Recent advances in oral delivery of macromolecular drugs and benefits of polymer conjugation

Exploring pectin-casein micelles as novel carriers for oral drug delivery of artesunate in the treatment of systemic lupus erythematosus

The oral route of administration is considered the optimal choice for treating chronic diseases due to its convenience and non-invasiveness, which can help prevent physical and mental harm to patients undergoing long-term treatment. However, challenges such as safety, gastrointestinal stability, and bioavailability of oral drugs often limit their effectiveness. Natural biomacromolecule micelles, known for their safety, stability, biocompatibility, and diverse functions, have emerged as promising carriers for oral treatment of chronic diseases like systemic lupus erythematosus (SLE) with fat-soluble drugs. This study introduces an innovative approach by developing an oral delivery system using chemically synthesized natural biomacromolecules to load artesunate for treating SLE. By synthesizing amphiphilic polymer micelles from pectin and casein through a carbodiimide reaction, a more stable structure is achieved. The hydrophobic core of these micelles encapsulates artesunate, resulting in the formation of an oral delivery system (PC-AS) with several advantages, including high drug loading and encapsulation efficiency, small particle size, negative potential, strong stability in the gastrointestinal tract, low toxicity and side effects, strong adhesion in the small intestine, and high bioavailability. These advantages facilitate efficient absorption of artesunate in the gastrointestinal tract, leading to improved bioavailability and effective alleviation of SLE-like symptoms in MRL/lpr mice. By utilizing chemically synthesized natural macromolecular micelles for delivering artesunate in the treatment of SLE, this study overcomes the oral barriers associated with the original drug and presents a novel solution for the long-term oral treatment of chronic diseases.

An organometallic swap strategy for bottlebrush polymer-protein conjugate synthesis

Polymer-protein bioconjugation offers a powerful strategy to alter the physical properties of proteins, and various synthetic polymer compositions and architectures have been investigated for this purpose. Nevertheless, conjugation of molecular bottlebrush polymers (BPs) to proteins remains an unsolved challenge due to the large size of BPs and a general lack of methods to transform the chain ends of BPs into functional groups suitable for bioconjugation. Here, we present a strategy to address this challenge in the context of BPs prepared by "graft-through" ring-opening metathesis polymerization (ROMP), one of the most powerful methods for BP synthesis. Quenching ROMP of PEGylated norbornene macromonomers with an activated enyne terminator facilitates the transformation of the BP Ru alkylidene chain ends into Pd oxidative addition complexes (OACs) for facile bioconjugation. This strategy is shown to be effective for the synthesis of two BP-protein conjugates (albumin and ERG), setting the stage for a new class of BP-protein conjugates for future therapeutic and imaging applications.

Fabrication and Characterization of Buccal Film Loaded Self-emulsifying Drug Delivery System containing Lysiphyllum strychnifolium Stem Extracts

Lysiphyllum strychnifolium has long been used as a popular herbal medicinal plant for treating fever and alcohol intoxication. This study aimed to prepare buccal film for L. strychnifolium stem extracts. These extracts were less soluble in water and were therefore loaded in self-emulsifying systems before being mixed into the film. Astilbin was selected as a chemical marker in L. strychnifolium stem extracts. Firstly, the L. strychnifolium stem extracts were entrapped in the self-emulsifying systems which were designed and optimized based on 3² factorial design. The optimal formulation was 0.60 g of surfactant-co-surfactant mixture (Tween^® 80 and polyethylene glycol 400 in the ratio of 7.5:1) and 0.40 g of caprylic/capric triglyceride. Secondly, the optimal self-emulsifying system was loaded in the polymeric film which consisted of polyvinyl alcohol blended with poloxamer 407 using glycerin as a plasticizer. The properties of the prepared buccal film were unchanged, and the film showed an amorphous state, indicating all ingredients might be completely dissolved in the film. The buccal film could be placed in direct contact with the mouth without oral mucosal irritation, and showed a smooth and homogeneous surface with a rough and compact cross-sectional morphology. Astilbin content in the buccal film was 61.39 ± 11.45 µg/cm². Astilbin was released from the buccal film while the permeation rate was low. The release mechanism was both swelling and diffusion, and followed anomalous or non-Fickian transfer. The permeability coefficient of the cumulative amount of astilbin permeated from buccal film was 1.0192 ± 0.1395 ×10^-3 cm/h. Thus, the buccal film can be prepared by using a self-emulsifying system for herbal applications and shows potential as a safe and convenient form of oral drug administration.

