A Hydroxypropyl Methylcellulose-Based Solid Dispersion of Curcumin with Enhanced Bioavailability and its Hepatoprotective Activity

The prescription design and key properties of nasal gel for CNS drug delivery: A review

Central nervous system (CNS) diseases are among the major health problems. However, blood-brain barrier (BBB) makes traditional oral and intravenous delivery of CNS drugs inefficient. The unique direct connection between the nose and the brain makes nasal administration a great potential advantage in CNS drugs delivery. However, nasal mucociliary clearance (NMCC) limits the development of drug delivery systems. Appropriate nasal gel viscosity alleviates NMCC to a certain extent, gels based on gellan gum, chitosan, carbomer, cellulose and poloxamer have been widely reported. However, nasal gel formulation design and key properties for alleviating NMCC have not been clearly discussed. This article summarizes gel formulations of different polymers in existing nasal gel systems, and attempts to provide a basis for researchers to conduct in-depth research on the key characteristics of gel matrix against NMCC.

Solubilisation and Enhanced Oral Absorption of Curcumin Using a Natural Non-Nutritive Sweetener Mogroside V

Background

Curcumin (CUR) is a functional ingredient from the spice turmeric. It has attracted considerable attention recently, owing to its diverse biological activities. However, curcumin has low water solubility, which limited its applications. Some sugar molecules were found to be able to solubilise poorly water-soluble compounds by forming micelles in aqueous solutions.

Purpose

To improve the water solubility and oral absorption of CUR, using a non-nutritive natural sweetener, namely, Mogroside V (Mog-V).

Methods

A solid dispersion of CUR in Mog-V was prepared using a solvent evaporation method. The solid dispersion was characterised by using X-ray diffraction and differential scanning calorimetry. The solid dispersion can dissolve in water to form micelles with a diameter of ~160 nm, which were characterised by using dynamic light scattering. To find out the mechanism of solubilisation, the aggregation behaviour of Mog-V molecules in aqueous solution was investigated using nuclear magnetic resonance spectroscopy. Finally, oral absorption of CUR in the solid dispersion was evaluated using a rodent model.

Results

A solid dispersion was formed in a ratio of 1 CUR to 10 Mog-V by weight. Upon dissolution into water, CUR laden micelles formed via self-assembly of Mog-V molecules, which increased the solubility of CUR by nearly 6000 times compared with pure CUR crystals. In rats, the solid dispersion increased the oral absorption of CUR by 29 folds, compared with CUR crystals. In terms of solubilisation mechanism, it was found that Mog-V self-assembled into micelles with a core-shell structure and CUR molecules were incorporated into the hydrophobic core of the Mog-V micelles.

Conclusion

Mog-V can form a solid dispersion with CUR. Upon dissolution in water, the Mog-V in the solid dispersion can self-assemble into micelles, which solubilise CUR and increase its oral absorption.

Interaction of polymers with bile salts - Impact on solubilisation and absorption of poorly water-soluble drugs

Formulating poorly soluble drugs with polymers in the form of solid dispersions has been widely used for improving drug dissolution. Endogenous surface-active species present in the gut, such as bile salts, lecithin and other phospholipids, have been shown to play a key role in facilitating lipids and poorly soluble drugs solubilisation in the gut. In this study, we examined the possible occurrence of interactions between a model bile salt, sodium taurocholate (NaTC), and model spray dried solid dispersions comprising piroxicam and Hydroxypropyl Methylcellulose (HPMC), a commonly used hydrophilic polymer for solid dispersion preparation. Solubility measurements revealed the good solubilisation effect of NaTC on the crystalline drug, which was enhanced by the addition of HPMC, and further boosted by the drug formulation into solid dispersion. The colloidal behaviour of the solid dispersions upon dissolution in biorelevant media, with and without NaTC, revealed the formation of NaTC-HPMC complexes and other mixed colloidal species. Cellular level drug absorption studies obtained using Caco-2 monolayers confirmed that the combination of drug being delivered by solid dispersion and the presence of bile salt and lecithin significantly contributed to the improved drug absorption. Together with the role of NaTC-HPMC complexes in assisting the drug solubilisation, our results also highlight the complex interplay between bile salts, excipients and drug absorption.

