Effect of supersaturation on the oral bioavailability of paclitaxel/polymer amorphous solid dispersion

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.

Kinetic and Thermodynamic Interplay of Polymer-Mediated Liquid-Liquid Phase Separation for Poorly Water-Soluble Drugs

Understanding the interplay between kinetics and thermodynamics of polymer-mediated liquid-liquid phase separation is crucial for designing and implementing an amorphous solid dispersion formulation strategy for poorly water-soluble drugs. This work investigates the phase behaviors of a poorly water-soluble model drug, celecoxib (CXB), in a supersaturated aqueous solution with and without polymeric additives (PVP, PVPVA, HPMCAS, and HPMCP). Drug-polymer-water ternary phase diagrams were also constructed to estimate the thermodynamic behaviors of the mixtures at room temperature. The liquid-liquid phase separation onset point for CXB was detected using an inline UV/vis spectrometer equipped with a fiber optic probe. Varying CXB concentrations were achieved using an accurate syringe pump throughout this study. The appearance of the transient nanodroplets was verified by cryo-EM and total internal reflection fluoresence microscopic techniques. The impacts of various factors, such as polymer composition, drug stock solution pumping rates, and the types of drug-polymer interactions, are tested against the onset points of the CXB liquid-liquid phase separation (LLPS). It was found that the types of drug-polymer interactions, i.e., hydrogen bonding and hydrophobic interactions, are vital to the position and shapes of LLPS in the supersaturation drug solution. A relation between the behaviors of LLPS and its location in the CXB-polymer-water ternary phase diagram was drawn from the findings.

Co-release of paclitaxel and encequidar from amorphous solid dispersions increase oral paclitaxel bioavailability in rats

The oral bioavailability of paclitaxel is limited due to low solubility and high affinity for the P-glycoprotein (P-gp) efflux transporter. Here we hypothesized that maximizing the intestinal paclitaxel levels through apparent solubility enhancement and controlling thesimultaneous release of both paclitaxel and the P-gp inhibitor encequidar from amorphous solid dispersions (ASDs) would increase the oral bioavailability of paclitaxel. ASDs of paclitaxel and encequidar in polyvinylpyrrolidone K30 (PVP-K30), hydroxypropylmethylcellulose 5 (HPMC-5), and hydroxypropylmethylcellulose 4 K (HPMC-4K) were hence prepared by freeze-drying. In vitro dissolution studies showed that both compounds were released fastest from PVP-K30, then from HPMC-5, and slowest from HPMC-4K ASDs. The dissolution of paclitaxel from all polymers resulted in stable concentration levels above the apparent solubility. The pharmacokinetics of paclitaxel after oral administration to male Sprague-Dawley rats was investigated with or without 1 mg/kg encequidar, as amorphous solids or polymer-based ASDs. The bioavailability of paclitaxel increased 3- to 4-fold when administered as polymer-based ASDs relative to solid amorphous paclitaxel. However, when amorphous paclitaxel was co-administered with encequidar, either as an amorphous powder or as a polymer-based ASD, the bioavailability increased 2- to 4-fold, respectively. Interestingly, a noticeable increase in paclitaxel bioavailability of 24-fold was observed when paclitaxel and encequidar were co-administered as HPMC-5-based ASDs. We, therefore, suggest that controlling the dissolution rate of paclitaxel and encequidar in order to obtain simultaneous and timed release from polymer-based ASDs is a strategy to increase oral paclitaxel bioavailability.

Evaluation of microstructure, dissolution rate, and oral bioavailability of paclitaxel poloxamer 188 solid dispersion