Stereomicroscope with Imaging Analysis: A Versatile Tool for Wetting, Gel Formation and Erosion Rate Determinations of Eutectic Effervescent Tablet

Wettability, gel formation and erosion behaviors could influence the drug release pattern of solid dosage forms. Typically, these parameters are evaluated using a variety of techniques. Nonetheless, there has been no previous research on versatile tool development for evaluating several tablet characteristics with a single tool. The aim of this study was to develop the versatile tool for measuring various physical properties of eutectic effervescent tablets and also investigate the relationship between these parameters with parameters from drug dissolution. Ibuprofen (IBU)-poloxamer 407 (P407) eutectic effervescent tablets were fabricated with a direct compression method. Their wetting properties, gel formation and erosion behaviors were investigated using a stereomicroscope with imaging analysis in terms of the liquid penetration distance, gel thickness and erosion boundary diameter, respectively. In addition, the dissolution rate (k) and disintegration time of eutectic effervescent tablets in 0.1 N HCl buffer pH 1.2 were also determined. Incorporation of P407 into the IBU tablet improved the tablet wetting properties with increasing liquid penetration distance under stereoscope. CO2 liberation from effervescent agents promoted tablet surface roughness from matrix erosion. The relationship between observed physical properties and disintegration and dissolution parameters suggested that the combination of erosion by effervescent agents and gel formation by P407 had a potential influence on dissolution enhancement of the formulation. Therefore, a developed stereomicroscope with an imaging analysis technique was exhibited as an alternative versatile tool for determining the wetting properties, gel formation and erosion behaviors of pharmaceutical solid dosage forms.

Nano Spray-Dried Drugs for Oral Administration: A Review

Spray drying is an important technology that is fast, simple, reproducible, and scalable. It has a wide application range, that is, in food, chemicals, and encapsulation of pharmaceuticals. The technology can be divided into conventional spray drying and nano spray drying. The key advantage of nano spray drying is the production of drug-loaded nanosized particles for various drug delivery applications. The recent developments in nano spray dryer technology and the market launch of the Nano Spray Dryer B-90 by Büchi Labortechnik AG in 2009 enabled the production of submicron spray-dried particles. This review focuses on nanosized drug delivery systems intended for oral administration produced by nano spray drying. First, the nano spray drying concept, the basic technologies implemented in the equipment, and the effects of the various process parameters on the final dry submicron powder properties are presented. Then, the topics of new formulation strategies of oral drugs are highlighted with examples that have entered the research literature in recent years. Next, the subjects of direct conversion of poorly water-soluble drugs, encapsulation of drugs, and drying of preformed nanoparticles are considered. Finally, topics such as morphology, particle size, size distribution, surface analysis, bioavailability, drug release, release kinetics, and solid-state characterization (by differential scanning calorimetry, X-ray diffraction, Fourier transform infrared spectroscopy, nuclear magnetic resonance) of oral drug delivery systems produced by nano spray drying are discussed. The review attempts to provide a comprehensive knowledge base with current literature and foresight to researchers working in the field of pharmaceutical technology and nanotechnology and especially in the field of nano spray drying.

