Mucoadhesive Delivery System: A Smart Way to Improve Bioavailability of Nutraceuticals

Hard Gelatin Capsules with Alginate-Hypromellose Microparticles as a Multicompartment Drug Delivery System for Sustained Posaconazole Release

Microparticles as a multicompartment drug delivery system are beneficial for poorly soluble drugs. Mucoadhesive polymers applied in microparticle technology prolong the contact of the drug with the mucosa surface enhancing drug bioavailability and extending drug activity. Sodium alginate (ALG) and hydroxypropyl methylcellulose (hypromellose, HPMC) are polymers of a natural or semi-synthetic origin, respectively. They are characterized by mucoadhesive properties and are applied in microparticle technology. Spray drying is a technology employed in microparticle preparation, consisting of the atomization of liquid in a stream of gas. In this study, the pharmaceutical properties of spray-dried ALG/HPMC microparticles with posaconazole were compared with the properties of physical mixtures of powders with equal qualitative and quantitative compositions. Posaconazole (POS) as a relatively novel antifungal was utilized as a model poorly water-soluble drug, and hard gelatin capsules were applied as a reservoir for designed formulations. A release study in 0.1 M HCl showed significantly prolonged POS release from microparticles compared to a mixture of powders. Such a relationship was not followed in simulated vaginal fluid (SVF). Microparticles were also characterized by stronger mucoadhesive properties, an increased swelling ratio, and prolonged residence time compared to physical mixtures of powders. The obtained results indicated that the pharmaceutical properties of hard gelatin capsules filled with microparticles were significantly different from hard gelatin capsules with mixtures of powders.

Electrospun Fibers Loaded with Probiotics: Fundamentals, Characterization, and Applications

Increasing demand for safe, efficient, and eco-friendly solutions for pharmaceutical and food industries has led researchers to explore new approaches to bacterial storage. Several advantages make electrospinning (ES) a promising technique for food systems, including simple manufacturing equipment, a relatively low spinning cost, a wide variety of spinnable materials, and a mild process that is easily controlled, which allows continuous fabrication of ultrafine polymeric fibers at submicron or nanoscales without high temperatures or high pressures. This review briefly describes recent advances in the development of electrospun fibers for loading probiotics (PRB) by focusing on ES technology, its efficiency for loading PRB into fibers (viability, digestive stability, growth rate, release, thermal stability, and interactions of fibers with PRB), and the application of PRB-loaded fibers as active packaging (spoilage/microbial control, antioxidant effect, shelf life). Based on the literature reviewed, the incorporation of PRB into electrospun fibers is both feasible and functional. However, several studies have been limited to proof-of-principle experiments and the use of model biological products. It is necessary to conduct further research to establish the industrial applicability of PRB-loaded fibers, particularly in the fields of food and medicine.

Colon-targeted delivery of polyphenols: construction principles, targeting mechanisms and evaluation methods

Polyphenols have received considerable attention for their promotive effects on colonic health. However, polyphenols are mostly sensitive to harsh gastrointestinal environments, thus, must be protected. It is necessary to design and develop a colon-targeted delivery system to improve the stability, colon-targeting and bioavailability of polyphenols. This paper mainly introduces research on colon-targeted controlled release of polyphenols. The physiological features affecting the dissolution, release and absorption of polyphenol-loaded delivery systems in the colon are first discussed. Simultaneously, the types of colon-targeted carriers with different release mechanisms are described, and colon-targeting assessment models that have been studied so far and their advantages and limitations are summarized. Based on the current research on polyphenols colon-targeting, outlook and reflections are proposed, with the goal of inspiring strategic development of new colon-targeted therapeutics to ensure that the polyphenols reach the colon with complete bioactivity.

Enzyme-Triggered Intestine-Specific Targeting Adhesive Platform for Universal Oral Drug Delivery

Patient adherence to chronic therapies can be suboptimal, leading to poor therapeutic outcomes. Dosage forms that enable reduction in dosing frequency stand to improve patient adherence. Variation in gastrointestinal transit time, inter-individual differences in gastrointestinal physiology and differences in physicochemical properties of drugs represent challenges to the development of such systems. To this end, a small intestine-targeted drug delivery system is developed, where prolonged gastrointestinal retention and sustained release are achieved through tissue adhesion of drug pills mediated by an essential intestinal enzyme catalase. Here proof-of-concept pharmacokinetics is demonstrated in the swine model for two drugs, hydrophilic amoxicillin and hydrophobic levodopa. It is anticipated that this system can be applicable for many drugs with a diverse of physicochemical characteristics.

