Mucoadhesion and drug permeability of free mixed films of pectin and chitosan: An in vitro and ex vivo study

Development of an Antiviral Ion-Activated In Situ Gel Containing 18β-Glycyrrhetinic Acid: A Promising Alternative against Respiratory Syncytial Virus

The human respiratory syncytial virus (hRSV) is a major cause of serious lower respiratory infections and poses a considerable risk to public health globally. Only a few treatments are currently used to treat RSV infections, and there is no RSV vaccination. Therefore, the need for clinically applicable, affordable, and safe RSV prevention and treatment solutions is urgent. In this study, an ion-activated in situ gelling formulation containing the broad-spectrum antiviral 18β-glycyrrhetinic acid (GA) was developed for its antiviral effect on RSV. In this context, pH, mechanical characteristics, ex vivo mucoadhesive strength, in vitro drug release pattern, sprayability, drug content, and stability were all examined. Rheological characteristics were also tested using in vitro gelation capacity and rheological synergism tests. Finally, the cytotoxic and antiviral activities of the optimized in situ gelling formulation on RSV cultured in the human laryngeal epidermoid carcinoma (HEp-2) cell line were evaluated. In conclusion, the optimized formulation prepared with a combination of 0.5% w/w gellan gum and 0.5% w/w sodium carboxymethylcellulose demonstrated good gelation capacity and sprayability (weight deviation between the first day of the experiment (T0) and the last day of the experiment (T14) was 0.34%), desired rheological synergism (mucoadhesive force (Fb): 9.53 Pa), mechanical characteristics (adhesiveness: 0.300 ± 0.05 mJ), ex vivo bioadhesion force (19.67 ± 1.90 g), drug content uniformity (RSD%: 0.494), and sustained drug release over a period of 6 h (24.56% ± 0.49). The optimized formulation demonstrated strong anti-hRSV activity (simultaneous half maximal effective concentration (EC50) = 0.05 µg/mL; selectivity index (SI) = 306; pre-infection EC50 = 0.154 µg/mL; SI = 100), which was significantly higher than that of ribavirin (EC50 = 4.189 µg/mL; SI = 28) used as a positive control against hRSV, according to the results of the antiviral activity test. In conclusion, this study showed that nasal in situ gelling spray can prevent viral infection and replication by directly inhibiting viral entry or modulating viral replication.

Texture analysis – a versatile tool for pharmaceutical evaluation of solid oral dosage forms

In the past few decades, texture analysis (TA) has gained importance as a valuable method for the characterization of solid oral dosage forms. As a result, an increasing number of scientific publications describe the textural methods that evaluate the extremely diverse category of solid pharmaceutical products. Within the current work, the use of texture analysis in the characterization of solid oral dosage forms is summarised with a focus on the evaluation of intermediate and finished oral pharmaceutical products. Several texture methods are reviewed regarding the applications in mechanical characterization, and mucoadhesion testing, but also in estimating the disintegration time and in vivo specific features of oral dosage forms. As there are no pharmacopoeial standards for pharmaceutical products tested through texture analysis, and there are important differences between reported results due to different experimental conditions, the choice of testing protocol and parameters is challenging. Thereby, this work aims to guide the research scientists and quality assurance professionals involved in different stages of drug development into the selection of optimal texture methodologies depending on the product characteristics and quality control needs.

Buccal films: A review of therapeutic opportunities, formulations & relevant evaluation approaches

The potential of the mucoadhesive film technology is hard to ignore, owing to perceived superior patient acceptability versus buccal tablets, and significant therapeutic opportunities compared to conventional oral drug delivery systems, especially for those who suffer from dysphagia. In spite of this, current translation from published literature into the commercial marketplace is virtually non-existent, with no authorised mucoadhesive buccal films available in the UK and very few available in the USA. This review seeks to provide an overview of the mucoadhesive buccal film technology and identify key areas upon which to focus scientific efforts to facilitate the wider adoption of this patient-centric dosage form. Several indications and opportunities for development were identified, while discussing the patient-related factors influencing the use of these dosage forms. In addition, an overview of the technologies behind the manufacturing of these films was provided, highlighting manufacturing methods like solvent casting, hot melt extrusion, inkjet printing and three-dimensional printing. Over thirty mucoadhesive polymers were identified as being used in film formulations, with details surrounding their mucoadhesive capabilities as well as their inclusion alongside other key formulation constituents provided. Lastly, the importance of physiologically relevant in vitro evaluation methodologies was emphasised, which seek to improve in vivo correlations, potentially leading to better translation of mucoadhesive buccal films from the literature into the commercial marketplace.

