Enhancement of the Bioavailability and Anti-Inflammatory Activity of Glycyrrhetinic Acid via Novel Soluplus®—A Glycyrrhetinic Acid Solid Dispersion

Soluplus®-Based Pharmaceutical Formulations: Recent Advances in Drug Delivery and Biomedical Applications

Poor water solubility remains a significant challenge in the pharmaceutical industry that limits the therapeutic efficacy and bioavailability of many active pharmaceuticals. Soluplus® (SLP), an amphiphilic graft copolymer made of polyethylene glycol, polyvinyl caprolactam, and polyvinyl acetate, has been gaining interest in recent years as it addresses these limitations by acting as a versatile carrier. Its ability to form stable amorphous dispersions and enhance drug solubility, as well as its physicochemical properties, support its role as a key excipient in advanced drug delivery systems. Recent investigations have demonstrated the adaptability of SLP in addressing drug delivery requirements, offering controlled release, improved targeting, and superior therapeutic outcomes. This review examines some key formulation methods that make use of SLP, including hot-melt extrusion, spray drying, electrospinning, drug-polymer layering, and capsule and tablet formulations, highlighting the capacity of SLP to overcome formulation challenges. Biomedical applications of SLP have also been explored, with a focus on its role in improving the delivery of antitumoral, anti-inflammatory, antimicrobial, and antiparasitic 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.

A review of typical biological activities of glycyrrhetinic acid and its derivatives

Glycyrrhetinic acid, a triterpenoid compound primarily sourced from licorice root, exhibits noteworthy biological attributes, including anti-inflammatory, anti-tumor, antibacterial, antiviral, and antioxidant effects. Despite these commendable effects, its further advancement and application, especially in clinical use, have been hindered by its limited druggability, including challenges such as low solubility and bioavailability. To enhance its biological activity and pharmaceutical efficacy, numerous research studies focus on the structural modification, associated biological activity data, and underlying mechanisms of glycyrrhetinic acid and its derivatives. This review endeavors to systematically compile and organize glycyrrhetinic acid derivatives that have demonstrated outstanding biological activities over the preceding decade, delineating their molecular structures, biological effects, underlying mechanisms, and future prospects for assisting researchers in finding and designing novel glycyrrhetinic acid derivatives, foster the exploration of structure-activity relationships, and aid in the screening of potential candidate compounds.

Navigating the Solution to Drug Formulation Problems at Research and Development Stages by Amorphous Solid Dispersion Technology

Amorphous Solid Dispersions (ASDs) have indeed revolutionized the pharmaceutical industry, particularly in drug solubility enhancement. The amorphous state of a drug, which is a highenergy metastable state, can lead to an increase in the apparent solubility of the drug. This is due to the absence of a long-range molecular order, which results in higher molecular mobility and free volume, and consequently, higher solubility. The success of ASD preparation depends on the selection of appropriate excipients, particularly polymers that play a crucial role in drug solubility and physical stability. However, ASDs face challenges due to their thermodynamic instability or tendency to recrystallize. Measuring the crystallinity of the active pharmaceutical ingredient (API) and drug solubility is a complex process that requires a thorough understanding of drug-polymer miscibility and molecular interactions. Therefore, it is important to monitor drug solids closely during preparation, storage, and application. Techniques such as solid-state nuclear magnetic resonance (ssNMR), attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR), Raman spectroscopy, and dielectric spectroscopy have been successful in understanding the mechanism of drug crystallization. In addition, the continuous downstream processing of drug-loaded ASDs has introduced new automated methods for consistent ASD production. Advanced techniques such as hot melt extrusion, KinetiSol, electro spraying, and electrospinning have gained popularity. This review provides a comprehensive overview of Amorphous Solid Dispersions (ASDs) for oral drug delivery. It highlights the critical challenges faced during formulation, the impact of manufacturing variables, theoretical aspects of drug-polymer interaction, and factors related to drug-polymer miscibility. ASDs have been recognized as a promising strategy to improve the oral bioavailability of poorly water-soluble drugs. However, the successful development of an ASD-based drug product is not straightforward due to the complexity of the ASD systems. The formulation and process parameters can significantly influence the performance of the final product. Understanding the interactions between the drug and polymer in ASDs is crucial for predicting their stability and performance.