Bio-Inspired Muco-Adhesive Polymers for Drug Delivery Applications

Muco-adhesive drug delivery systems continue to be one of the most studied for controlled pharmacokinetics and pharmacodynamics. Briefly, muco-adhesive polymers, can be described as bio-polymers that adhere to the mucosal (mucus) surface layer, for an extended residency period of time at the site of application, by the help of interfacial forces resulting in improved drug delivery. When compared to traditional drug delivery systems, muco-adhesive carriers have the potential to enhance therapeutic performance and efficacy, locally and systematically, in oral, rectal, vaginal, amongst other routes. Yet, the achieving successful muco-adhesion in a novel polymeric drug delivery solution is a complex process involving key physico-chemico-mechanical parameters such as adsorption, wettability, polymer chain length, inter-penetration and cross-linking, to list a few. Hence, and in light of accruing progress, evidence and interest, during the last decade, this review aims to provide the reader with an overview of the theories, principles, properties, and underlying mechanisms of muco-adhesive polymers for pharmaceutics; from basics to design to characterization to optimization to evaluation to market. A special focus is devoted to recent advances incorporating bio-inspired polymers for designing controlled muco-adhesive drug delivery systems.

Characterization of an In Vitro/Ex Vivo Mucoadhesiveness Measurement Method of PVA Films

Transmucosal drug delivery systems can be an attractive alternative to conventional oral dosage forms such as tablets. There are numerous in vitro methods to estimate the behavior of mucoadhesive dosage forms in vivo. In this work, a tensile test system was used to measure the mucoadhesion of polyvinyl alcohol films. An in vitro screening of potential influencing variables was performed on biomimetic agar/mucin gels. Among the test device-specific factors, contact time and withdrawal speed were identified as influencing parameters. In addition, influencing factors such as the sample area, which showed a linear relationship in relation to the resulting work, and the liquid addition, which led to an abrupt decrease in adhesion, could be identified. The influence of tissue preparation was investigated in ex vivo experiments on porcine small intestinal tissue. It was found that lower values of F_max and W_ad were obtained on processed and fresh tissue than on processed and thawed tissue. Film adhesion on fresh, unprocessed tissue was lowest in most of the animals tested. Comparison of ex vivo measurements on porcine small intestinal tissue with in vitro measurements on agar/mucin gels illustrates the inter- and intra-individual variability of biological tissue.

A review of recent progress in improving the bioavailability of nutraceutical-loaded emulsions after oral intake

Increasing awareness of the health benefits of specific constituents in fruits, vegetables, cereals, and other whole foods has sparked a broader interest in the potential health benefits of nutraceuticals. Many nutraceuticals are hydrophobic substances, which means they must be encapsulated in colloidal delivery systems. Oil-in-water emulsions are one of the most widely used delivery systems for improving the bioavailability and bioactivity of these nutraceuticals. The composition and structure of emulsions can be designed to improve the water dispersibility, physicochemical stability, and bioavailability of the encapsulated nutraceuticals. The nature of the emulsion used influences the interfacial area and properties of the nutraceutical-loaded oil droplets in the gastrointestinal tract, which influences their digestion, as well as the bioaccessibility, metabolism, and absorption of the nutraceuticals. In this article, we review recent in vitro and in vivo studies on the utilization of emulsions to improve the bioavailability of nutraceuticals. The findings from this review should facilitate the design of more efficacious nutraceutical-loaded emulsions with increased bioactivity.

Redispersible 3D printed nanomedicines: An original application of the semisolid extrusion technique

Semisolid extrusion is a layer-by-layer 3D printing technique that produces objects from gels or pastes. This process can be carried out at room temperature, without using a light source, and has been explored in pharmaceutics in the last few years. In this regard, our group hypothesized its suitability for the production of three-dimensional (3D) printed nanomedicines containing drug-loaded organic nanocarriers. In this study, the original application of the semisolid extrusion was evaluated to produce redispersible 3D printed oral solid forms containing drug-loaded polymeric nanocapsules. A carboxymethyl cellulose hydrogel containing resveratrol and curcumin co-encapsulated in nanocapsules was prepared, and the nanocapsules did not change its complex viscosity and yield stress. Homogeneous and yellow cylindrical-shaped solid forms were printed, with a mean weight of 0.102 ± 0.015 g, a polyphenol content of approximately 160 μg/unit, disintegration time of <45 min, and recovery of the nanosized carriers. The polyphenols were completely released from the solid forms after 8 h, although part of them remained encapsulated in the nanocapsules. This study represents a proof of concept concerning the use of semisolid extrusion to produce 3D printed forms composed of polymeric nanocapsules in a one-step process. It proposes an original platform for the development of solid nanomedicines from liquid aqueous nanocapsule suspensions.