Recent advances in mechanical force-assisted transdermal delivery of macromolecular drugs

The transdermal delivery of macromolecular drugs has become one of the focused topics in pharmaceutical research since it enables highly specific and effective delivery, while avoiding the pain and needle phobia associated with injection, or incidences like drug degradation and low bioavailability of oral administration. However, the passive absorption of macromolecular drugs via skin is highly restricted by the stratum corneum owing to high molecular weight. Therefore, various strategies have been extensively developed and conducted to facilitate the transdermal delivery of macromolecular drugs, among which, mechanical force-assisted techniques occupy dominant positions. Such techniques include ultrasound, needle-free jet injection, temporary pressure and microneedles. In this review, we focus on recent transdermal enhancing strategies utilizing mechanical force, and summarize their mechanisms, advantages, limitations and clinical applications respectively.

Low molecular weight chitosan-cyanocobalamin nanoparticles for controlled delivery of ciprofloxacin: Preparation and evaluation

This study was carried out to project a safe nano-drug carrier composed of chitosan and cyanocobalamin (CNCbl) to improve oral delivery of ciprofloxacin hydrochloride (CIP). CIP is classified in class IV of the biopharmaceutical classification system with low solubility and permeabilityA, so it has some problems if given orally. Novel conjugate of low molecular weight chitosan, as a natural biopolymer, and CNCbl was synthesized, and then drug loading and in-vitro drug release were assessed. The loading of CIP was optimized by the Design-Expert software and the central composite design method, and that the optimal drug loading efficiency (57%) was obtained via analysis of variance (ANOVA). In-vitro drug release studies showed controlled release patterns in two various conditions, namely phosphate buffer saline (pH = 7.4) and 0.1 N HCl. Functionalized nano-drug-loaded carrier showed cytotoxicity as much as that of free drug, particle size less than 100 nm as well as positive zeta potential. Due to the beneficial properties of the chitosan-based drug carrier and the suitable features of the CIP-loaded carrier, this chitosan-based nano-drug delivery system can be regarded as an ideal candidate for oral delivery of the CIP as a drug model.

Eutectic mixtures as an approach to enhance solubility, dissolution rate and oral bioavailability of poorly water-soluble drugs

Eutectic mixtures have been known for a long time in the pharmaceutical field. However, its potential as a system to improve the solubility and dissolution of poorly water-soluble drugs remains little explored. Studies involving the microstructural characterization and the preparation of solid dosage forms containing eutectic mixtures are also an issue to be developed. Recently, the number of studies involving the preparation of eutectic mixtures to improve the solubility and oral bioavailability of poorly soluble drugs has increased considerably, including drug-carrier and drug-drug mixtures. In this review is discussed the potential of eutectic mixtures as an alternative pharmaceutical solid system to enhance drugs solubility, dissolution rate or oral bioavailability. Different aspects like history, physico-chemical, microstructural properties, preparation methods, mechanisms involved in solubility/dissolution enhancement, techniques for solid state characterization, in vivo studies, advantages, limitations and formulation perspective are also discussed.

Perspectives of Molecularly Imprinted Polymer-Based Drug Delivery Systems in Cancer Therapy

Despite the considerable effort made in the past decades, multiple aspects of cancer management remain a challenge for the scientific community. The severe toxicity and poor bioavailability of conventional chemotherapeutics, and the multidrug resistance have turned the attention of researchers towards the quest of drug carriers engineered to offer an efficient, localized, temporized, and doze-controlled delivery of antitumor agents of proven clinical value. Molecular imprinting of chemotherapeutics is very appealing in the design of drug delivery systems since the specific and selective binding sites created within the polymeric matrix turn these complex structures into value-added carriers with tunable features, notably high loading capacity, and a good control of payload release. Our work aims to summarize the present state-of-the art of molecularly imprinted polymer-based drug delivery systems developed for anticancer therapy, with emphasis on the particularities of the chemotherapeutics’ release and with a critical assessment of the current challenges and future perspectives of these unique drug carriers.