Current Trends on Solid Dispersions: Past, Present, and Future

Solid dispersions have achieved significant interest as an effective means of enhancing the dissolution rate and thus the bioavailability of a range of weakly water-soluble drugs. Solid dispersions of weakly water-soluble drugs with water-soluble carriers have lowered the frequency of these problems and improved dissolution. Solid dispersion is a solubilization technology emphasizing mainly on, drug-polymer two-component systems in which drug dispersion and its stabilization is the key to formulation development. Therefore, this technology is recognized as an exceptionally useful means of improving the dissolution properties of poorly water-soluble drugs and in the latest years, a big deal of understanding has been accumulated about solid dispersion, however, their commercial application is limited. In this review article, emphasis is placed on solubility, BCS classification, and carriers. Moreover, this article presents the diverse preparation techniques for solid dispersion and gathers some of the recent technological transfers. The different types of solid dispersions based on the carrier used and molecular arrangement were underlined. Additionally, it summarizes the mechanisms, the methods of preparing solid dispersions, and the marketed drugs that are available using solid dispersion approaches.

Solid dispersion technology as a formulation strategy for the fabrication of modified release dosage forms: A comprehensive review

Solubility limited bioavailability is one of the crucial parameters that affect the formulation development of the new chemical entities. Thus the major constraint in the pharmaceutical product development is the suitable solubility enhancement technique for Active Pharmaceutical Ingredient. Solid dispersion (SD) is an established and preferred method for improving the solubility which ultimately may be helpful to enhance bioavailability. For long period of time Amorphous solid dispersion (ASD) have been preferred for improving solubility, but since last two decades, ASD approach have been combined with different modified release approaches to improvise the stability and site specificity of SD to grasp a hold over the specific advantages associated with such dosage forms. It is an established fact now that the SD technique not only improves solubility limited bioavailability, but it may be combined with other approaches to modify the drug release profile from the formulation as per the requirement based on the apt selection of SD carriers and suitable technology. This review covers the comprehensive overview of all such formulations where SD technology is used to serve dual purpose rather than only the sole purpose of solubility enhancement. The SD approach has been successfully implemented for some of the poorly soluble herbal drugs and still there is a vast scope of advancement in that area. The current review will provide a broad outcome in the area of SD technology for modified release formulations along with the description of current status and future prospective of SD. The SD formed by dispersing drug within the conventional carrier to form ASD increases solubility, dissolution rate and bioavailability; whereas fourth generation hydrophobic carriers provide added advantage of controlled release (CR) or sustained release (SR) profile along with enhanced stability of SD. On the other frontier, pH dependant carriers enable the SD to achieve site specificity or delayed release (DR) profile.

Observation of curcumin-loaded hydroxypropyl methylcellulose (HPMC) oleogels under in vitro lipid digestion and in situ intestinal absorption in rats

Curcumin-loaded nanostructured lipid carriers (Cur-NLCs)-based hydroxypropyl methylcellulose (HPMC) oleogels (Cur-NLCs-HPMC-OGs) were fabricated using a cryogel template. The effect of the HPMC viscosity grade on the oleogel characteristics and in situ intestinal absorption were examined. Highly stable Cur-NLCs were prepared with a mean particle size of 314 nm and polydispersity index of 0.275. Cur-NLCs affected the creamy texture of self-standing Cur-NLCs-HPMC-OGs. The Cur-NLCs were tightly packed as oil droplets in the network of HPMC. However, a high viscosity of HPMC-4000 led to a greater ability to entrap and prevent droplet coalescence compared to a low viscosity of HPMC-400. NLCs promoted the release of free fatty acids during in vitro lipid digestion, whereas HPMC-4000 maintained the strength and durability of oleogels against mechanical and enzymatic breakdown. The in situ loop results revealed higher curcumin absorption by Cur-NLCs-HPMC-OGs than by Cur-HPMC-OGs. HMPC-4000 showed slightly higher curcumin absorption compared to HPMC-400.

Molecular networking-guided strategy for the pharmacokinetic study of herbal medicines: Cudrania tricuspidata leaf extracts

In this study, the pharmacokinetic profiles of the bioactive components in the leaf extract of the medicinal herb, Cudrania tricuspidate, were investigated using an MS/MS-based molecular networking system. To identify the major active components of the C. tricuspidate leaf extract (CLE), HPLC-DAD analysis was conducted with a standard mixture of six flavonoids (rutin, isoquercitrin, nicotiflorin, kaempferol 3-O-glucoside, quercetin, and kaempferol). The unknown peaks were determined via molecular networking analysis using the mass dataset obtained by liquid chromatography quadrupole time-of-flight mass spectrometry (LC-QTOF/MS). For the subsequent pharmacokinetic study, CLE (1 g/kg) was orally administered to rats, and plasma samples were collected. The product ion mass data of plasma samples using LC-QTOF/MS were obtained and subjected to molecular networking analysis. The resulting molecular networking map indicated that the glucuronide metabolites of quercetin and kaempferol were the major circulating species. Accordingly, quercetin and kaempferol were determined following β-glucuronidase treatment, and their pharmacokinetic parameters were calculated. These findings indicate that the proposed molecular network-based approaches are potential and efficient methods for the pharmacokinetic study of herbal medicines.