Poor solubility is a major challenge for enhancing the oral bioavailability and clinical application of many drugs, including the broad-spectrum chemotherapy drug paclitaxel (PTX). A practical approach to improving the solubility of insoluble drugs is through the use of solid dispersion (SD). This study aimed to investigate the potential of the triblock copolymer, poloxamer 188 (P188), as a carrier for preparing solid dispersion of paclitaxel using spray drying technology. We systematically studied its microstructure, dissolution behavior in vitro, and pharmacokinetics. Our findings demonstrate that PTX exists in an amorphous state in copolymer composed of polyoxyethylene-polyoxypropylene-polyoxyethylene (PEO-PPO-PEO) P188, with stronger miscibility with hydrophobic PPO segments. All three in vitro dissolution models revealed that the release rate of drugs in SD was significantly higher compared to that of physical mixtures (PM) as well as raw drugs. Furthermore, our pharmacokinetic results showed that the area under the curve(AUC) of PTX in SD was 6 times higher than that of active pharmaceutical ingredient(API), 4.5 times higher than PM, and the highest blood drug concentration (Cmax) reached 357.51 ± 125.54 (ng/mL), approximately 20 times higher than API. Overall, our findings demonstrate that the dissolution rate of amorphous PTX in SD significantly improves, effectively enhancing the oral bioavailability of PTX.

Stability Challenges of Amorphous Solid Dispersions of Drugs: A Critical Review on Mechanistic Aspects

The most common drawback of the existing and novel drug molecules is their low bioavailability because of their low solubility. One of the most important approaches to enhance the bioavailability in the enteral route for poorly hydrophilic molecules is amorphous solid dispersion (ASD). The solubility of compounds in amorphous form is comparatively high because of the availability of free energy produced during formulation. This free energy results in the change of crystalline nature of the prepared ASD to the stable crystalline form leading to the reduced solubility of the product. Due to the intrinsic chemical and physical uncertainty and the restricted knowledge about the interactions of active molecules with the carriers making, this ASD is a challenging task. This review focused on strategies to stabilize ASD by considering the various theories explaining the free-energy concept, physical interactions, and thermal properties. This review also highlighted molecular modeling and machine learning computational advancement to stabilize ASD.

Comparative analysis of drug-salt-polymer interactions by experiment and molecular simulation improves biopharmaceutical performance

The propensity of poorly water-soluble drugs to aggregate at supersaturation impedes their bioavailability. Supersaturated amorphous drug-salt-polymer systems provide an emergent approach to this problem. However, the effects of polymers on drug-drug interactions in aqueous phase are largely unexplored and it is unclear how to choose an optimal salt-polymer combination for a particular drug. Here, we describe a comparative experimental and computational characterization of amorphous solid dispersions containing the drug celecoxib, and a polymer, polyvinylpyrrolidone vinyl acetate (PVP-VA) or hydroxypropyl methylcellulose acetate succinate, with or without Na+/K+ salts. Classical models for drug-polymer interactions fail to identify the best drug-salt-polymer combination. In contrast, more stable drug-polymer interaction energies computed from molecular dynamics simulations correlate with prolonged stability of supersaturated amorphous drug-salt-polymer systems, along with better dissolution and pharmacokinetic profiles. The celecoxib-salt-PVP-VA formulations exhibit excellent biopharmaceutical performance, offering the prospect of a low-dosage regimen for this widely used anti-inflammatory, thereby increasing cost-effectiveness, and reducing side-effects.

Supersaturation and Precipitation Applicated in Drug Delivery Systems: Development Strategies and Evaluation Approaches

Supersaturation is a promising strategy to improve gastrointestinal absorption of poorly water-soluble drugs. Supersaturation is a metastable state and therefore dissolved drugs often quickly precipitate again. Precipitation inhibitors can prolong the metastable state. Supersaturating drug delivery systems (SDDS) are commonly formulated with precipitation inhibitors, hence the supersaturation is effectively prolonged for absorption, leading to improved bioavailability. This review summarizes the theory of and systemic insight into supersaturation, with the emphasis on biopharmaceutical aspects. Supersaturation research has developed from the generation of supersaturation (pH-shift, prodrug and SDDS) and the inhibition of precipitation (the mechanism of precipitation, the character of precipitation inhibitors and screening precipitation inhibitors). Then, the evaluation approaches to SDDS are discussed, including in vitro, in vivo and in silico studies and in vitro-in vivo correlations. In vitro aspects involve biorelevant medium, biomimetic apparatus and characterization instruments; in vivo aspects involve oral absorption, intestinal perfusion and intestinal content aspiration and in silico aspects involve molecular dynamics simulation and pharmacokinetic simulation. More physiological data of in vitro studies should be taken into account to simulate the in vivo environment. The supersaturation theory should be further completed, especially with regard to physiological conditions.