Engineering Strategies for Oral Therapeutic Enzymes to Enhance Their Stability and Activity

Oral application of therapeutic enzymes is a promising and non-invasive administration that improves patient compliance. However, the gastrointestinal tract poses several challenges to the oral delivery of proteins, including harsh pH conditions and digestive proteases. A promising way to stabilise enzymes during their gastrointestinal route is by modification with polymers that can provide both steric shielding and selective interaction in different digestive compartments. We give an overview of modification technologies for oral enzymes ranging from functionalisation of native proteins, to site-specific mutation and protein-polymer engineering. We specifically focus on enzymes that are active directly in the gastrointestinal lumen and not systemically absorbed. In addition, we discuss examples of microparticle and nanoparticle encapsulated enzymes for improved oral delivery. The modification of orally administered enzymes offers a broad chemical variability and may be a promising tool for enhancing their gastrointestinal stability.

Cyclodextrin/chitosan nanoparticles for oral ovalbumin delivery: Preparation, characterization and intestinal mucosal immunity in mice

A novel oral protein delivery system with enhanced intestinal penetration and improved antigen stability based on chitosan (CS) nanoparticles and antigen-cyclodextrin (CD) inclusion complex was prepared by a precipitation/coacervation method. Ovalbumin (OVA) as a model antigen was firstly encapsulated by cyclodextrin, either β-cyclodextrin (β-CD) or carboxymethyl-hydroxypropyl-β-cyclodextrin (CM-HP-β-CD) and formed OVA-CD inclusion complexes, which were then loaded to chitosan nanoparticles to form OVA loaded β-CD/CS or CM-HP-β-CD/CS nanoparticles with uniform particle size (836.3 and 779.2 nm, respectively) and improved OVA loading efficiency (27.6% and 20.4%, respectively). In vitro drug release studies mimicking oral delivery condition of OVA loaded CD/CS nanoparticles showed low initial releases at pH 1.2 for 2 h less than 3.0% and a delayed release which was below to 30% at pH 6.8 for further 72 h. More importantly, after oral administration of OVA loaded β-CD/CS nanoparticles to Balb/c mice, OVA-specific sIgA levels in jejunum of OVA loaded β-CD/CS nanoparticles were 3.6-fold and 1.9-fold higher than that of OVA solution and OVA loaded chitosan nanoparticles, respectively. In vivo evaluation results showed that OVA loaded CD/CS nanoparticles could enhance its efficacy for inducing intestinal mucosal immune response. In conclusion, our data suggested that CD/CS nanoparticles could serve as a promising antigen-delivery system for oral vaccination.

Extracellular vesicles protect glucuronidase model enzymes during freeze-drying

Extracellular vesicles (EVs) are natural nanoparticles that play important roles in intercellular communication and are increasingly studied for biosignalling, pathogenesis and therapy. Nevertheless, little is known about optimal conditions for their transfer and storage, and the potential impact on preserving EV-loaded cargoes. We present the first comprehensive stability assessment of different widely available types of EVs during various storage conditions including -80 °C, 4 °C, room temperature, and freeze-drying (lyophilisation). Lyophilisation of EVs would allow easy handling at room temperature and thus significantly enhance their expanded investigation. A model enzyme, β-glucuronidase, was loaded into different types of EVs derived from mesenchymal stem cells, endothelial cells and cancer cells. Using asymmetric flow field-flow fractionation we proved that the model enzyme is indeed stably encapsulated into EVs. When assessing enzyme activity as indicator for EV stability, and in comparison to liposomes, we show that EVs are intrinsically stable during lyophilisation, an effect further enhanced by cryoprotectants. Our findings provide new insight for exploring lyophilisation as a novel storage modality and we create an important basis for standardised and advanced EV applications in biomedical research.

The molecularly imprinted polymer essentials: curation of anticancer, ophthalmic, and projected gene therapy drug delivery systems

The development of polymeric materials as drug delivery systems has advanced from systems that rely on classical passive targeting to carriers that can sustain the precisely controlled release of payloads upon physicochemical triggers in desired microenvironment. Molecularly imprinted polymers (MIP), materials designed to capture specific molecules based on their molecular shape and charge distribution, are attractive candidates for fulfilling these purposes. In particular, drug-imprinted polymers coupled with active targeting mechanisms have been explored as potential drug delivery systems. In this review, we have curated important recent efforts in the development of drug-imprinted polymers in a variety of clinical applications, especially oncology and ophthalmology. MIP possesses properties that may complement the traditional delivery systems of these two disciplines, such as passive enhanced permeability and retention effect (EPR) in cancer tumors, and passive drug diffusion in delivering ophthalmic therapeutics. Furthermore, the prospects of MIP integration with the emerging gene therapies will be discussed.

