spectroscopy (FTIR) was employed to assess the intermolecular interactions. The apparent solubility and dissolution profiles of the systems were studied in phosphate buffer at pH 6.8. In vitro permeability across the gastrointestinal tract and blood-brain barrier was evaluated using the parallel artificial membrane permeability assay. Results: The quantities of polyphenols and phospholipids were identified as significant factors influencing the biopharmaceutical performance of the systems. Solid-state analysis confirmed the formation of amorphous dispersions and the development of interactions among components. Notably, a significant improvement in solubility was observed, with formulations exhibiting distinct release patterns for the active compounds. Furthermore, the in vitro permeability through the gastrointestinal tract and blood-brain barrier was enhanced. Conclusions: The findings suggest that amorphous PVP K30-phosphatidylcholine dispersions have the potential to improve the biopharmaceutical properties of curcumin and hesperetin.

Advancing the Physicochemical Properties and Therapeutic Potential of Plant Extracts Through Amorphous Solid Dispersion Systems

Plant extracts demonstrate significant potential as a rich source of active pharmaceutical ingredients, exhibiting diverse biological activities and minimal toxicity. However, the low aqueous solubility of extracts and their gastrointestinal permeability, as well as their poor oral bioavailability, limit clinical advancements due to drug delivery problems. An amorphous solid dispersion (ASD) delivers drugs by changing an active pharmaceutical ingredient (API) into an amorphous state to increase the solubility and availability of the API to the body. This research aimed to analyze and summarize the successful advancements of ASD systems derived from plant extracts, emphasizing characterization and the effects on dissolution and pharmacological activity. The results show that ASD systems improve phytoconstituent dissolution, bioavailability, and stability, in addition to reducing dose and toxicity. This research demonstrates the significance of ASD in therapeutic formulations to augment the pharmacological activities and efficacy of medicinal plant extracts. The prospects indicate promising potential for therapeutic applications utilizing ASD systems, alongside medicinal plant extracts for clinical therapy.

Dynamic Phase Behavior of Amorphous Solid Dispersions Revealed with In Situ Stimulated Raman Scattering Microscopy

This study reports the application of in situ stimulated Raman scattering (SRS) microscopy for real-time chemically specific imaging of dynamic phase phenomena in amorphous solid dispersions (ASDs). Using binary ritonavir and poly(vinylpyrrolidone-vinyl acetate) films with different drug loadings (0-100% w/w) as model systems, we employed SRS microscopy with fast spectral focusing to analyze ASD behavior upon contact with a dissolution medium. Multivariate unmixing of the SRS spectra allowed changes in the distributions of the drug, polymer, and water to be (semi)quantitatively imaged in real time, both in the film and the adjacent dissolution medium. The SRS analyses were further augmented with complementary correlative sum frequency generation and confocal reflection for additional crystallinity and phase sensitivity. In the ASDs with drug loadings of 20, 40, and 60% w/w, the water penetration front within the film, followed by both surface-directed and bulk phase separation in the film, was apparent but differed quantitatively. Additionally, drug-loading and phase-dependent polymer and drug release behavior was imaged, and liquid-liquid phase separation was observed for the 20% drug loading ASD. Overall, SRS microscopy with fast spectral focusing provides quantitative insights into water-induced ASD phase phenomena, with chemical, solid-state, temporal, and spatial resolution. These insights are important for optimal ASD formulation development.

In vitro and in vivo performance of amorphous solid dispersions of ursolic acid as a function of polymer type and excipient addition

OBJECTIVES

The objective of this research was to enhance the bioavailability of ursolic acid (UA) by preparing multielement amorphous solid dispersion (ASD) systems comprising excipients.

METHODS

The ASDs were prepared via the solvent evaporation method, characterized by a range of techniques, and investigated with respect to permeability of human colorectal adenocarcinoma cell line (Caco-2) cells monolayers and pharmacokinetics, with comparisons made to the physical mixture and the pure drug.

KEY FINDINGS

The (UA-choline)-Polyethylcaprolactam-polyvinyl acetate-polyethylene glycol grafted copolymer (Soluplus)-Vitamin E polyethylene glycol succinate (TPGS) ASD demonstrated superior dissolution properties compared to the corresponding binary solid dispersions and ternary solid dispersions (P< .05). The permeability studies of Caco-2 cell monolayers revealed that the ASD exhibited moderate permeability, with an efflux rate that was significantly lower than that of the UA raw material (P< .05). Pharmacokinetic studies in rats demonstrated that the oral bioavailability of the ASD was 19.0 times higher than that of UA (P< .01).

CONCLUSIONS

The research indicated that the multielement ASD could be employed as an efficacious drug delivery system for UA. Furthermore, the Soluplus/TPGS/choline combination represents a promising candidate for the fabrication of ASDs that can load weakly acidic and poorly soluble drugs.

Improve Solubility and Develop Personalized Itraconazole Dosages via Forming Amorphous Solid Dispersions with Hydrophilic Polymers Utilizing HME and 3D Printing Technologies

Itraconazole (ITZ), a broad-spectrum triazole antifungal agent, exhibits remarkable pharmacodynamic and pharmacokinetic properties. However, the low solubility of ITZ significantly reduces its oral bioavailability. Furthermore, it has been reported that this medication can result in dose-related adverse effects. Therefore, the objective of this study was to enhance the solubility of ITZ through the utilization of various polymers and to manufacture personalized and programmable release ITZ tablets. Five different polymers were selected as water-soluble carriers. Thirty percent w/w ITZ was mixed with seventy percent w/w of the polymers, which were then extruded. A series of physical and chemical characterization studies were conducted, including DSC, PXRD, PLM, and in vitro drug release studies. The results demonstrated that ITZ was dispersed within the polymers, forming ASDs that markedly enhanced its solubility and dissolution rate. Consequently, soluplus® was employed as the polymer for the extrusion of ITZ-loaded filaments, which were subsequently designed and printed. The in vitro drug release studies indicated that the release of ITZ could be regulated by modifying the 3D structure design. Overall, this study found that the combination of HME and 3D printing technologies could represent an optimal approach for the development of personalized and precise drug delivery dosages.