Supersaturation and phase behavior during dissolution of amorphous solid dispersions

Amorphous solid dispersion (ASD) is a promising strategy to enhance solubility and bioavailability of poorly water-soluble drugs. Due to higher free energy of ASD, supersaturated drug solution could be generated during dissolution. When amorphous solubility of a drug is exceeded, drug-rich nanodroplets could form and act as a reservoir to maintain the maximum free drug concentration in solution, facilitating the absorption of the drug in vivo. Dissolution behavior of ASD has received increasing interests. This review will focus on the recent advances in ASD dissolution, including the generation and maintenance of supersaturated drug solution in absence or presence of liquid-liquid phase separation. Mechanism of drug release from ASD including polymer-controlled dissolution and drug-controlled dissolution will be introduced. Formation of amorphous drug-rich nanodroplets during dissolution and the underlying mechanism will be discussed. Phase separation morphology of hydrated ASD plays a critical role in dissolution behavior of ASD, which will be highlighted. Supersaturated drug solution shows poor physical stability and tends to crystallize. The effect of polymer and surfactant on supersaturated drug solution will be demonstrated and some unexpected results will be shown. Physicochemical properties of drug and polymer could impact ASD dissolution and some of them even show opposite effect on dissolution and physical stability of ASD in solid state, respectively. This review will contribute to a better understanding of ASD dissolution and facilitate a rational design of ASD formulation.

Hydroxypropyl methylcellulose acetate succinate as an exceptional polymer for amorphous solid dispersion formulations: A review from bench to clinic

Amorphous solid dispersions (ASDs) are a proven system for achieving a supersaturated state of drug, in which the concentration of drug is greater than its crystalline solubility. The usage of Hydroxypropyl Methylcellulose Acetate Succinate (HPMCAS) in the development of ASDs has grown significantly, as evidenced by the fact that majority of commercially approved ASD formulations are based on HPMCAS. HPMCAS has been widely utilized as a solubility enhancer and precipitation inhibitor or stabilizer to achieve supersaturation and inhibit crystallization of drugs in the gastrointestinal tract. The characteristics of HPMCAS ASDs such as less hygroscopic, strong drug-polymer hydrophobic interactions, high solubilization efficiency, greater potential to generate, maintain drug supersaturation and crystallization inhibition outperform other polymeric carriers in ASD development. Furthermore, combining HPMCAS with other polymers or surfactants as ternary ASDs could be a viable approach for enhancing oral absorption of poorly soluble drugs. This review discusses the concepts of supersaturation maintenance or precipitation inhibition of HPMCAS in the ASD formulations. In addition, the mechanisms underlying for improved dissolution performance, oral bioavailability and stability of HPMCAS ASDs are explored.

Hot-melt extruded hydroxypropyl methylcellulose acetate succinate based amorphous solid dispersions: Impact of polymeric combinations on supersaturation kinetics and dissolution performance

Nucleation inhibition and maintenance of drug supersaturation over a prolonged period are desirable for improving oral absorption of amorphous solid dispersions. The present study investigates the impact of binary and ternary amorphous solid dispersions on the supersaturation kinetics of nifedipine using the polymers hydroxypropylmethylcellulose acetate succinate (HPMCAS) LG, and HG, Eudragit® RSPO, Eudragit® FS100, Kollidon® VA64 and Plasdone™ K-29/32. The amorphous solubility, nucleation induction time, and particle size analysis of nifedipine in a supersaturated solution were performed with and without the presence of polymers, alone or in combination. The HPMCAS-HG and HPMCAS-HG + LG combinations showed the highest nifedipine amorphous solubility of 169.47, 149.151 µg/mL, respectively and delay in nucleation induction time up to 120 min compared to other polymeric combinations. The solid dispersions prepared via hot melt extrusion showed the transformation of crystalline nifedipine to amorphous form. The in-vitro non-sink dissolution study revealed that although the binary nifedipine/HPMCAS-LG system had shown the greater supersaturation concentration of 66.1 µg/mL but could not maintain a supersaturation level up to 360 min. A synergistic effect emerged for ternary nifedipine/HPMCAS-LG/HPMCAS-HG, and nifedipine/HPMCAS-LG/Eudragit®FS100 systems maintained the supersaturation level with enhanced dissolution performance, demonstrating the potential of polymeric combinations for improved amorphous solid dispersion performance.