Bacterial cellulose adhesive patches designed for soft mucosal interfaces

The wet environment in the oral cavity is challenging for topical disease management approaches. The compromised material properties leading to weak adhesion and short retention (<8 h) in such environment result in frequent reapplication of the therapeutics. Composites of bacterial cellulose (BC) and carbene-based bioadhesives attempt to address these shortcomings. Previous designs comprised of aqueous formulations. The current design, for the first time, presents dry, shelf-stable cellulose patches for convenient ready-to-use application. The dry patches simultaneously remove tissue surface hydration while retaining carbene-based photocuring and offers on-demand adhesion. The dry patch prototypes are optimized by controlling BC/adhesive mole ratios and dehydration technique. The adhesion strength is higher than commercial denture adhesives on soft mucosal tissues. The structural integrity is maintained for a minimum of 7 days in aqueous environment. The patches act as selective nanoporous barrier against bacteria while allowing permeation of proteins. The results support the application of BC-based adhesive patches as a flexible platform for wound dressings, drug depots, or combination thereof.

Formulation strategies to improve the efficacy of intestinal permeation enhancers. Adv Drug Deliv Rev 2021;177:113925. [PMID: 34418495 DOI: 10.1016/j.addr.2021.113925]

The use of chemical permeation enhancers (PEs) is the most widely tested approach to improve oral absorption of low permeability active agents, as represented by peptides. Several hundred PEs increase intestinal permeability in preclinical bioassays, yet few have progressed to clinical testing and, of those, only incremental increases in oral bioavailability (BA) have been observed. Still, average BA values of ~1% were sufficient for two recent FDA approvals of semaglutide and octreotide oral formulations. PEs are typically screened in static in vitro and ex-vivo models where co-presentation of active agent and PE in high concentrations allows the PE to alter barrier integrity with sufficient contact time to promote flux across the intestinal epithelium. The capacity to maintain high concentrations of co-presented agents at the epithelium is not reached by standard oral dosage forms in the upper GI tract in vivo due to dilution, interference from luminal components, fast intestinal transit, and possible absorption of the PE per se. The PE-based formulations that have been assessed in clinical trials in either immediate-release or enteric-coated solid dosage forms produce low and variable oral BA due to these uncontrollable physiological factors. For PEs to appreciably increase intestinal permeability from oral dosage forms in vivo, strategies must facilitate co-presentation of PE and active agent at the epithelium for a sustained period at the required concentrations. Focusing on peptides as examples of a macromolecule class, we review physiological impediments to optimal luminal presentation, discuss the efficacy of current PE-based oral dosage forms, and suggest strategies that might be used to improve them.

Solid lipid nanoparticle-loaded mucoadhesive buccal films - Critical quality attributes and in vitro safety & efficacy

The objective of this work was to develop and characterize solid lipid nanoparticle (SLN)-loaded mucoadhesive films to reveal their potential as successful drug formulations. SLNs based on lipid (Lipoid S100) and surfactant (polysorbate 80) were prepared using the solvent-injection method, and their properties examined using experimental designs. Further, the marker coumarin 6 (C6) was solubilized in the particles as a model for a lipophilic drug. Lipid and surfactant concentrations influenced the particle size, while C6 had minor impact. The particle size distribution was narrow and the storage stability satisfactory for 4 months (4 ℃). The incorporation of the nanoparticles into a film matrix consisting of HPMC and glycerol, increased film thickness and flexibility, and slightly decreased the mechanical strength. The mucin interaction and disintegration time of the films were unimpaired. Film uniformity was satisfactory. Solubilisation in SLNs reduced the rate and extent of permeation of C6 through a monolayer of mucus-producing HT29-MTX cells. When the particles were incorporated into the mucoadhesive film, this effect was compensated for. In conclusion, this project was a first step in the successful development of an SLN-loaded mucoadhesive film formulation and served its purpose in revealing the formulation's uniformity, mucoadhesiveness and biocompatibility.