Drug Delivery Strategies for Curcumin and Other Natural Nrf2 Modulators of Oxidative Stress-Related Diseases

Oxidative stress is associated with a wide range of diseases characterised by oxidant-mediated disturbances of various signalling pathways and cellular damage. The only effective strategy for the prevention of cellular damage is to limit the production of oxidants and support their efficient removal. The implication of the nuclear factor erythroid 2-related factor 2 (Nrf2) pathway in the cellular redox status has spurred new interest in the use of its natural modulators (e.g., curcumin, resveratrol). Unfortunately, most natural Nrf2 modulators are poorly soluble and show extensive pre-systemic metabolism, low oral bioavailability, and rapid elimination, which necessitates formulation strategies to circumvent these limitations. This paper provides a brief introduction on the cellular and molecular mechanisms involved in Nrf2 modulation and an overview of commonly studied formulations for the improvement of oral bioavailability and in vivo pharmacokinetics of Nrf2 modulators. Some formulations that have also been studied in vivo are discussed, including solid dispersions, self-microemulsifying drug delivery systems, and nanotechnology approaches, such as polymeric and solid lipid nanoparticles, nanocrystals, and micelles. Lastly, brief considerations of nano drug delivery systems for the delivery of Nrf2 modulators to the brain, are provided. The literature reviewed shows that the formulations discussed can provide various improvements to the bioavailability and pharmacokinetics of natural Nrf2 modulators. This has been demonstrated in animal models and clinical studies, thereby increasing the potential for the translation of natural Nrf2 modulators into clinical practice.

Preparation of Curcumin-Eudragit® E PO Solid Dispersions with Gradient Temperature through Hot-Melt Extrusion

Hot-melt extrusion (HME) has great advantages for the preparation of solid dispersion (SD), for instance, it does not require any organic solvents. Nevertheless, its application to high-melting-point and thermosensitive drugs has been rarely reported. In this study, thermally unstable curcumin (Cur) was used as a drug model. The HME process was systematically studied by adjusting the gradient temperature mode and residence time, with the content, crystallinity and dissolution of Cur as the investigated factors. The effects of barrel temperature, screw speed and cooling rate on HME were also examined. Solubility parameters and the Flory-Huggins method were used to evaluate the miscibility between Cur and carriers. Differential scanning calorimetry, X-ray diffraction, Fourier transform infrared spectroscopy, equilibrium solubility and in vitro and in vivo experiments were used to characterize and evaluate the results. An amorphous Cur SD was successfully obtained, increasing the solubility and release of Cur. In the optimal process, the mass ratio of Cur to Eudragit® E PO (EPO) was 1:4 and the barrel temperature was set at a gradient heating mode (130 °C-135 °C-140 °C-145 °C-150 °C-155 °C-160 °C) at 100 rpm. Related pharmacokinetic test results also showed the improved bioavailability of the drug in rats. In a pharmacodynamic analysis of Sprague-Dawley rats, the Cmax and the bioavailability of the Cur-EPO SD were 2.6 and 1.5 times higher than those of Cur, respectively. The preparation of the amorphous SD not only provided more solubility but also improved the bioavailability of Cur, which provides an effective way to improve the bioavailability of BCS II drugs.

Curcumin-incorporated crosslinked sodium alginate-g-poly (N-isopropyl acrylamide) thermo-responsive hydrogel as an in-situ forming injectable dressing for wound healing: In vitro characterization and in vivo evaluation

Sodium alginate products have been extensively used for wound-dressing. In present study, a series of thermo-sensitive cross-linked poly(N-isopropylacrylamide) grafted sodium alginate (Alg-g-pNIPAM) copolymers were synthesized for delivery of curcumin to wound. FTIR, ¹H NMR, elemental analysis and DSC showed successful polymerization and precise structure of copolymers. Thermogelation at 27-42 °C depending on the copolymer concentration, chain-length of pNIPAM and pH was observed. The optimum copolymer with proper rheological and syringeability properties showed excellent thermogelling at a wide range of pH and concentration, and could prolong the release of curcumin up to 72 h. In-vivo wound contraction and histopathological evaluations revealed that in addition to the higher efficacy in wound contraction, the curcumin formulation (Cur-F) significantly reduced the inflammation, enhanced the collagenesis and resulted in increased number of fibroblasts. Well-known anti-oxidant and anti-inflammatory properties of curcumin and in situ-forming nature of Alg-g-pNIPAM can make the system an excellent candidate for further investigations.