Influence of Intermolecular Interactions on Crystallite Size in Crystalline Solid Dispersions

Crystalline solid dispersions (CSDs) represent a thermodynamically stable system capable of effectively reducing the crystallite size of drugs, thereby enhancing their solubility and bioavailability. This study uses flavonoid drugs with the same core structures but varying numbers of hydroxyl groups as model drugs and poloxamer 188 as a carrier to explore the intrinsic relationships between drug-polymer interactions, crystallite size, and in vitro dissolution behavior in CSDs. Initially, we investigate the interactions between flavonoid drugs and P188 by calculating Hansen solubility parameters, determination of Flory-Huggins interaction parameters, and other methods. Subsequently, we explore the crystallization kinetics of flavonoid drugs and P188 in CSD systems using polarized optical microscopy and powder X-ray diffraction. We monitor the domain size and crystallite size of flavonoids in CSDs through powder X-ray diffraction and a laser-particle-size analyzer. Finally, we validate the relationship between crystallite size and in vitro dissolution behavior through powder dissolution. The results demonstrate that, as the number of hydroxyl groups increases, the interactions between drugs and polymers become stronger, making drug crystallization in the CSD system less likely. Consequently, reductions in crystalline domain size and crystallite size become more pronounced, leading to a more significant enhancement in drug dissolution.

Nanofibers of Glycyrrhizin/Hydroxypropyl-β-Cyclodextrin Inclusion Complex: Enhanced Solubility Profile and Anti-inflammatory Effect of Glycyrrhizin

Despite having a wide range of therapeutic advantages, glycyrrhizin (GL) has few commercial applications due to its poor aqueous solubility. In this study, we combined the benefits of hydroxypropyl β-cyclodextrin (HP-βCD) supramolecular inclusion complexes and electrospun nanofibers to improve the solubility and therapeutic potential of GL. A molecular inclusion complex containing GL and HP-βCD was prepared by lyophilization at a 1:2 molar ratio. GL and hydroxypropyl β-cyclodextrin inclusion complexes were also incorporated into hyaluronic acid (HA) nanofibers. Prepared NF was analyzed for physical, chemical, thermal, and pharmaceutical properties. Additionally, a rat model of carrageenan-induced hind paw edema and macrophage cell lines was used to evaluate the anti-inflammatory activity of GL-HP-βCD NF. The DSC and XRD analyses clearly showed the amorphous state of GL in nanofibers. In comparison to pure GL, GL-HP-βCD NF displayed improved release (46.6 ± 2.16% in 5 min) and dissolution profiles (water dissolvability ≤ 6 s). Phase solubility results showed a four-fold increase in GL solubility in GL-HP-βCD NF. In vitro experiments on cell lines showed that inflammatory markers like IL-1β, TNF-α, and IL-6 were significantly lower in GL-HP-βCD NF compared to pure GL (p < 0.01 and p < 0.05). According to in vivo results, the prepared nanofiber exhibits a better anti-inflammatory effect than pure GL (63.4% inhibition vs 53.7% inhibition). The findings presented here suggested that GL-HP-βCD NF could serve as a useful strategy for improving the therapeutic effects of GL.

Anti-Inflammatory Properties of Plants from Serbian Traditional Medicine

Inflammation is a natural protective response of the human body to a variety of hostile agents and noxious stimuli. Standard anti-inflammatory therapy includes drugs whose usage is associated with a number of side effects. Since ancient times, natural compounds have been used for the treatment of inflammation. Traditionally, the use of medicinal plants is considered safe, inexpensive, and widely acceptable. In Serbia, traditional medicine, based on the strong belief in the power of medicinal herbs, is the widespread form of treatment. This is supported by the fact that Serbia is classified as one of 158 world centers of biodiversity, which confirms that this country is a treasure of medicinal herbs. Some of the most used herbs for the treatment of inflammations of various causes in Serbian tradition are yarrow, common agrimony, couch grass, onion, garlic, marshmallow, common birch, calendula, liquorice, walnut, St. John’s wort, chamomile, peppermint, white willow, sage, and many others. The biological activity and anti-inflammatory effect of selected plants are attributed to different groups of secondary biomolecules such as flavonoids, phenolic acids, sterols, terpenoids, sesquiterpenes, and tannins. This paper provides an overview of plants with traditional anti-inflammatory use in Serbia with reference to available studies that examined this effect. Plants used in traditional medicine could be a powerful source for the development of new remedies. Therefore intensive research on the bioactive potential of medicinal plants in each region should be the focus of scientists around the world.

Polymers Enhancing Bioavailability in Drug Delivery

A drug's bioavailability, i.e., the extent to and rate at which it enters the systemic circulation, thus accessing the site of action, is largely determined by the properties of the drug [...].