Pharmaceutical profiling and molecular dynamics simulations reveal crystallization effects in amorphous formulations

Robust and reliable in vivo performance of medicines based on amorphous solid dispersions (ASDs) depend on maintenance of physical stability and efficient supersaturation. However, molecular drivers of these two kinetic processes are poorly understood. Here we used molecular dynamics (MD) simulations coupled with experimental assessments to explore supersaturation, nucleation, and crystal growth. The effect of drug loading on physical stability and supersaturation potential was highly drug specific. Storage under humid conditions influenced crystallization, but also resulted in morphological changes and particle fusion. This led to increased particle size, which significantly reduced dissolution rate. MD simulations identified the importance of nano-compartmentalization in the crystallization rate of the ASDs. Nucleation during storage did not inherently compromise the ASD. Rather, the poorer performance resulted from a combination of properties of the compound, nanostructures formed in the formulation, and crystallization.

In Vitro-In Vivo Correlation in Cocrystal Dissolution: Consideration of Drug Release Profiles Based on Coformer Dissolution and Absorption Behavior

This study assessed the in vitro-in vivo correlation in cocrystal dissolution based on the coformer behavior. 4-Aminobenzoic acid (4ABA) was used as a coformer. Cocrystals of poorly water-soluble drugs with 4ABA, ketoconazole cocrystal (KTZ-4ABA), posaconazole cocrystal (PSZ-4ABA), and itraconazole cocrystal (ITZ-4ABA) were used. These three cocrystals generated supersaturated solutions in fasted state simulated intestinal fluid (FaSSIF) in a small-scale, 8 mL dissolution vessel. The time profile of the dissolved amount of 4ABA, an indicator of cocrystal dissolution, was significantly different among the three cocrystals. Under the conditions utilized, half of the KTZ-4ABA cocrystal solid rapidly dissolved within 5 min and the dissolved amount (% of applied amount) of KTZ and 4ABA was the same. Then, even though the residual solid cocrystal gradually dissolved, KTZ precipitated with time. The PSZ-4ABA cocrystal dissolved in a linear fashion with time but the dissolved concentration of PSZ reached a plateau in the supersaturated state and was maintained for at least 2 h. The dissolution rate of ITZ-4ABA was very slow compared to those of the other cocrystals, but a similar tendency was observed between cocrystal dissolution and the dissolved amount of ITZ. The rank order of the cocrystal dissolution rate based on the conformer concentration was KTZ-4ABA > PSZ-4ABA > ITZ-4ABA. Furthermore, cocrystallization of the three drugs with 4ABA significantly enhanced the oral drug absorption in rats. The rank order of the in vivo cocrystal dissolution rate by a deconvolution analysis with the plasma concentration-time profile of 4ABA was KTZ-4ABA > PSZ-4ABA > ITZ-4ABA, which corresponded well with the in vitro dissolution profiles of the cocrystals. These results indicate that analysis of cocrystal dissolution based on the coformer behavior may be useful to evaluate the in vitro and in vivo cocrystal dissolution.