Antitubercular Activity of 7-Methyljuglone-Loaded Poly-(Lactide Co-Glycolide) Nanoparticles

BACKGROUND/OBJECTIVES

Loading of natural products into poly-(lactide-co-glycolic) acid (PLGA) nanoparticles as drug delivery systems for the treatment of diseases, such as tuberculosis (TB), has been widely explored. The current study investigated the use of PLGA nanoparticles with 7-methyljuglone (7-MJ), an active pure compound, isolated from the roots of Euclea natalensis A. DC.

METHODS

7-MJ as well as its respective PLGA nanoparticles were tested for their antimycobacterial activity against Mycobacterium smegmatis (M. smegmatis), drug-susceptible Mycobacterium tuberculosis (M. tuberculosis) (H37Rv), and multi-drug-resistant M. tuberculosis (MDR11). The cytotoxicity of 7-MJ as well as its respective PLGA nanoparticles were tested for their cytotoxic effect against differentiated human histiocytic lymphoma (U937) cells. Engulfment studies were also conducted to determine whether the PLGA nanoparticles are taken up by differentiated U937 cells.

RESULTS

7-MJ has been shown to have a minimum inhibitory concentration (MIC) value of 1.6 µg/mL against M. smegmatis and multi-drug-resistant M. tuberculosis and 0.4 µg/mL against drug-susceptible M. tuberculosis. Whilst promising, 7-MJ was associated with cytotoxicity, with a fifty percent inhibition concentration (IC50) of 3.25 µg/mL on differentiated U937 cells. In order to lower the cytotoxic potential, 7-MJ was loaded into PLGA nanoparticles. The 7-MJ PLGA nanoparticles showed an 80-fold decrease in cytotoxic activity compared to free 7-MJ, and the loaded nanoparticles were successfully taken up by differentiated macrophage-like U937 cells.

CONCLUSIONS

The results of this study suggested the possibility of improved delivery during TB therapy via the use of PLGA nanoparticles.

Amorphous Solid Dispersion Formation for Enhanced Release Performance of Racemic and Enantiopure Praziquantel

Praziquantel (PZQ) is the treatment of choice for schistosomiasis, which affects more than 250 million people globally. Commercial tablets contain the crystalline racemic compound (RS-PZQ) which limits drug dissolution and oral bioavailability and can lead to unwanted side effects and poor patient compliance due to the presence of the S-enantiomer. While many approaches have been explored for improving PZQ's dissolution and oral bioavailability, studies focusing on investigating its release from amorphous solid dispersions (ASDs) have been limited. In this work, nucleation induction time experiments were performed to identify suitable polymers for preparing ASDs using RS-PZQ and R-PZQ, the therapeutically active enantiomer. Cellulose-based polymers, hydroxypropyl methylcellulose acetate succinate (HPMCAS, MF grade) and hydroxypropyl methylcellulose (HPMC, E5 LV grade), were the best crystallization inhibitors for RS-PZQ in aqueous media and were selected for ASD preparation using solvent evaporation (SE) and hot-melt extrusion (HME). ASDs prepared experimentally were subjected to X-ray powder diffraction to verify their amorphous nature and a selected number of ASDs were monitored and found to remain physically stable following several months of storage under accelerated-stability testing conditions. SE HPMCAS-MF ASDs of RS-PZQ and R-PZQ showed faster release than HPMC E5 LV ASDs and maintained good performance with an increase in drug loading (DL). HME ASDs of RS-PZQ formulated using HPMCAS-MF exhibited slightly enhanced release compared to that of SE ASDs. SE HPMCAS-MF ASDs showed a maximum release increase of the order of 6 times compared to generic and branded (Biltricide) PZQ tablets. More importantly, SE R-PZQ ASDs with HPMCAS-MF released the drug as effectively as RS-PZQ or better, depending on the DL used. These findings have significant implications for the development of commercial PZQ formulations comprised solely of the R-enantiomer, which can result in mitigation of the biopharmaceutical and compliance issues associated with current commercial tablets.

Polymers Enhance Chlortetracycline Hydrochloride Solubility

Chlortetracycline hydrochloride (CTC) is a broad-spectrum tetracycline antibiotic with a wide range of antibacterial activities. Due to low solubility, poor stability, and low bioavailability, clinical preparation development is limited. We sought to improve these solubility and dissolution rates by preparing solid dispersions. A hydrophilic polymer was selected as the carrier, and a solid dispersion was prepared using a medium grinding method, with samples characterized by scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), powder X-ray diffraction (PXRD), Fourier-transform infrared spectroscopy (FT-IR), and particle size distribution (PSD). To maximize CTC solubility and stability, different polymer types and optimal drug-to-polymer ratios were screened. The solubility of optimized povidone K30 (PVPK30) (1/0.75, w/w)-, hydroxypropyl-β-cyclodextrin (HP-β-CD) (1/2, w/w)-, and gelatin (1/1, w/w)-based solid dispersions was 6.25-, 7.7-, and 3.75-fold higher than that of pure CTC powder, respectively. Additionally, in vitro dissolution studies showed that the gelatin-based solid dispersion had a higher initial dissolution rate. SEM and PS analyses confirmed that this dispersion had smaller and more uniform particles than PVPK30 and HP-β-CD dispersions. Therefore, successful solid polymer dispersion preparations improved the CTC solubility, dissolution rates, and stability, which may have potential as drug delivery systems.