Biogenic and Biomimetic Carriers as Versatile Transporters To Treat Infections

Biogenic and biomimetic therapeutics are a relatively new class of systems that are of physiological origin and/or take advantage of natural pathways or aim at mimicking these to improve selective interaction with target tissue. The number of biogenic and bioengineered avenues for drug therapy and diagnostics has multiplied over the past years for many applications, indicating the high expectations associated with this biological route. Nevertheless, the use of "bio"-related approaches for treating or diagnosing infectious diseases is still rare. Given that infectious diseases, in particular bacterial resistances, are seriously on the rise, there is an urgent need to take advantage of biogenic and bioengineered systems to target these challenges. In this manuscript, we first give a definition of the various "bio" terms, including biogenic, biomimetic, bioinspired, and bioengineered and we highlight them using tangible applications in the field of infectious diseases. Our examples cover cell-derived systems, including bioengineered bacteria, virus-like particles, and different cell-mimetics. Moreover, we discuss natural and bioengineered particles such as extracellular vesicles from mammalian and bacterial sources and liposomes. A concluding section outlines the potential for biomaterial-related avenues to overcome challenges associated with difficult-to-treat infections. We critically discuss benefits and risks for these applications and give an outlook on the future of biogenic engineering.

Engineering Extracellular Vesicles with the Tools of Enzyme Prodrug Therapy

Extracellular vesicles (EVs) have recently gained significant attention as important mediators of intercellular communication, potential drug carriers, and disease biomarkers. These natural cell-derived nanoparticles are postulated to be biocompatible, stable under physiological conditions, and to show reduced immunogenicity as compared to other synthetic nanoparticles. Although initial clinical trials are ongoing, the use of EVs for therapeutic applications may be limited due to undesired off-target activity and potential "dilution effects" upon systemic administration which may affect their ability to reach their target tissues. To fully exploit their therapeutic potential, EVs are embedded into implantable biomaterials designed to achieve local delivery of therapeutics taking advantage of enzyme prodrug therapy (EPT). In this first application of EVs for an EPT approach, EVs are used as smart carriers for stabilizing enzymes in a hydrogel for local controlled conversion of benign prodrugs to active antiinflammatory compounds. It is shown that the natural EVs' antiinflammatory potential is comparable or superior to synthetic carriers, in particular upon repeated long-term incubations and in different macrophage models of inflammation. Moreover, density-dependent color scanning electron microscopy imaging of EVs in a hydrogel is presented herein, an impactful tool for further understanding EVs in biological settings.

Fenofibrate Nanocrystals Embedded in Oral Strip-Films for Bioavailability Enhancement

The aim of the present study was to make a fenofibrate (FNB) nanocrystal (NC) by wet media milling, characterizations and formulates into oral strip-films (OSFs). Mechanical properties, redispersion study, and solid-state characterizations results suggested that reduction of drug crystal size at nanoscale and incorporation into OSFs does not affect the solid-state properties of the drug. In vitro dissolution kinetics showed enhanced dissolution rate was easily manipulated by changing the thickness of the OSF. In situ UV-imaging was used to monitor drug dissolution qualitatively and quantitatively in real time. Results confirm that the intrinsic dissolution rates and surface drug concentration measured with this device were in agreement with the USP-IV dissolution profiles. In vivo pharmacokinetics in rabbits showed a significant difference in the pharmacokinetics parameter (1.4 fold increase bioavailability) of FNB NC-loaded OSFs as compared to the marketed formulation “Tricor” and as-received (pristine) drug. This approach of drug nanocrystallization and incorporation into OSFs may have significant applications in cost-effective tools for bioavailability enhancement of FNB.