Impact of co-administered stabilizers on the biopharmaceutical performance of regorafenib amorphous solid dispersions

Poor solubility of drug candidates is a well-known and thoroughly studied challenge in the development of oral dosage forms. One important approach to tackle this challenge is the formulation as an amorphous solid dispersion (ASD). To reach the desired biopharmaceutical improvement a high supersaturation has to be reached quickly and then be conserved long enough for absorption to take place. In the presented study, various formulations of regorafenib have been produced and characterized in biorelevant in-vitro experiments. Povidone-based formulations, which are equivalent to the marketed product Stivarga®, showed a fast drug release but limited stability and robustness after that. In contrast, HPMCAS-based formulations exhibited excellent stability of the supersaturated solution, but unacceptably slow drug release. The attempt to combine the desired attributes of both formulations by producing a ternary ASD failed. Only co-administration of HPMCAS as an external stabilizer to the rapidly releasing Povidone-based ASDs led to the desired dissolution profile and high robustness. This optimized formulation was tested in a pharmacokinetic animal model using Wistar rats. Despite the promising in-vitro results, the new formulation did not perform better in the animal model. No differences in AUC could be detected when compared to the conventional (marketed) formulation. These data represent to first in-vivo study of the new concept of external stabilization of ASDs. Subsequent in-vitro studies revealed that temporary exposure of the ASD to gastric medium had a significant and long-lasting effect on the dissolution performance and externally administered stabilizer could not prevent this sufficiently. By applying the co-administered HPMCAS as an enteric coating onto Stivarga tablets, a new bi-functional approach was realized. This approach achieved the desired tailoring of the dissolution profile and high robustness against gastric medium as well as against seeding.

Current strategies for oral delivery of BCS IV drug nanocrystals: challenges, solutions and future trends

INTRODUCTION

Oral absorption of BCS IV drug benefits little from improved dissolution. Therefore, the absorption of BCS IV drug nanocrystals 'as a whole' strategy is preferred, and structural modification of nanocrystals is required. Surface modification helps the nanocrystals maintain particle structure before drug dissolution is needed, thus enhancing the oral absorption of BCS IV drugs and promoting therapeutic effect. Here, the main challenges and solutions of oral BCS IV drug nanocrystals delivery are discussed. Moreover, strategies for nanocrystal surface modification that facilitates oral bioavailability of BCS IV drugs are highlighted, and provide insights for the innovation in oral drug delivery.

AREAS COVERED

Promising size, shape, and surface modification of nanocrystals have gained interests for application in oral BCS IV drugs.

EXPERT OPINION

Nanocrystal surface modification is a feasible method to maintain the structural integrity of nanocrystals, and the introduced materials can also be modified to integrate additional functions to further facilitate the absorption of nanocrystals. It is expected that the absorption 'as a whole' strategy of nanocrystals will provide different choices for the oral BCS IV drugs.

Surfactant-free amorphous solid dispersion with high dissolution for bioavailability enhancement of hydrophobic drugs: a case of quercetin

At present, saccharides as hydrophilic matrixes, have been gradually used in amorphous solid dispersions (ASD) for dispersing poorly water-soluble drugs without surfactants. In this study, an amorphous chitosan oligosaccharide (COS) was applied as a water-soluble matrix to form surfactant-free ASD via the ball milling to vitrify quercetin (QUE) and enhance the dissolution and bioavailability. Solid-state characterization (DSC, XRPD, FTIR, SEM and PLM) and physical stability assessments verified that the prepared ASDs showed excellent physical stability with complete amorphization due to potential interactions between QUE and COS. In vitro sink dissolution tests suggested all QUE-COS ASDs (w:w, 1:1, 1:2 and 1:4) significantly enhanced the dissolution rate of QUE. Meanwhile, in vitro non-sink dissolution exhibited that the maximum supersaturated concentration ranged from 112.62 to 138.00 µg/mL for all QUE-COS ASDs, which was much higher than that of pure QUE. Besides, the supersaturation of QUE-COS ASD kept for at least 24 h. In rat pharmacokinetics, the oral bioavailability of QUE-COS ASDs showed 1.64 ∼ 2.25 times increase compared to the pure QUE (p < .01). Hence, the present study confirms the amorphous COS could be applied as a promising hydrophilic matrix in QUE-COS ASDs for enhancing dissolution performance and bioavailability of QUE.