Surface Solid Dispersion of Ketoconazole on Trehalose Dihydrate using Spray Drying to Achieve Enhanced Dissolution Rate

Ketoconazole (K) is a poorly water-soluble drug that faces significant challenges in achieving therapeutic efficacy. This study aimed to enhance the dissolution rate of ketoconazole by depositing spray-dried ketoconazole (SK) onto the surface of ground trehalose dihydrate (T) using spray drying. Ketoconazole-trehalose surface solid dispersions (SKTs) were prepared in ratios of 1:1 (SK1T1), 1:4 (SK1T4), and 1:10 (SK1T10), and characterized them using particle size analysis, scanning electron microscopy, powder X-ray diffraction, and in vitro dissolution studies. Results showed that the dissolution rates of the dispersions were significantly higher than those of pure ketoconazole, with the 1:10 ratio showing the highest dissolution rate. The improved dissolution was attributed to the formation of a new crystalline phase and better dispersion of ketoconazole particles. These findings suggest that the surface solid dispersion approach could be a valuable method for enhancing the bioavailability of poorly water-soluble drugs.

Revisiting Niclosamide Formulation Approaches - a Pathway Toward Drug Repositioning

Niclosamide (NIC), an anthelmintic drug, has garnered recent attention for its potential as an antiviral, antibacterial, and chemotherapeutic agent, among other applications. Repurposing NIC presents a current trend, offering significant time and cost savings compared to developing entirely new therapeutic chemical entities. However, its drawback lies in poor solubility, resulting in notably low oral bioavailability. This review consolidates efforts to overcome this limitation by summarizing twelve categories of formulations, spanning derivatives, amorphous solid dispersions, co-crystals, nanocrystals, micelles, nanohybrids, lipid nanoparticles and emulsions, cyclodextrins, polymeric nanoparticles, dry powders for inhalation, 3D printlets, and nanofibers. These formulations cover oral, injectable, inhalable and potentially (trans)dermal routes of administration. Additionally, we present a comprehensive overview of NIC characteristics, including physico-chemical properties, metabolism, safety, and pharmacokinetics. Moreover, we identify gaps in formulation and administration pathways that warrant further investigation to address NIC poor bioavailability.

Enhanced Bioavailability and Reduced Variability of Dasatinib and Sorafenib with a Novel Amorphous Solid Dispersion Technology Platform

Despite clinical advances with protein kinase inhibitors (PKIs), oral administration of many PKIs is associated with highly variable plasma exposure and a narrow therapeutic window. We developed a novel hybrid nanoparticle-amorphous solid dispersion (ASD) technology platform consisting of an amorphous PKI embedded in a polymer matrix. The technology was used to manufacture immediate-release formulations of 2 tyrosine kinase inhibitors (TKIs), dasatinib and sorafenib. Our primary objective was to improve the absorption properties and reduce the pharmacokinetic (PK) variability of each TKI. The PKs of XS004 (dasatinib-ASD, 100 mg tablet) and XS005 (sorafenib-ASD, 2 × 50 mg capsules) were compared with their crystalline formulated reference drugs (140 mg of dasatinib-reference and 200 mg of sorafenib-reference). The in vitro biopharmaceutics of dasatinib-ASD and XS005-granulate showed sustained increased solubility in the pH range 1.2-8.0 compared to their crystalline references. In vivo, XS004 was bioequivalent at a 30% lower dose and showed increased absorption and bioavailability, with 2.1-4.8 times lower intra- and intersubject variability compared to the reference. XS005 had an increased absorption and bioavailability of 45% and 2.2-2.8 times lower variability, respectively, but it was not bioequivalent at the investigated dose level. Taken together, the formulation platform is suited to generate improved PKI formulations with consistent bioavailability and a reduced pH-dependent absorption process.

Different or the same? exploring the physicochemical properties and molecular mobility of celecoxib amorphous forms

The influence of different preparation methods on the physicochemical properties of amorphous solid forms have gained considerable attention, especially with recent publications on pharmaceutical polyamorphism. In the present study, we have investigated the possible occurrence of polyamorphism in the drug celecoxib (CEL) by investigating the thermal behavior, morphology, structure, molecular mobility and physical stability of amorphous CEL obtained by quench-cooling (QC), ball milling (BM) and spray drying (SD). Similar glass transition temperatures but different recrystallization behaviors were observed for CEL-QC, CEL-BM and CEL-SD using modulated differential scanning calorimetry analysis. A correlation between the different recrystallization behaviors of the three CEL amorphous forms and the respective distinct powder morphologies, was also found. Molecular dynamics simulations however, reveal that CEL presents similar molecular conformational distributions when subjected to QC and SD. Moreover, the obtained molecular conformational distributions of CEL are different from the ones found in its crystal structure and also from the ones found in the lowest-energy structure obtained by quantum mechanical calculations. The type and strength of CEL hydrogen bond interactions found in CEL-QC and CEL-SD systems are almost identical, though different from the ones presented in the crystal structure. Pair distribution function analyses and isothermal microcalorimetry show similar local structures and structural relaxation times, respectively, for CEL-QC, CEL-BM and CEL-SD. The present work shows that not only similar physicochemical properties (glass transition temperature, and structural relaxation time), but also similar molecular conformational distributions were observed for all prepared CEL amorphous systems. Hence, despite their different recrystallization behaviors, the three amorphous forms of CEL did not show any signs of polyamorphism.