Encapsulation of probiotics: past, present and future

Background

Probiotics are live microbial supplements known for its health benefits. Consumption of probiotics reported to improve several health benefits including intestinal flora composition, resistance against pathogens. In the recent years, there is an increasing trend of probiotic-based food products in the market.

Main body

Probiotics cells are targeted to reach the large intestine, and the probiotics must survive through the acidic conditions of the gastric environment. It is recommended to formulate the probiotic bacteria in the range of 108–109 cfu/g for consumption and maintain the therapeutic efficacy of 106–107 cfu/g in the large intestine. During the gastrointestinal transit, the probiotics will drastically lose its viability in the gastric environment (pH 2). Maintaining cell viability until it reaches the large intestine remains challenging task. Encapsulating the probiotics cells with suitable wall material helps to sustain the survival of probiotics during industrial processing and in gastrointestinal transit. In the encapsulation process, cells are completely enclosed in the wall material, through different techniques including spray drying, freeze drying, extrusion, spray freeze drying, emulsification, etc. However, spray-drying and freeze-drying techniques are successfully used for the commercial formulation; thus, we limited to review those encapsulation techniques.

Short conclusions

The survival rate of spray-dried probiotics during simulated digestion mainly depends on the inlet air temperature, wall material and exposure in the GI condition. And fermentation, pH and freeze-drying time are the important process parameters for maintaining the viability of bacterial cells in the gastric condition. Improving the viability of probiotic cells during industrial processing and extending the cell viability during storage and digestion will be the main concern for successful commercialization.

Graphical abstract

Sequential loading of inclusion complex/nanoparticles improves the gastric retention of Vladimiriae Radix essential oil to promote the protection of acute gastric mucosal injury

The essential oil from Vladimiriae Radix (VEO) is a medicinal natural product with anti-ulcer activity. A novel gastroretentive drug delivery system was developed by preparing the hydroxypropyl-β-cyclodextrin (HP-β-CD) inclusion complex incorporated into chitosan nanoparticles (V-CD/NPs), to improve the bioavailability of VEO and its protective effect on gastric mucosa. The optimum preparation process of V-CD/NPs was obtained by Plackett-Burman and Box-Behnken response surface methodology. The resulting V-CD/NPs gained a suitable positive potential and small particle size, and showed stability in simulated gastric fluid, whose morphology and in vitro drug release profiles had a pH-sensitivity. Besides, V-CD/NPs was proved to strongly bind with mucin, and in vivo imaging revealed that it could be retained in the stomach for more than 8 h. The results of drug concentration in gastric tissues showed that the sequential loading of inclusion complex/nanoparticles promoted the local absorption of VEO in gastric tissues, which was favorable to reach the effective therapeutic concentration in the lesioned mucosa area. In comparison to VEO and V-CD, the callback effect of V-CD/NPs on 1L-1β, 1L-6, TNF-α, NF-κB, MDA and SOD was comparable to cimetidine, and V-CD/NPs outperformed in gastric mucosal protection. Therefore, the gastroretentive drug delivery system developed in our study effectively enhanced the anti-ulcer activity of VEO, which could be a promising strategy for the prevention and treatment of the acute gastric mucosal injury.

Lipid-Based Nanocarrier System for the Effective Delivery of Nutraceuticals

Nutraceuticals possess several health benefits and functions; however, most nutraceuticals are prone to degradation in the gastrointestinal environment and have poor bioavailability. Application of a novel carrier system is of increasing importance to overcome obstacles and provide efficient applicability. Lipid-based nanocarriers provide a large surface-to-mass ratio, enhanced intestinal absorption by solubilization in the intestinal milieu, intestinal lymphatic transport, and altering enterocyte-based transport. A critical overview of the current limitation, preparation, and application of lipid-based nanocarriers (liposomes and niosomes) and lipid nanoparticles (SLNs and NLCs) is discussed. Physical and gastrointestinal stability and bioavailability of nanoencapsulated nutraceuticals are considered as well.