Dual Oral Tissue Adhesive Nanofiber Membranes for pH-Responsive Delivery of Antimicrobial Peptides

Bioadhesive membranes with controllable and reversible underwater adhesion are desirable for several biomedical applications ranging from biosensing, drug/therapeutic delivery, and tissue regeneration. Here, we present dual soft mucosal and hard bone/enamel tissue adhesive nanofiber membranes composed of chitosan and pectin derivatives for pH-controlled delivery of antimicrobial peptides (AMPs) in the oral cavity. Ex vivo testing with porcine esophagus (soft mucosal mimic) indicated a 2-fold increase in the mucoadhesion of chitosan membranes with 0.05 wt % oxidized pectin coating, while the uncoated membranes exhibited 3-4-fold stronger adhesion to hydroxyapatite discs (enamel/hard bone mimic) compared to the coated membranes. The former is attributed to a synergistic interaction of surface nanofiber topography, intermolecular hydrogen bonding, and aldehyde-amine chemistry between surface polar groups and mucosal proteins, while the latter may arise from electrostatic interactions between cationic amines (-NH₃⁺) in chitosan and anionic phosphates (-PO₄^3-) in hydroxyapatite. Further, the dual hard-soft oral tissue adhesive nanofiber membranes loaded with cationic amphipathic AMPs (D-GL13K and IDR-1018) elicited pH-responsive AMP delivery and antimicrobial action comparable to chlorhexidine (CHX) against oral streptococci. Concurrently, the AMP loaded membranes were cytocompatible to both soft epithelial tissue-derived human oral keratinocytes and hard calvarial murine pre-osteoblast cells. We envision these membranes to function as adhesive gingival grafts and guided bone regeneration (GBR) membranes at the hard-soft tissue interface while simultaneously protecting against oral infections.

How Can Biomolecules Improve Mucoadhesion of Oral Insulin? A Comprehensive Insight using Ex-Vivo, In Silico, and In Vivo Models

Currently, insulin can only be administered through the subcutaneous route. Due to the flaws associated with this route, it is of interest to orally deliver this drug. However, insulin delivered orally has several barriers to overcome as it is degraded by the stomach’s low pH, enzymatic content, and poor absorption in the gastrointestinal tract. Polymers with marine source like chitosan are commonly used in nanotechnology and drug delivery due to their biocompatibility and special features. This work focuses on the preparation and characterization of mucoadhesive insulin-loaded polymeric nanoparticles. Results showed a suitable mean size for oral administration (<600 nm by dynamic laser scattering), spherical shape, encapsulation efficiency (59.8%), and high recovery yield (80.6%). Circular dichroism spectroscopy demonstrated that protein retained its secondary structure after encapsulation. Moreover, the mucoadhesive potential of the nanoparticles was assessed in silico and the results, corroborated with ex-vivo experiments, showed that using chitosan strongly increases mucoadhesion. Besides, in vitro and in vivo safety assessment of the final formulation were performed, showing no toxicity. Lastly, the insulin-loaded nanoparticles were effective in reducing diabetic rats’ glycemia. Overall, the coating of insulin-loaded nanoparticles with chitosan represents a potentially safe and promising approach to protect insulin and enhance peroral delivery.

Salt reduction in liquid/semi-solid foods based on the mucopenetration ability of gum arabic

Gum arabic enhances the saltiness perception of liquid/semi-solid foods via a mucopenetration effect.