Controlled Release of Curcumin from HPMC (Hydroxypropyl Methyl Cellulose) Co-Spray-Dried Materials

In order to achieve the controlled release of curcumin, HPMC (hydroxypropyl methyl cellulose) was spray dried with curcumin and lactose. The spray-dried materials were pressed into tablets with a diameter of 8 mm, and their release characteristics in vitro were measured. In vitro experiments showed that the release of curcumin from the HPMC mixture was significantly slower due to the sustained-release property of HPMC as a typical excipient. The release profile of curcumin from the HPMC mixture was relatively stable for a controlled release. SEM images show that the HPMC co-spray-dried powders have crumpled surfaces due to the large molecular weight of HPMC. DSC, XRD, FTIR, N2 adsorption, and TGA have been measured for the spray-dried curcumin materials. This work indicates that HPMC can be used as a controlled-release excipient for curcumin preparations.

Formulation optimization of solid self-microemulsifying pellets for enhanced oral bioavailability of curcumin

Solidification of self-microemulsifying drug delivery systems (SMEDDS) is one of the major trends to promote the transformation of self-microemulsion technology into industrialization. Here, a preliminary curcumin SMEDDS formulation was constructed to improve the druggability of curcumin, through the determination of equilibrium solubility determination, self-emulsifying grading assessment, and pseudo-ternary phase diagrams drafting. Furthermore, the optimal curcumin SMEDDS formulation consisted of 10% Ethyl oleate, 57.82% Cremophor RH 40, and 32.18% Transcutol P was obtained by the simplex lattice design. Besides, curcumin solid self-microemulsifying drug delivery system (S-SMEDDS) was developed by the extrusion and spheronization process to achieve the solidification of SMEDDS. The formulation of curcumin S-SMEDDS pellets was screened by the single factor experiment and the process parameters were investigated using the orthogonal optimization method. Subsequently, curcumin S-SMEDDS pellets were evaluated by apparent morphology characterization, redispersibility study, drug release behavior, and pharmacokinetic evaluation. Results from the pharmacokinetic study in rabbits showed that the AUC_0-τ of the curcumin S-SMEDDS pellets and curcumin suspension were 5.91 ± 0.28 µg/mL·h and 2.05 ± 0.04 µg/mL·h, while the relative bioavailability was 289.30%. These studies demonstrated that S-SMEDDS pellets can be a promising strategy for curcumin industrialized outputs.

Novel Therapeutic Delivery of Nanocurcumin in Central Nervous System Related Disorders

Nutraceuticals represent complementary or alternative beneficial products to the expensive and high-tech therapeutic tools in modern medicine. Nowadays, their medical or health benefits in preventing or treating different types of diseases is widely accepted, due to fewer side effects than synthetic drugs, improved bioavailability and long half-life. Among herbal and natural compounds, curcumin is a very attractive herbal supplement considering its multipurpose properties. The potential effects of curcumin on glia cells and its therapeutic and protective properties in central nervous system (CNS)-related disorders is relevant. However, curcumin is unstable and easily degraded or metabolized into other forms posing limits to its clinical development. This is particularly important in brain pathologies determined blood brain barrier (BBB) obstacle. To enhance the stability and bioavailability of curcumin, many studies focused on the design and development of curcumin nanodelivery systems (nanoparticles, micelles, dendrimers, and diverse nanocarriers). These nanoconstructs can increase curcumin stability, solubility, in vivo uptake, bioactivity and safety. Recently, several studies have reported on a curcumin exosome-based delivery system, showing great therapeutical potential. The present work aims to review the current available data in improving bioactivity of curcumin in treatment or prevention of neurological disorders.