Preparation, Characterization and Evaluation of Nintedanib Amorphous Solid Dispersions with Enhanced Oral Bioavailability

The dissolution and bioavailability challenges posed by poorly water-soluble drugs continue to drive innovation in pharmaceutical formulation design. Nintedanib (NDNB) is a typical BCS class II drug that has been utilized to treat idiopathic pulmonary fibrosis (IPF). Due to the low solubility, its oral bioavailability is relatively low, limiting its therapeutical effectiveness. It is crucial to enhance the dissolution and the oral bioavailability of NDNB. In this study, we focused on the preparation of amorphous solid dispersions (ASD) using hot melt extrusion (HME). The formulation employed Kollidon® VA64 (VA64) as the polymer matrix, blended with the NDNB at a ratio of 9:1. HME was conducted at temperatures ranging from 80 °C to 220 °C. The successful preparation of ASD was confirmed through various tests including polarized light microscopy (PLM), X-ray powder diffraction (XRPD), differential scanning calorimetry (DSC), Fourier-transform infrared spectroscopy (FT-IR), and thermogravimetric analysis (TGA). The in-vitro cumulative release of NDNB-ASD in 2 h in a pH 6.8 medium was 8.3-fold higher than that of NDNB (p < 0.0001). In a pH 7.4 medium, it was 10 times higher (p < 0.0001). In the in-vivo pharmacokinetic experiments, the area under curve (AUC) of NDNB-ASD was 5.3-fold higher than that of NDNB and 2.2 times higher than that of commercially available soft capsules (Ofev®) (p < 0.0001). There was no recrystallization after 6 months under accelarated storage test. Our study indicated that NDNB-ASD can enhance the absorption of NDNB, thus providing a promising method to improve NDNB bioavailability in oral dosages.

Enhanced Dissolution of Amphotericin B through Development of Amorphous Solid Dispersions Containing Polymer and Surfactants

Amphotericin B (AmB) is the gold standard for antifungal therapy; however, its poor solubility limits its administration via intravenous infusion. A promising formulation strategy to achieve an oral formulation is the development of amorphous solid dispersions (ASDs) via spray-drying. Inclusion of surfactants into ASDs is a newer concept, yet it offers increased dissolution opportunities when combined with a polymer (HPMCAS 912). We developed both binary ASDs (AmB:HPMCAS 912 or AmB:surfactant) and ternary ASDs (AmB:HPMCAS 912:surfactant) using a variety of surfactants to determine the optimal surfactant carbon chain length and functional group for achieving maximal AmB concentration during in vitro dissolution. The ternary ASDs containing surfactants with a carbon chain length of 14 ± 2 carbons and a sulfate functional group increased the dissolution of AmB by 90-fold compared to crystalline AmB. These same surfactants, when added to a binary ASD, however, were only able to achieve up to a 40-fold increase, alluding to a potential interaction occurring between excipients or excipient and drug. This potential interaction was supported by dynamic light scattering data, in which the ternary formulation produced a single peak at 895.2 dnm. The absence of more than one peak insinuates that all three components are interacting in some way to form a single structure, which may be preventing AmB self-aggregation, thus improving the dissolution concentration of AmB.

Amorphous Polymer-Phospholipid Solid Dispersions for the Co-Delivery of Curcumin and Piperine Prepared via Hot-Melt Extrusion

Curcumin and piperine are plant compounds known for their health-promoting properties, but their use in the prevention or treatment of various diseases is limited by their poor solubility. To overcome this drawback, the curcumin-piperine amorphous polymer-phospholipid dispersions were prepared by hot melt extrusion technology. X-ray powder diffraction indicated the formation of amorphous systems. Differential scanning calorimetry confirmed amorphization and provided information on the good miscibility of the active compound-polymer-phospholipid dispersions. Owing to Fourier-transform infrared spectroscopy, the intermolecular interactions in systems were investigated. In the biopharmaceutical properties assessment, the improvement in solubility as well as the maintenance of the supersaturation state were confirmed. Moreover, PAMPA models simulating the gastrointestinal tract and blood-brain barrier showed enhanced permeability of active compounds presented in dispersions compared to the crystalline form of individual compounds. The presented paper suggests that polymer-phospholipid dispersions advantageously impact the bioaccessibility of poorly soluble active compounds.

System-agnostic prediction of pharmaceutical excipient miscibility via computing-as-a-service and experimental validation

We applied computing-as-a-service to the unattended system-agnostic miscibility prediction of the pharmaceutical surfactants, Vitamin E TPGS and Tween 80, with Copovidone VA64 polymer at temperature relevant for the pharmaceutical hot melt extrusion process. The computations were performed in lieu of running exhaustive hot melt extrusion experiments to identify surfactant-polymer miscibility limits. The computing scheme involved a massively parallelized architecture for molecular dynamics and free energy perturbation from which binodal, spinodal, and mechanical mixture critical points were detected on molar Gibbs free energy profiles at 180 °C. We established tight agreement between the computed stability (miscibility) limits of 9.0 and 10.0 wt% vs. the experimental 7 and 9 wt% for the Vitamin E TPGS and Tween 80 systems, respectively, and identified different destabilizing mechanisms applicable to each system. This paradigm supports that computational stability prediction may serve as a physically meaningful, resource-efficient, and operationally sensible digital twin to experimental screening tests of pharmaceutical systems. This approach is also relevant to amorphous solid dispersion drug delivery systems, as it can identify critical stability points of active pharmaceutical ingredient/excipient mixtures.

Bridging the gap between target-based and phenotypic-based drug discovery

INTRODUCTION

The unparalleled progress in science of the last decades has brought a better understanding of the molecular mechanisms of diseases. This promoted drug discovery processes based on a target approach. However, despite the high promises associated, a critical decrease in the number of first-in-class drugs has been observed.