Mechanisms of increased bioavailability through amorphous solid dispersions: a review

Amorphous solid dispersions (ASDs) can increase the oral bioavailability of poorly soluble drugs. However, their use in drug development is comparably rare due to a lack of basic understanding of mechanisms governing drug liberation and absorption in vivo. Furthermore, the lack of a unified nomenclature hampers the interpretation and classification of research data. In this review, we therefore summarize and conceptualize mechanisms covering the dissolution of ASDs, formation of supersaturated ASD solutions, factors responsible for solution stabilization, drug uptake from ASD solutions, and drug distribution within these complex systems as well as effects of excipients. Furthermore, we discuss the importance of these findings on the development of ASDs. This improved overall understanding of these mechanisms will facilitate a rational ASD formulation development and will serve as a basis for further mechanistic research on drug delivery by ASDs.

Amorphous solid dispersion of nisoldipine by solvent evaporation technique: preparation, characterization, in vitro, in vivo evaluation, and scale up feasibility study

The present study was designed to determine the applicability of a newly derived dimensionless number precipitation parameter, "supersaturation holding capacity (SHC)" in development of amorphous solid dispersion (ASD) of a rapidly crystallizing drug, nisoldipine. Also, ASD preparation from lab scale formulation technique to scalable spray drying technique followed by oral bioavailability study was demonstrated. Solution state screening of polymers was performed by determining nucleation induction time (tin) and SHC. With screened polymers, lab scale ASDs of nisoldipine were prepared using rotary evaporation (solvent evaporation) method, and the optimized stable ASDs were scaled up by spray drying. The ASDs were characterized by DSC, PXRD, and FTIR for amorphous nature and evaluated for apparent solubility, dissolution, and solid-state stability improvement. The spray dried ASDs were additionally evaluated for micrometric properties and oral bioavailability study.PVP grades demonstrated superior crystal growth inhibition properties (with 2-4-fold enhancements in SHC). ASDs prepared by both lab scale and scale-up technique using PVP stabilized the amorphous nisoldipine via antiplasticization effect that maintained the stability under accelerated stability conditions (40 °C/75% RH) for 6 months. Additionally, FTIR study confirmed the role of intermolecular interactions in amorphous state stabilization of PVP-based solid dispersions. PVP-based spray dried ASDs improved the apparent solubility 4-fold for PVP K17 and more than 3-fold for remaining spray dried ASDs. The enhanced solubility was translated to improved dissolution of the drug when compared with crystalline and amorphous form complementing the outcome of the solution state study. The spray dried ASD showed 2.3 and > 3-fold the improvement in Cmax and AUC (0-24 h) respectively when compared with crystalline nisoldipine during oral bioavailability study which highlights the significance of SHC parameter of polymers. The spray dried ASD has shown improved micromeritics properties then crystalline nisoldipine in terms of flow behavior.This unique study provides a rational strategy for selection of appropriate polymer in development of ASDs that can tackle both precipitation during dissolution and amorphous state stabilization in solid state and also considers the SHC in scale-up study. Graphical abstract.

Mechanistic insights into effect of surfactants on oral bioavailability of amorphous solid dispersions

Drug delivery of poorly soluble drugs in form amorphous solid dispersions (ASDs) is an appealing method to increase in vivo bioavailability. For rational formulation design, a mechanistic understanding of the impact of surfactants on the performance of ASD-based formulations is therefore of importance. In this study, we used hot-melt extrusion to prepare ASDs composed of the model drug substance efavirenz with hydroxypropyl methylcellulose phthalate (HPMCP) as the base polymer, and surfactants. Molecular dynamics simulations and in vitro dissolution studies were used to investigate formation and drug release from polymer vesicles, and their ability to maintain a supersaturation state as a function of surfactant composition. It was possible to identify main factors regulating particle formation and to modify dissolution profiles with different excipient compositions. Animal studies in the rat, in combination with physiologically based pharmacokinetic modeling, demonstrated enhanced drug absorption from formed vesicles. The surfactant composition in the ASD had a direct influence on the morphology of these vesicles, as well as kinetics of drug release, and, therefore, the oral bioavailability. ASDs, prepared by hot-melt extrusion method, were optimized for dissolution and adsorption rates increase. Our findings contribute to a better understanding of dissolution behavior of ASDs with respect to the function of surfactants, aiming to facilitate a rational formulation development and an accelerated transition from in vitro systems to in vivo applications.