Development of a bioadhesive nanoformulation with Glycyrrhiza glabra L. extract against Candida albicans

Glycyrrhiza glabra L. is considered an important source of bioactive compounds. This study aimed at the development of an efficient solution for the treatment of oral candidiasis. Several extracts of Glycyrrhiza glabra L. were prepared using different solvents and their potential in vitro antifungal activity was assessed. Ethanolic extracts showed the most promising results against C. albicans. This extract was incorporated into mucoadhesive nanoparticles (PLA, PLGA and alginate), which were further included in an oral gel, an oral film and a toothpaste, respectively. The results showed that nanoparticles were successfully produced, presenting a mean size among 100-900 nm with high encapsulation efficiency. In vitro studies showed that the most bioadhesive formulation was the oral film with extract-loaded PLGA nanoparticles, followed by the toothpaste with extract-loaded alginate nanoparticles and the oral gel with extract-loaded PLA nanoparticles.

Mucoadhesive assessment of different antifungal nanoformulations

Oral candidiasis is an important opportunistic fungal infection and polyenes and azoles are still the most used antifungal agents. However, the oral absorption resulting from most available treatments is generally poor and, consequently, a very high frequency of administrations of antifungal agents is strongly required. Therefore, the major challenge is to improve the retention of the antifungal agents in buccal mucosa, and the encapsulation into mucoadhesive systems may be considered as a possible strategy to achieve this objective. Three types of mucoadhesive polymeric nanoparticles (polylactic acid (PLA), polylactic-co-glycolic acid (PLGA) and alginate) were prepared using nystatin as model drug. The drug-loaded nanoparticles were then included in toothpaste, oral gel and oral films, respectively. The results demonstrated that the loaded nanoparticles were successfully produced, presenting a mean size between 300-900 nm and with a negative surface charge. Also, the determination of the encapsulation efficiency of all nanoparticles showed values above 70%. In terms of the in vitro mucoadhesion, the best formulation was the oral film loaded with the PLGA nanoparticles followed by the oral gel with PLA nanoparticles and thirdly the toothpaste with alginate nanoparticles. This was confirmed in an in vitro rinsing model with mucus producing HT29-MTX cells, where the percentage of nystatin retained to the cells after 40 min of simulated saliva flow was between 10-27% when formulations were used and only 4% for free nystatin. Further studies will include in vivo testing using animal models.

Recent insights in the use of nanocarriers for the oral delivery of bioactive proteins and peptides

Bioactive proteins and peptides have been used with either prophylactic or therapeutic purposes, presenting inherent advantages as high specificity and biocompatibility. Nanocarriers play an important role in the stabilization of proteins and peptides, offering enhanced buccal permeation and protection while crossing the gastrointestinal tract. Moreover, preparation of nanoparticles as oral delivery systems for proteins/peptides may include tailored formulation along with functionalization aiming bioavailability enhancement of carried proteins or peptides. Oral delivery systems, namely buccal delivery systems, represent an interesting alternative route to parenteric delivery systems to carry proteins and peptides, resulting in higher comfort of administration and, therefore, compliance to treatment. This paper outlines an extensive overview of the existing publications on proteins/peptides oral nanocarriers delivery systems, with special focus on buccal route. Manufacturing aspects of most commonly used nanoparticles for oral delivery (e.g. polymeric nanoparticles using synthetic or natural polymers and lipid nanoparticles) advantages and limitations and potential applications of nanoparticles as proteins/peptides delivery systems will also be thoroughly addressed.

Studies of chitosan/pectin complexes exposed to UV radiation

Chitosan and pectin form complexes owing to electrostatic interactions between positively charged amino groups in chitosan and negatively charged carboxylate groups in pectin, which was confirmed by ATR-FTIR spectroscopy and contact angle measurements. Moreover, the formation of these complexes might be associated with the loss of the biopolymers ordering, which resulted in higher surface roughness and lower thermal stability of the complexes in comparison to those of homopolymers. UV rays, used as a sterilizing agent, caused a moderate increase in the surface polarity of the complexes. Roughness parameters of these samples changed irregularly after irradiation, and their thermal stability was slightly affected by UV rays. The results indicated that the complexes studied appeared to present resistance to UV action higher than homopolymers, which is a desirable property in medical or pharmaceutical applications.

Development and characterization of a mucoadhesive sublingual formulation for pain control: extemporaneous oxycodone films in personalized therapy

OBJECTIVE

The aim of this work was the development of mucoadhesive sublingual films, prepared using a casting method, for the administration of oxycodone.