AREAS COVERED

This review analyses the challenges, advances, and opportunities associated with the main strategies of the drug discovery process, i.e. based on a rational target approach and on an empirical phenotypic approach. This review also evaluates how the gap between these two crossroads can be bridged toward a more efficient drug discovery process.

EXPERT OPINION

The critical lack of knowledge of the complex biological networks is leading to targets not relevant for the clinical context or to drugs that present undesired adverse effects. The phenotypic systems designed by considering available molecular mechanisms can mitigate these knowledge gaps. Associated with the expansion of the chemical space and other technologies, these designs can lead to more efficient drug discoveries. Technological and scientific knowledge should also be applied to identify, as early as possible, both drug targets and mechanisms of action, leading to a more efficient drug discovery pipeline.

Nucleotides as new co-formers in co-amorphous systems: Enhanced dissolution rate, water solubility and physical stability

Developing co-amorphous systems is an attractive strategy to improve the dissolution rate of poorly water-soluble drugs. Various co-formers have been investigated. However, previous studies revealed that it is a challenge to develop satisfied acidic co-formers, e.g., acidic amino acids showed much poorer co-former properties than neutral and basic amino acids. Only a few acidic co-formers have been reported, such as aspartic acid, glutamic acid, and some other organic acids. Thus, this study aims to explore the possibility of adenosine monophosphate and adenosine diphosphate used as acidic co-formers. Mebendazole, celecoxib and tadalafil were used as the model drugs. The drug-co-former co-amorphous systems were prepared via ball milling and confirmed using XRPD. The dissolution study suggested that the solubility and dissolution rate of the drug-co-formers systems were increased significantly compared to the corresponding crystalline and amorphous drugs. The stability study revealed that using the two nucleotides as co-formers enhanced the physical stability of pure amorphous drugs. Molecular interactions were observed in MEB-co-former and TAD-co-former systems and positively affected the pharmaceutical performance of the investigated co-amorphous systems. In conclusion, the two nucleotides could be promising potential acidic co-formers for co-amorphous systems.

Enhancing hepatoprotective action: oxyberberine amorphous solid dispersion system targeting TLR4

Oxyberberine (OBB) is a significant natural compound, with excellent hepatoprotective properties. However, the poor water solubility of OBB hinders its release and absorption thus resulting in low bioavailability. To overcome these drawbacks of OBB, amorphous spray-dried powders (ASDs) of OBB were formulated. The dissolution, characterizations, and pharmacokinetics of OBB-ASDs formulation were investigated, and its hepatoprotective action was disquisitive in the D-GalN/LPS-induced acute liver injury (ALI) mouse model. The characterizations of OBB-ASDs indicated that the crystalline form of OBB active pharmaceutical ingredients (API) was changed into an amorphous form in OBB-ASDs. More importantly, OBB-ASDs showed a higher bioavailability than OBB API. In addition, OBB-ASDs treatment restored abnormal histopathological changes, improved liver functions, and relieved hepatic inflammatory mediators and oxidative stress in ALI mice. The spray drying techniques produced an amorphous form of OBB, which could significantly enhance the bioavailability and exhibit excellent hepatoprotective effects, indicating that the OBB-ASDs can exhibit further potential in hepatoprotective drug delivery systems. Our results provide guidance for improving the bioavailability and pharmacological activities of other compounds, especially insoluble natural compounds. Meanwhile, the successful development of OBB-ASDs could shed new light on the research process of poorly soluble medicine.

Amorphous calcium carbonate as a novel potential treatment for osteoarthritis in dogs: a pilot clinical study

Background

Amorphous calcium carbonate (ACC) is a potential new treatment for canine osteoarthritis (OA) with novel mechanisms based on local pH modulation and targeting bone remodeling, inflammation, and pain. The aim of this pilot exploratory clinical study was to obtain initial data on the potential efficacy and safety of ACC in OA dogs and to determine if further investigation was appropriate using similar assessment methods.

Materials and methods

In this prospective, randomized, double-blind, controlled pilot study, 41 client-owned dogs were allocated in a 2:1 ratio to ACC: placebo given orally for 56 days. Efficacy assessments included improvements in pain and mobility using owner questionnaires [Canine Brief Pain Inventory (CBPI), Client Specific Outcome Measure (CSOM), and Veterinary Orthopedic Scores (VOS)]. Safety in the study population was monitored by veterinary examinations, clinical pathology, and adverse events.

Results

Fifty-three dogs were screened, of which 41 enrolled and served for the safety assessment. Thirty-six dogs were found evaluable for initial efficacy assessment. Three dogs given placebo (21.4%) and one given ACC (4.5%) were removed before day 56 due to owner-perceived pain and were considered treatment failures. There were no serious adverse events or clinically significant treatment-related effects in the study. Overall, ACC was found safe in the small study population. On day 56, proportionally more ACC than placebo dogs were treatment successes based on CBPI (45.5% vs. 21.4%) and CSOM (63.6% vs. 30.8%, respectively); however, these differences were not statistically significant (p = 0.15 and 0.06, respectively). On day 56, within the ACC group but not the placebo group, the CBPI, CSOM, and VOS assessments were lower compared to day 0 and day 14 (p < 0.05).

Limitations

The relatively small number of dogs limited the statistical power of the pilot study in evaluating the efficacy and safety of ACC.

Conclusion

Study results support the conduct of larger, appropriately powered studies using similar assessments to confirm whether ACC may be a safe and effective treatment for OA in dogs.

