Surfactant-Free Solid Dispersions of Hydrophobic Drugs in an Amorphous Sugar Matrix Dried from an Organic Solvent

Oral nano-formulations for endocrine therapy of endometrioid adenocarcinomas

Endometrial cancer is one of the three major malignant tumors of the reproductive system that threaten women's lives and health. The incidence of this disease is on the rise globally. Most cases of endometrial cancer comprise endometrioid adenocarcinomas, whose treatment is challenged by factors such as their high recurrence rate and the need to preserve fertility among young patients. Thus, oral endocrine therapy has become the main treatment modality. The main drugs used in oral endocrine therapy are progestins, selective estrogen receptor antagonists, and aromatase inhibitors. However, their clinical use is hindered by their low solubility and low oral utilization. The rapid development of nanotechnology allows the combination of these drugs with oral nano-formulations to create a good carrier. Such nanocarriers, including nanospheres, nanocapsules, and micelles can protect the drug against clearance and increase the site specificity of drug delivery. This paper reviews the pathogenesis of endometrioid endometrial cancer (EEC) and oral nano-formulations for endocrine therapy.

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

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

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

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

Co-amorphous systems using epigallocatechin-3-gallate as a co-former: stability, in vitro dissolution, in vivo bioavailability and underlying molecular mechanisms

Co-amorphous strategy has been extensively investigated to improve the dissolution of hydrophobic drugs. Here, epigallocatechin-3-gallate (EGCG) was exploited as a co-former in co-amorphous systems based on its unique structure including phenyl rings, phenolic hydroxyl groups and the galloyl moiety. Two model BCS class II drugs, simvastatin (SIM) and nifedipine (NIF), were selected to be co-amorphized with EGCG. All drug-EGCG systems at three molar ratios became amorphous by the means of spray drying and showed high physically stable either under dry condition and 75% RH at 40 °C or under dry conditions at 25 °C. The optimal feed molar ratios of both EGCG based co-amorphous systems fabricated were determined to be three, under which the significant increases were obtained in the maximum apparent concentrations of 4.90-fold for SIM at 1 h and 106.03-fold for NIF at 0.25 h compared to crystalline drugs by non-sink dissolution studies. The underlying molecular mechanisms of two co-amorphous systems formation were involved in molecular miscibility, hydrogen bonds and π-π stacking interactions unraveled by means of DSC, FTIR and molecular dynamics simulations. More to the point, oral pharmacokinetic studies in rats demonstrated that co-amorphous SIM-EGCG and NIF-EGCG systems at 1:3 have a significant increase in C_max of 1.81- and 5.69-fold, and AUC _{0-24 h} of 1.62- and 4.57-fold compared with those of corresponding crystalline drugs, respectively. In conclusion, EGCG is proved to be a promising co-former in co-amorphous systems.

Formulation and In Vitro Characterization of a Vacuum-Dried Drug–Polymer Thin Film for Intranasal Application

Intranasal drug applications show significant therapeutic potential for diverse pharmaceutical modalities. Because the formulation applied to the nasal cavity is discharged to the pharyngeal side by mucociliary clearance, the formulation should be dissolved effectively in a limited amount of mucus within its retention time in the nasal cavity. In this study, to develop novel formulations with improved dissolution behavior and compatibility with the intranasal environment, a thin-film formulation including drug and polymer was prepared using a vacuum-drying method. The poorly water-soluble drugs ketoprofen, flurbiprofen, ibuprofen, and loxoprofen were dissolved in a solvent comprising water and methanol, and evaporated to obtain a thin film. Physical analyses using differential scanning calorimetry (DSC), powder X-ray diffraction analysis (PXRD), and scanning electron microscopy SEM revealed that the formulations were amorphized in the film. The dissolution behavior of the drugs was investigated using an in vitro evaluation system that mimicked the intranasal physiological environment. The amorphization of drugs formulated with polymers into thin films using the vacuum-drying method improved the dissolution rate in artificial nasal fluid. Therefore, the thin film developed in this study can be safely and effectively used for intranasal drug application.

Noncovalent Association and Partitioning of Some Perfume Components at Infinite Dilution with Myelin Basic Protein Pseudophase in Normal Saline

Myelin basic protein (MBP), one of the major protein constituents of the myelin sheath, possesses unique ligand-binding features. We present a novel equilibrium headspace gas chromatographic technique to examine the thermodynamics of noncovalent interactions between common perfume components: Lilial, Hedione, Hexylcinnamic aldehyde, and Versalide with MBP monomers and its hexameric MBP-pseudophase. A general theoretical model is used to calculate the critical aggregation concentration (cac) of MBP, perfume component binding constants with monomeric MBP, K₁₁, and MBP as pseudophase, K_n1, and free energies for perfume component binding with monomeric MBP, ΔG_b,11, and MBP as pseudophase, ΔG_b,n1. In addition, the pseudophase-water partition coefficients, K_x, the free energies of transfer of perfume from bulk water to the MBP-pseudophase, ΔG_t, and the intra-aggregate activity coefficients, γ_m^∞, at infinite dilution were also determined. The cac value measured by the method of fractional distribution is a unique and precise approach in understanding the aggregation phenomenon. Within the experimental error, the 1:1 binding free energies did not differ by more than 1 kJ/mol among the perfume components but favored the MBP pseudophase binding by 6 kJ/mol. Therefore, that protein aggregation can enhance the binding of small molecules is probably a general conclusion. While the magnitudes of K₁₁, K_n1, ΔG_b, K_x, and ΔG_t show weak trends, the γ_m^∞ values show a strong and distinct trend in interaction, spanning 4 orders of magnitude among the perfume components.

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.

Cocrystal Solubility Advantage Diagrams as a Means to Control Dissolution, Supersaturation, and Precipitation

Cocrystals are often more soluble than needed and pose unnecessary risks for precipitation of less soluble forms of the drug during processing and dissolution. Such conversions lead to erratic cocrystal behavior and nullify the cocrystal solubility advantage over parent drug (SA = Scocrystal/Sdrug). This work demonstrates a quantitative method for additive selection to control cocrystal disproportionation based on cocrystal solubility advantage (SA) diagrams. The tunability of cocrystal SA is dependent on the selective drug-solubilizing power of surfactants (SPdrug = (ST/Saq)drug). This cocrystal property is used to generate SA-SP diagrams that facilitate surfactant selection and provide a framework for evaluating how SA influences drug concentration-time profiles associated with cocrystal dissolution, drug supersaturation, and precipitation (DSP). Experimental results with indomethacin-saccharin cocrystal and surfactants (sodium lauryl sulfate, Brij, and Myrj) demonstrate the log-linear relationship characteristic of SA-SP diagrams and the dependence of σmax and dissolution area under the curve (AUC) on SA with characteristic maxima at a threshold supersaturation where drug nucleation occurs. This approach is expected to streamline cocrystal formulation as it facilitates additive selection by considering the interplay between thermodynamic (SA) and kinetic (DSP) processes.

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.

A general approach for encapsulating organic crystals in a polyaniline shell

The hydrophobicity and instability of organic crystals restrict their further applications. Here, we present a general and scalable method to encapsulate different organic crystals in a conductive polyaniline (PANI) shell. The shell significantly improves the stability and dispersity of the nanocrystals, without compromising their luminescence intensity.