MATERIALS AND METHODS

A solvent casting method was employed to prepare the mucoadhesive films. A calibrated pipette was used to deposit single aliquots of different polymeric solutions on a polystyrene plate lid. Among the various tested polymers, hydroxypropylcellulose at low and medium molecular weight (HPC) and pectin at two different degrees of esterification (PC) were chosen for preparing solutions with good casting properties, capable of producing films suitable for mucosal application.

RESULTS AND DISCUSSION

The obtained films showed excellent drug content uniformity and stability and rapid drug release, which, at 8 min, ranged from 60% to 80%. All films presented satisfactory mucoadhesive and mechanical properties, also confirmed by a test on healthy volunteers, who did not experience irritation or mucosa damages. Pectin films based on pectin at lower degrees of esterification have been further evaluated to study the influence of two different amounts of drug on the physicochemical properties of the formulation. A slight reduction in elasticity has been observed in films containing a higher drug dose; nevertheless, the formulation maintained satisfactory flexibility and resistance to elongation.

CONCLUSIONS

HPC and PC sublingual films, obtained by a simple casting method, could be proposed to realize personalized hospital pharmacy preparations on a small scale.

Development and Evaluation of Biodegradable Chitosan Films of Metronidazole and Levofloxacin for the Management of Periodontitis

Metronidazole (MZ) and levofloxacin (LF) are widely employed for treatment of periodontitis, but high oral dose and resistance development after long-term oral administration limit their use. The aim of this study was to alleviate shortcomings in the treatment of periodontitis by fabrication of intrapocket, biodegradable films of chitosan (CS) loaded with MZ and LF meant for inserting into periodontal pockets to treat infections. The films were developed by solvent casting technique using propylene glycol as plasticizer and glutaraldehyde as crosslinking agent. Their physical characteristics, such as drug content, surface pH, swelling index, and folding endurance, exhibited results within limit. Further, FTIR and DSC studies revealed stability of films and compatibility between drugs and excipients. SEM images of films showed the presence of free drug particles on the surface causing burst effect. In vitro release in McIlvaine buffer pH 6.6 was of sustained nature assisted by the burst effect. CS and crosslinking agent concentrations negatively affected drug release and positively affected T₉₀ (time for releasing 90% of the drug) due to altered matrix density. In contrast, the plasticizer concentration increases membrane permeability and hence increased drug release, lowering T₉₀. Crosslinked films demonstrated sustained release up to 7 days. The antibacterial efficacy of films was tested on Staphylococcus aureus and Escherichia coli, indicating good antibacterial activity. Clinical trials on patients proved the therapeutic efficacy of the films by a significant (p < 0.05) decrease in the clinical markers of periodontitis, i.e. gingival index, plaque index and pocket depth. Conclusively, the films of MZ and LF were successful tools for the management of periodontitis.

In vitro oral drug permeation models: the importance of taking physiological and physico-chemical factors into consideration

INTRODUCTION

The assessment of intestinal membrane permeability properties of new chemical entities is a crucial step in the drug discovery and development process and a variety of in vitro models, methods and techniques are available to estimate the extent of oral drug absorption in humans. However, variations in certain physiological and physico-chemical factors are often not reflected in the results and the complex dynamic interplay between these factors is sometimes oversimplified with in vitro models. Areas covered: In vitro models to evaluate drug pharmacokinetics are briefly outlined, while both physiological and physico-chemical factors that may have an influence on these techniques are critically reviewed. The shortcomings identified for some of the in vitro techniques are discussed in conjunction with novel ways to improve and thereby overcome some challenges. Expert opinion: Although conventional in vitro methods and theories are used as basic guidelines to predict drug absorption, critical evaluations have identified some shortcomings. Advancements in technology have made it possible to investigate and understand the role of physiological and physico-chemical factors in drug delivery more clearly, which can be used to improve and refine the techniques to more closely mimic the in vivo environment.