Development and Optimization of Dipyridamole- and Roflumilast-Loaded Nanoemulsion and Nanoemulgel for Enhanced Skin Permeation: Formulation, Characterization, and In Vitro Assessment

This study explores developing and optimizing a nanoemulsion (NE) system loaded with dipyridamole and roflumilast, aiming to improve skin penetration and retention. The NE formulation was further transformed into a nanoemulgel to enhance its application as a topical treatment for psoriasis. Solubility studies were conducted to select the oil, surfactant, and co-surfactant. Phase diagrams were constructed using the aqueous phase titration method. All the formulations were in nanoscale, and Formula (F2) (which contains oleic acid oil as the oil phase, a mixture of Surfactant Tween 80 and co-surfactant (ethanol) at a ratio of 1:2 in addition to distilled water as an aqueous phase in a ratio of 1:5:4, respectively) was the selected formula depending on the particle size, PDI, and zeta potential. Formula (F2) has the best ratio because it gives the smallest nanoemulsion globule size (particle size average of 167.1 nm), the best homogenicity (lowest PDI of 0.195), and the highest stability (higher zeta potential of -32.22). The selected formula was converted into a nanoemulgel by the addition of 0.5% (w/w) xanthan gum (average particle size of 172.7 nm) and the best homogenicity (lowest PDI of 0.121%) and highest stability (higher zeta potential of -28.31). In conclusion, the selected formula has accepted physical and chemical properties, which enhanced skin penetration.

The interplay of poorly soluble drugs in dissolution from amorphous solid dispersions

In recent years, the application of fixed dose combinations of antiretroviral drugs in HIV therapy has been established. Despite numerous therapeutic benefits, this approach poses several challenges for the formulation development especially when poorly soluble drugs are considered. Amorphous solid dispersions (ASD) thereby have gained considerable interest in the pharmaceutical field, however, mainly including binary systems containing only one drug and a polymer. The co-formulation of two amorphous drugs can be accompanied by an immense increase in the complexity of the system as exemplarily reported for ritonavir and lopinavir embedded in a composite polymer matrix of PVPVA. The present study aims to present a new formulation approach to overcome the well-documented interaction during dissolution. Two different polymers, PVPVA and HPMCAS were used to produce ASDs for both drugs individually via hot-melt extrusion. The embedding of lopinavir in the slower dissolving polymer HPMCAS, while using PVPVA for ritonavir was found to significantly improve the overall dissolution performance compared to the individual use of PVPVA as well as to the commercial product Kaletra®. In addition, the use of different grades of HPMCAS demonstrated the possibility to further modify the dissolution profile. For a preliminary biorelevant assessment, the selected formulations were tested in a biphasic dissolution setup.

Sweeteners Show a Plasticizing Effect on PVP K30-A Solution for the Hot-Melt Extrusion of Fixed-Dose Amorphous Curcumin-Hesperetin Solid Dispersions

The co-administration of curcumin and hesperetin might be beneficial in terms of neuroprotective activity; therefore, in this study, we attempted to develop a fixed-dose formulation comprising these two compounds in an amorphous state. The aim of obtaining an amorphous state was to overcome the limitations of the low solubility of the active compounds. First, we assessed the possibility of using popular sweeteners (erythritol, xylitol, and sorbitol) as plasticizers to reduce the glass transition temperature of PVP K30 to prepare the polymer-excipient blends, which allowed the preparation of amorphous solid dispersions via hot-melt extrusion at a temperature below the original glass transition of PVP K30. Erythritol proved to be the superior plasticizer. Then, we focused on the development of fixed-dose amorphous solid dispersions of curcumin and hesperetin. Powder X-ray diffraction and thermal analysis confirmed the amorphous character of dispersions, whereas infrared spectroscopy helped to assess the presence of intermolecular interactions. The amorphous state of the produced dispersions was maintained for 6 months, as shown in a stability study. Pharmaceutical parameters such as dissolution rate, solubility, and in vitro permeability through artificial membranes were evaluated. The best improvement in these features was noted for the dispersion, which contained 15% of the total content of the active compounds with erythritol used as the plasticizer.

Integrative Salt Selection and Formulation Optimization: Perspectives of Disproportionation and Microenvironmental pH Modulation

We report a novel utilization of a pH modifier as a disproportionation retardant in a tablet formulation. The drug molecule of interest has significant bioavailability challenges that require solubility enhancement. In addition to limited salt/cocrystal options, disproportionation of the potential salt(s) was identified as a substantial risk. Using a combination of Raman spectroscopy with chemometrics and quantitative X-ray diffraction in specially designed stress testing, we investigated the disproportionation phenomena. The learnings and insight drawn from crystallography drove the selection of the maleate form as the target API. Inspired by the fumarate form's unique stability and solubility characteristics, we used fumaric acid as the microenvironmental pH modulator. Proof-of-concept experiments with high-risk (HCl) and moderate-risk (maleate) scenarios confirmed the synergistic advantage of fumaric acid, which interacts with the freebase released by disproportionation to form a more soluble species. The resultant hemifumarate helps maintain the solubility at an elevated level. This work demonstrates an innovative technique to mediate the solubility drop during the "parachute" phase of drug absorption using compendial excipients, and this approach can potentially serve as an effective risk-mitigating strategy for salt disproportionation.

Shifting the Focus from Dissolution to Permeation: Introducing the Meso-fluidic Chip for Permeability Assessment (MCPA)

In response to the growing ethical and environmental concerns associated with animal testing, numerous in vitro tools of varying complexity and biorelevance have been developed and adopted in pharmaceutical research and development. In this work, we present one of these tools, i.e., the Meso-fluidic Chip for Permeability Assessment (MCPA), for the first time. The MCPA combines an artificial barrier (PermeaPad®) with an organ-on-chip device (MIVO®) and real-time automated concentration measurements, to yield a sustainable, yet effortless method for permeation testing. The system offers three major physiological aspects, i.e., a biomimetic membrane, an optimal membrane interfacial area-to-donor-volume-ratio (A/V) and a physiological flow on the acceptor/basolateral side, which makes the MPCA an ideal candidate for mechanistic studies and excellent in vivo bioavailability predictions. We validated the method with a handful of assorted drug compounds in unstirred and stirred donor conditions, before exploring its applicability as a tool for dissolution/permeation testing on a BCS class III/I drug (pyrazinamide) crystalline adducts and BCS class II/IV (hydrocortisone) amorphous solid dispersions. The results were highly reproducible and clearly displayed the method's potential for evaluating the performance of enabling formulations, and possibly even predicting in vivo performance. We believe that, upon further development, the MCPA will serve as a useful in vitro tool that could push sustainability into pharmaceutics by refining, reducing and replacing animal testing in early-stage drug development.