Harnessing the therapeutic potential of anticancer drugs through amorphous solid dispersions

The treatment of cancer is still a major challenge. But tremendous progress in anticancer drug discovery and development has occurred in the last few decades. However, this progress has resulted in few effective oncology products due to challenges associated with anticancer drug delivery. Oral administration is the most preferred route for anticancer drug delivery, but the majority of anticancer drugs currently in product pipelines and the majority of those that have been commercially approved have inherently poor water solubility, and this cannot be mitigated without compromising their potency and stability. The poor water solubility of anticancer drugs, in conjunction with other factors, leads to suboptimal pharmacokinetic performance. Thus, these drugs have limited efficacy and safety when administered orally. The amorphous solid dispersion (ASD) is a promising formulation technology that primarily enhances the aqueous solubility of poorly water-soluble drugs. In this review, we discuss the challenges associated with the oral administration of anticancer drugs and the use of ASD technology in alleviating these challenges. We emphasize the ability of ASDs to improve not only the pharmacokinetics of poorly water-soluble anticancer drugs, but also their efficacy and safety. The goal of this paper is to rationalize the application of ASD technology in the formulation of anticancer drugs, thereby creating superior oncology products that lead to improved therapeutic outcomes.

Polymeric precipitation inhibitor as an effective trigger to convert supersaturated into supersaturable state in vivo

The supersaturated state of the drug in vivo is thermodynamically unstable resulting in a delayed response and reduced efficacy. The use of polymeric precipitation inhibitor (PPI) has been demonstrated as an effective trigger for the conversion of supersaturated state to supersaturable state for improving solubilization, thermodynamic maintenance of drug concentration and oral absorption of poorly water-soluble compounds. PPI retards drug precipitation and provides a kinetically stabilized supersaturation state for an extended period in gastric and intestinal fluids. However, the selection of appropriate PPI and understanding its mechanism is a challenge for formulating a stable pharmaceutical formulation. The present review is aimed at understanding the intricacies of selecting PPIs and their applications in pharmaceutical formulations.

Evaluation of Dissolution Enhancement of Aprepitant Drug in Ternary Pharmaceutical Solid Dispersions with Soluplus® and Poloxamer 188 Prepared by Melt Mixing

In the present study Aprepitant (APT) ternary solid dispersions (SDs) were developed and evaluated for the first time. Specifically, ternary SDs of APT with Poloxamer 188 and Soluplus® (SOL) were prepared via melt mixing and compared to binary APT/Poloxamer 188 and APT/SOL SDs. Initially, combined thermo-gravimetric and hot-stage polarized light microscopy studies indicated that all tested compounds were thermally stable up to 280 °C, while Poloxamer 188 acted as a plasticizer to SOL by significantly reducing the temperature required to fully solubilize the API during SD preparation. Differential scanning calorimetry combined with wide angle X-ray diffraction studies showed that crystalline API was dispersed in both binary and ternary SDs, while Fourier transformation-infrared spectroscopy studies revealed no molecular interactions among the components. Scanning electron microscopy combined with EDAX element analysis showed that the API was dispersed in nano-scale within the polymer matrices, while increasing APT content led to increasing API nano-crystals within the SDs. Finally, dissolution studies showed that the prepared formulations enhanced dissolution of Aprepitant and its mechanism analysis was further studied. A mathematical model was also investigated to evaluate the drug release mechanism.