Functionalized Polymers for Enhance Oral Bioavailability of Sensitive Molecules

Currently, many sensitive molecules have been studied for effective oral administration. These substances are biologically active compounds that mainly suffer early degradation in the gastrointestinal tract (GIT) and physicochemical instability, inactivation and poor solubility and permeability. The sensibility of the biomolecules has limited their oral administration in the body and today is an important research topic to achieve desired effects in medicine field. Under this perspective, various enhancement approaches have been studied as alternatives to increase their oral bioavailability. Some of these strategies include functionalized polymers to provide specific useful benefits as protection to the intestinal tract by preventing its degradation by stomach enzymes, to increase their absorption, permeability, stability, and to make a proper release in the GIT. Due to specific chemical groups, shapes and sizes, morphologies, mechanical properties, and degradation, recent advances in functionalized polymers have opened the door to great possibilities to improve the physicochemical characteristics of these biopharmaceuticals. Today, many biomolecules are found in basic studies, preclinical steps, and others are late stage clinical development. This review summarizes the contribution of functionalized polymers to enhance oral bioavailability of sensitive molecules and their application status in medicine for different diseases. Future trends of these polymers and their possible uses to achieve different formulation goals for oral delivery are also covered in this manuscript.

Fabrication, gastromucoadhesivity, swelling, and degradation of zein-chitosan composite ultrafine fibers

Fabrication, via electrospinning, and characterization of an ultrafine structure architected from a blend of hydrophobic zein and hydrophilic chitosan (CS) were conducted. Poly(ethylene oxide) (PEO) and nonionic surfactant, namely, Tween 40, were employed to improve the electrospinnability of the blend, while ethanol was used as a solvent for zein. The effects of ethanol (EtOH) concentration (85% and 90%) and ratio of zein/PEO/CS (95/2.5/2.5 and 87.5/10/2.5) on the fiber morphology as well as gastromucoadhesivity against porcine stomach mucosa were then investigated; polymer-mucosa adhesion was also investigated via Fourier-transform infrared spectroscopy. Swelling and degradation of the composite ultrafine fibers were investigated under 2 simulated gastric conditions, namely, at pH 2 without pepsin and at pH 1.2 with pepsin. Using 85% EtOH as a solvent for zein resulted in a spider-web-like morphology; the maximum detachment force (MDF), which is an indirect indicator of the gastromucoadhesivity was nevertheless higher. Zein-based ultrafine fibers exhibited higher MDF than the zein-PEO-CS composite; however, the cohesiveness of the composite fibers was higher. FTIR spectroscopic results indicated molecular interactions between the composite fibers and mucin functional groups. Swelling of the composite ultrafine fibers in simulated gastric fluid (SGF) at pH 2 without pepsin was not different from that in SGF at pH 1.2 with pepsin. Nevertheless, degradation of the composite fibers in SGF at pH 2 without pepsin was much less than that in SGF at pH 1.2 with pepsin; only 20% degradation was noted in the former case.

Multilayered mucoadhesive hydrogel films based on thiolated hyaluronic acid and polyvinylalcohol for insulin delivery

A multilayered hydrogel film system based on hyaluronic acid-cysteamine (HA-Cym) and polyvinylalcohol (PVA) was fabricated. It contained a drug-impermeable backing layer, a supporting layer preventing direct contact between the loaded drug and the backing layer, a drug-loading layer and a mucoadhesive layer. Scanning electron microscopy demonstrated the presence of the distinct layers. The composition and preparation procedure of the films influenced their mucoadhesion, swelling, in vitro release of insulin and loaded insulin stability. Vacuum drying and crosslinked PVA with glutaraldehyde might reduce mucoadhesion, and they partially decreased the bioactivity of loaded insulin. Lyophilized hydrogel film with uncrosslinked PVA as a mucoadhesive layer possessed high mucoadhesion and showed no influence on the bioactivity of loaded insulin. The application of vacuum-dried PVA-crosslinked HA-Cym/PVA hydrogel film as a drug-impermeable backing layer would provide a controllable unidirectional insulin release. Therefore, such a multilayered hydrogel film system could be a promising mucoadhesive delivery system for controlled macromolecular drug release.