Insights into the Mechanism of Enhanced Dissolution in Solid Crystalline Formulations

Solid dispersions are a promising approach to enhance the dissolution of poorly water-soluble drugs. Solid crystalline formulations show a fast drug dissolution and a high thermodynamic stability. To understand the mechanisms leading to the faster dissolution of solid crystalline formulations, physical mixtures of the poorly soluble drugs celecoxib, naproxen and phenytoin were investigated in the flow through cell (apparatus 4). The effect of drug load, hydrodynamics in the flow through cell and particle size reduction in co-milled physical mixtures were studied. A carrier- and drug-enabled dissolution could be distinguished. Below a certain drug load, the limit of drug load, carrier-enabled dissolution occurred, and above this value, the drug defined the dissolution rate. For a carrier-enabled behavior, the dissolution kinetics can be divided into a first fast phase, a second slow phase and a transition phase in between. This study contributes to the understanding of the dissolution mechanism in solid crystalline formulations and is thereby valuable for the process and formulation development.

Development and performance evaluation of self-assembled pH-responsive curcumin-bacterial exopolysaccharide micellar conjugates as bioactive delivery system

The present study reports the synthesis of micellar conjugates, wherein curcumin (Cur), a bioactive compound with poor bioavailability, was covalently bonded to a bacterial exopolysaccharide (EPS). These conjugates were synthesized by utilizing succinic acid that linked Cur to the pyranosyl moiety of the EPS. The Cur-EPS conjugates appeared as spherical micelles in aqueous solution and were found to have an average hydrodynamic diameter of 254 ± 2.7 nm. The micellar conjugates showed superior stability than Cur as evident from their negative surface charge (-27 ± 1.8 mV) and low polydispersity index (PDI) (0.33 ± 0.04). The in vitro studies on release kinetics helped elucidate the pH-responsive characteristics of the Cur-EPS conjugate, as 87.50 ± 1.45 % of Cur was released at an acidic pH of 5.6, in contrast to 30.15 ± 2.61 % at systemic pH of 7.4 at 150 h. The conjugates were hemocompatible and exhibited cytotoxic effect against the osteosarcoma cell line (MG-63) after 48 h treatment. They also demonstrated superior antibacterial, antibiofilm, and antioxidant activities in comparison to free Cur. Therefore, the Cur-EPS conjugates have potential pharmaceutical applications as therapeutic biomaterial that can be applied as a drug delivery system.

Morphological Control of Crystalline Savolitinib via the Volatile Deep Eutectic Solvent Technique

Savolitinib is a compound that can crystallize in an undesirable, high aspect ratio needle morphology. This morphology type may cause issues in downstream processing. This paper demonstrates a unique method to alter the crystal morphology of savolitinib to make it more processable, resulting in the active pharmaceutical ingredient (API) crystallizing out in considerably more processable stellates. The volatile deep eutectic solvent technique presents a simple and scalable method for changing the crystal morphology while maintaining the polymorph of the API in this case, confirmed via powder X-ray diffraction and differential scanning calorimetry analysis.

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

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

ASDs of PROTACs: Spray-dried solid dispersions as enabling formulations

Proteolysis targeting chimeras (PROTACs) are a promising class of pharmaceutical agents with a unique mode of action. PROTACs enable the targeting of a broad variety of structures including transcription factors and other "undruggable" targets. The poor solubility and slow dissolution of PROTACs currently limit the extensive use of their potential. Up to date, only very limited drug delivery options have been examined to address this challenge. Therefore, we explored the potential of amorphous solid dispersions (ASDs) by spray drying a model PROTAC with different polymers. The resulting formulations were assessed in terms of purity, solid state, dissolution performance, and stability. A strong increase in supersaturation compared to the physical mixture was provided, although in both systems the PROTAC molecule itself was already in the amorphous state. Evaluation of the reasons for the superiority of the ASD formulations revealed that the major factor was the homogeneous, molecular distribution of the active pharmaceutical ingredient (API) in the polymer matrix, as well as improved wettability of the formulation containing Soluplus compared to the physical mixture. The manufactured formulations were stable over a minimum of 8 weeks when protected from light and humidity.

Mucoadhesive Carrier-Mediated Oral Co-delivery of Bcl2 Inhibitors Improves Gastric Cancer Treatment