Aprepitant Drug in Ternary Pharmaceutical Solid Dispersions with Soluplus® and Poloxamer 188 Prepared by Melt Mixing

In the present study Aprepitant (APT) ternary solid dispersions (SDs) were developed and evaluated for the first time. Specifically, ternary SDs of APT with Poloxamer 188 and Soluplus® (SOL) were prepared via melt mixing and compared to binary APT/Poloxamer 188 and APT/SOL SDs. Initially, combined thermo-gravimetric and hot-stage polarized light microscopy studies indicated that all tested compounds were thermally stable up to 280 °C, while Poloxamer 188 acted as a plasticizer to SOL by significantly reducing the temperature required to fully solubilize the API during SD preparation. Differential scanning calorimetry combined with wide angle X-ray diffraction studies showed that crystalline API was dispersed in both binary and ternary SDs, while Fourier transformation-infrared spectroscopy studies revealed no molecular interactions among the components. Scanning electron microscopy combined with EDAX element analysis showed that the API was dispersed in nano-scale within the polymer matrices, while increasing APT content led to increasing API nano-crystals within the SDs. Finally, dissolution studies showed that the prepared formulations enhanced dissolution of Aprepitant and its mechanism analysis was further studied. A mathematical model was also investigated to evaluate the drug release mechanism

Overview of the Manufacturing Methods of Solid Dispersion Technology for Improving the Solubility of Poorly Water-Soluble Drugs and Application to Anticancer Drugs

Approximately 40% of new chemical entities (NCEs), including anticancer drugs, have been reported as poorly water-soluble compounds. Anticancer drugs are classified into biologic drugs (monoclonal antibodies) and small molecule drugs (nonbiologic anticancer drugs) based on effectiveness and safety profile. Biologic drugs are administered by intravenous (IV) injection due to their large molecular weight, while small molecule drugs are preferentially administered by gastrointestinal route. Even though IV injection is the fastest route of administration and ensures complete bioavailability, this route of administration causes patient inconvenience to visit a hospital for anticancer treatments. In addition, IV administration can cause several side effects such as severe hypersensitivity, myelosuppression, neutropenia, and neurotoxicity. Oral administration is the preferred route for drug delivery due to several advantages such as low cost, pain avoidance, and safety. The main problem of NCEs is a limited aqueous solubility, resulting in poor absorption and low bioavailability. Therefore, improving oral bioavailability of poorly water-soluble drugs is a great challenge in the development of pharmaceutical dosage forms. Several methods such as solid dispersion, complexation, lipid-based systems, micronization, nanonization, and co-crystals were developed to improve the solubility of hydrophobic drugs. Recently, solid dispersion is one of the most widely used and successful techniques in formulation development. This review mainly discusses classification, methods for preparation of solid dispersions, and use of solid dispersion for improving solubility of poorly soluble anticancer drugs.

Surfactant-free solid dispersion of BCS class IV drug in an amorphous chitosan oligosaccharide matrix for concomitant dissolution in vitro - permeability increase

Saccharides have been applied as a water-soluble matrix for dispersing hydrophobic drugs homogeneously without the need to use surfactants in amorphous solid dispersions (ASD). Up to now, concomitant permeability improvement of BCS Class IV drug by such matrices have not been much appreciated. Herein, an amorphous chitosan oligosaccharide (COS) was used as matrix to prepare surfactant-free ASD of BCS class IV drug by the ball milling method, with curcumin (CUR) as a model drug. The DSC, XRPD, FTIR and physical stability experiments indicated that CUR was in an amorphous state with high physical stability and exhibited potential interactions with COS in the ASD. Non-sink dissolution in vitro studies showed the maximum dissolution concentration of all CUR-COS ASD (CUR and COS at weight ratios of 1:1, 1:2 and 1:4) reached ranging from 97.85 to 101.21 μg/mL, far above that of pure CUR. The supersaturated concentration remained for at least 24 h under non-sink condition. Caco-2 cell model revealed that, compared to the pure CUR group, the apparent permeability coefficients were increased by 1.72-4.44-fold in all three CUR-COS ASD, which was mainly attributed to opening the tight junctions of Caco-2 cells by COS. The pharmacokinetic study showed that all CUR-COS ASD groups exhibited significant enhancements in AUC_0-∞, with 1.55-3.01-fold that of pure CUR (p < 0.01). T_max of CUR was shortened after oral administration of all three ASD. The current study demonstrates the amorphous COS could be used as a promising matrix in ASD for enhancing the oral bioavailability of BCS class IV drug by improving dissolution behavior and membrane permeability.