Amorphous systems for delivery of nutraceuticals: challenges opportunities

Amorphous solid products have recently gained a lot of attention as key solutions to improve the solubility and bioavailability of poorly soluble nutraceuticals. A pure amorphous drug is a high-energy form; physically/chemically unstable and so easily gets recrystallized into the less soluble crystalline form limiting solubility and bioavailability issues. Amorphous solid dispersion and co-amorphous are new formulation approach that stabilized unstable amorphous form through different mechanisms such as preventing mobility, high glass transition temperature and molecular interaction. Nutraceuticals have been received the utmost importance due to their health benefits. However, most of these compounds have been associated with poor oral bioavailability due to poor solubility, high lipophilicity, high melting point, poor permeability, degradability and rapid metabolism in the gastrointestinal tract (GIT) which limits its health benefits. This review provides us a systematic application of amorphous systems to the delivery of poorly soluble nutraceuticals, with the aim of overcoming their pharmacokinetic limitations and improved pharmacological potential. In particular, it describes the challenges associated with delivery of oral nutraceuticals, various methods involved in the preparation and characterization of amorphous systems and permeability enhancement of nutraceuticals are in detail.

Therapeutic Applications of Solid Dispersions for Drugs and New Molecules: In Vitro and In Vivo Activities

This review aims to provide an overview of studies that address the use, in therapeutic applications, of solid dispersions (SDs) with biological activities in vitro and/or in vivo mainly made up of polymeric matrices, as well as to evaluate the bioactive activity of their constituents. This bibliographic survey shows that the development of solid dispersions provides benefits in the physicochemical properties of bioactive compounds, which lead to an increase in their biological potential. However, despite the reports found on solid dispersions, there is still a need for biological assay-based studies, mainly in vivo, to assist in the investigation and to devise new applications. Therefore, studies based on such an approach are of great importance to enhance and extend the use of solid dispersions in the most diverse therapeutic applications.

Evaluation of the Solid Dispersion System Engineered from Mesoporous Silica and Polymers for the Poorly Water Soluble Drug Indomethacin: In Vitro and In Vivo

This work explored absorption efficacy via an in vivo imaging system and parallel artificial membrane penetration in indomethacin (IMC) solid dispersion (SD) systems. Two different polymer excipients—hydroxypropyl methylcellulose (HPMC) and Kollicoat IR as precipitation inhibitors (PIs)—combined with mesoporous silica nanoparticles (MSNs) as carriers were investigated. The IMC–SDs were prepared using the solvent evaporation method and characterized by solubility analysis, infrared (IR) spectroscopy, powder X-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM), and differential scanning calorimetry (DSC). It was confirmed that IMC successfully changed into an amorphous state after loading into the designed carriers. The in vitro release and stability experiments were conducted to examine the in vitro dissolution rates of IMC–SDs combined with HPMC and Kollicoat IR as PIs which both improved approximately three-fold to that of the pure drug. Finally, in vivo studies and in vitro parallel artificial membrane penetration (PAMPA) experiments ensured the greater ability of enhancing the dissolution rates of pure IMC in the gastrointestinal tract by oral delivery. In brief, this study highlights the prominent role of HPMC and Kollicoat IR as PIs in MSN SD systems in improving the bioavailability and gastrointestinal oral absorption efficiency of indomethacin.

Polysaccharide-Based Formulations for Healing of Skin-Related Wound Infections: Lessons from Animal Models and Clinical Trials

Skin injuries constitute a gateway for pathogenic bacteria that can be either part of tissue microbiota or acquired from the environmental. These microorganisms (such as Acinetobacter baumannii, Enterococcus faecalis,Pseudomonas aeruginosa, and Staphylococcus aureus) produce virulence factors that impair tissue integrity and sustain the inflammatory phase leading for establishment of chronic wounds. The high levels of antimicrobial resistance have limited the therapeutic arsenal for combatting skin infections. Thus, the treatment of non-healing chronic wounds is a huge challenge for health services worldwide, imposing great socio-economic damage to the affected individuals. This scenario has encouraged the use of natural polymers, such as polysaccharide, in order to develop new formulations (membranes, nanoparticles, hydrogels, scaffolds) to be applied in the treatment of skin infections. In this non-exhaustive review, we discuss the applications of polysaccharide-based formulations in the healing of infected wounds in animal models and clinical trials. The formulations discussed in this review were prepared using alginate, cellulose, chitosan, and hyaluronic acid. In addition to have healing actions per se, these polysaccharide formulations can act as transdermal drug delivery systems, controlling the release of active ingredients (such as antimicrobial and healing agents). The papers show that these polysaccharides-based formulations are efficient in controlling infection and improve the healing, even in chronic infected wounds. These data should positively impact the design of new dressings to treat skin infections.