Gastric cancer treatment is challenging due to the lack of early-stage diagnostic technology and targeted delivery systems. Currently, the available treatments for gastric cancer are surgery, chemotherapy, immunotherapy, and radiation. These strategies are either invasive or require systemic delivery, exerting toxicities within healthy tissues. By creation of a targeted delivery system to the stomach, gastric cancer can be treated in the early stages. Such an approach reduces the negative effects on the rest of the body by minimizing systemic absorbance and random localization. With this in mind, we developed a mucoadhesive vehicle composed of β-Glucan And Docosahexaenoic Acid (GADA) for controlled drug/gene delivery. In the current study, we investigated the therapeutic effect of codelivery Bcl2 inhibitors navitoclax (NAVI) and siRNA (Bcl2) via oral using GADA. The therapeutic efficacy of the GADA-mediated oral NAVI/siRNA was investigated in a gastric cancer mouse model. Higher Bcl2 inhibition efficacy was observed in Western blotting and TUNEL assay in mice treated with GADA/NAVI/siRNA compared to free NAVI, siRNA, and NAVI/siRNA. Histology (H&E) and immunohistochemistry (Ki67, TUNEL, and BCl2) analyses confirmed a significant reduction of the tumor region. Interaction between GADA and mucus resulted in retention for over 6 h and thereby sustained local payload release. The developed oral carrier GADA is an emerging vehicle that has promising potential in oral delivery of both small and large molecules, and their mucoadhesive property results in improved therapeutic efficacy with minimal side effects compared to conventional treatment. This study opens a new window for the effective delivery of oral medicine for the treatment of gastric cancer and other gastrointestinal diseases.

Overcoming drug impurity challenges in amorphous solid dispersion with rational development of biorelevant dissolution-permeation method

Hot-melt extrusion is often used to prepare amorphous solid dispersion to overcome low drug solubility and enhance bio-performance of the formulation. Due to the uniqueness of each drug - polymer combination and its physico-chemical properties, setting the appropriate HME barrel temperature, feed rate and screw speed ensures drug amorphization, absence of residual crystallinity, absence of water, and a suitable drug release profile. In this research, samples with BCS II/IV model drug and PVP/VA polymer were prepared to evaluate the impact of HME process parameters, incoming drug form (anhydrous vs. hydrate), and drug supplier (i.e., impurity profile), on biorelevant drug release. This study provides a relationship between observed in vitro supersaturation and precipitation behavior of amorphous solid dispersion formulation with in vivo results, on patients, by using the acceptor profile of side-by-side dissolution-permeation apparatus. An in vitro dissolution method, in small volumes, in an apparatus with paddles and dissolution-permeation side-by-side method was developed on the MicroFlux™ apparatus to assess if the differences observed in vitro bears relevance to the bioequivalence outcome in vivo. The former was used to guide the generic drug product development due to high discriminatory strength, while the latter was biorelevant, due to the inclusion of the second compartment assuring absorptive environment to capture the impact of supersaturation and subsequent precipitation on bioavailability. Bio-relevancy of the in vitro method was confirmed with the in vivo dog study and clinical study on patients, and an in vitro - in vivo correlation was established. For the investigated BCS II/IV drug, this research highlights the importance of considering supersaturation and formation of colloidal species during amorphous solid dispersion release testing to assure product quality, safety and efficacy.

Scope and Application of Hot Melt Extrusion in the Development of Controlled and Sustained Release Drug Delivery Systems

Controlled-release drug delivery systems (CRDDS) are more beneficial than conventional immediate release (IRDDS) for reduced intake, prolonged duration of action, lesser adverse effects, higher bioavailability, etc. The preparation of CRDDS is more complex than IRDDS. The hot melt extrusion (HME) technique is used for developing amorphous solid dispersion of poorly water soluble drugs to improve their dissolution rate and oral bioavailability. HME can be employed to develop CRDDS. Sustained release delivery systems (SRDDS), usually given orally, can also be developed using HME. This technique has the advantages of using no organic solvent, converting crystalline drugs to amorphous, improving bioavailability, etc. However, the heat sensitivity of drugs, miscibility between drug-polymer, and the availability of a few polymers are some of the challenges HME faces in developing CRDDS and SRDDS. The selection of a suitable polymer and the optimization of the process with the help of the QbD principle are two important aspects of the successful application of HME. In this review, strategies to prepare SRDDS and CRDDS using HME are discussed with its applications in research.

Solid-state analysis for pharmaceuticals: Pathways to feasible and meaningful analysis

The solid state of matter is the preferred starting point for designing a pharmaceutical product. This is driven by both patient preferences and the relative ease of supplying a solid pharmaceutical product with desired quality and performance. Solid form diversity is increasingly prevalent as a crucial element in designing these products, which underpins the importance of solid-state analytical methods. This paper provides a critical analysis of challenges related to solid-state analytics, as well as considerations and suggestions for feasible and meaningful pharmaceutical analysis.

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

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

Composition Dependency of the Flory-Huggins Interaction Parameter in Drug-Polymer Phase Behavior

An innovative strategy to address recent challenges in the oral administration of poorly soluble drugs is the formulation of amorphous solid dispersions (ASDs), where the drug is dissolved in a highly soluble carrier polymer. Therefore, special knowledge of the drug-polymer phase behavior is essential for an effective product and process design, accelerating the introduction of novel efficacious ASD products. Flory-Huggins theory can be applied to model solubility temperatures of crystalline drugs in carrier polymers over the drug fraction. However, predicted solubility temperatures lack accuracy in cases of strong drug/polymer interactions that are not represented in the Flory-Huggins lattice model. Within this study, a modeling strategy is proposed to improve the predictive power through an extension of the Flory-Huggins interaction parameter by a correlation with the drug fraction. Therefore, the composition dependency of the Flory-Huggins interaction parameter was evaluated experimentally for various drug-polymer formulations that cover a wide variety of drug and polymer characteristics regarding molecular weights, glass transition temperatures and melting temperatures, as well as drug-polymer interactions of different strengths and effects. The extended model was successfully approved for nine exemplary ASD formulations containing the drugs acetaminophen, itraconazole, and griseofulvine, as well as the following polymers: basic butylated methacrylate copolymer, Soluplus®, and vinylpyrrolidone/vinyl acetate copolymer. A high correlation between the predicted solubility temperatures and experimental and literature data was found, particularly at low drug fractions, since the model accounts for composition dependent drug-polymer interactions.