Mucoadhesive polymeric platforms for controlled drug delivery

Freeze-drying cycle optimization of an amorphous solid dispersion of resveratrol

Resveratrol (RES) has demonstrated advantages as anti-cancer, anti-inflammatory, blood sugar-lowering agent and as cardioprotective agent, among others. Despite RES therapeutic advantages its use in pharmaceutical applications is limited by its low oral bioavailability, mainly due to its poor water solubility. Formulation of poorly water-soluble compound as solid dispersion (SD) converts a crystalline into a more soluble in water amorphous drug. Lyophilization or freeze-drying is a process in which water, an organic solvent, or a co-solvent system is frozen, followed by its removal from the sample, initially by sublimation (primary drying) and then by desorption (secondary drying). This study aimed the development and optimization of a bulk freeze-drying cycle by critical process parameters assessment in each phase to prepare a RES third-generation SD, containing Eudragit E PO as hydrophilic polymer at 1:2 ratio, and Gelucire 44/14 as surfactant at 16 % (w/w) to RES, using a tert-butanol (TBA)/Acetate buffer pH 4.5 (75:25) co-solvent system. A RES third-generation SD with good appearance, not cracked, collapsed, or melted was prepared by an optimized and robust bulk lyophilization process. A physicochemical characterization confirmed the conversion of RES to the amorphous state in the SD and formulation stability after 1 month at 40 °C/75 % RH. Increased solubility and higher dissolution rate compared with pure RES were also obtained.

Association of mucoadhesive polymeric matrices and liposomes for local delivery of miconazole: A new approach for the treatment of oral candidiasis

Since the local treatment of oral candidiasis usually requires long-term administration of the antifungal drug, an ideal dosage form should be able to maintain the drug release over an extended period, assuring an adequate concentration at the infection site. In this context, we have considered the possibility of a buccal delivery of miconazole nitrate (MN) by mucoadhesive polymeric matrices. The loading of the antifungal drug in a hydrophilic matrix was made possible by taking advantage of the amphiphilic nature of liposomes (LP). The MN-loaded LP were prepared by a thin film evaporation method followed by extrusion, while solid matrices were obtained by freeze-drying a suspension of the LP in a polymeric solution based on chitosan (CH), sodium hyaluronate (HYA), or hydroxypropyl methylcellulose (HPMC). MN-loaded LP measured 284.7 ± 20.1 nm with homogeneous size distribution, adequate drug encapsulation efficiency (86.0 ± 3.3 %) and positive zeta potential (+47.4 ± 3.3). CH and HYA-based formulations almost completely inhibited C. albicans growth after 24 h, even if the HYA-based one released a higher amount of the drug. The CH-based matrix also provided the best mucoadhesive capacity and therefore represents the most promising candidate for the local treatment of oral candidiasis.

Specific delivery of metronidazole using microparticles and thermosensitive in situ hydrogel for intrapocket administration as an alternative in periodontitis treatment

Periodontitis is a common chronic inflammatory disease primarily caused by the prevalence of bacterial overgrowth resulting in the development of an inflammatory condition that destroys the tooth's supporting tissues and eventual tooth loss. Comparatively, to other treatment methods, it is difficult for topical antibacterial drugs to effectively permeate the biofilm's physical barrier, making conventional therapy for periodontitis more challenging. This novel study combines thermosensitive in situ hydrogel with microparticles (MPs) to enhance the targeted delivery of metronidazole (MET) to the periodontal pocket. Polycaprolactone (PCL) polymer was utilized to produce bacteria-sensitive MPs. Additionally, the study assessed the attributes of MPs and demonstrated an enhancement in the in vitro antibacterial efficacy of MPs towards Staphylococcus aureus (SA) and Escherichia coli (EC). Subsequently, we incorporated MET-MPs into thermosensitive in situ hydrogel formulations using chitosan. The optimized formulations exhibited stability, appropriate gelation temperature, mucoadhesive strength, and viscosity. In vitro permeation tests showed selective and prolonged drug release against SA and EC. Ex vivo experiments demonstrated no significant differences between in situ hydrogel containing pure MET and MET-MPs in biofilm quantity, bacterial counts, and metabolic activity in biofilms. According to in vitro tests and the effectiveness of the antibacterial activity, this study has exhibited a novel methodology for more efficacious therapies for periodontitis. This study aims to utilize MET in MPs to improve its effectiveness, enhance its antibacterial activity, and improve patient treatment outcomes. In further research, the efficacy of the treatment should be investigated in vivo using an appropriate animal model.

Development of thermosensitive liposome-containing in-situ gel systems for intranasal administration of thiocolchicoside and in vivo evaluation in a rabbit model

AIM

Thiocolchicoside (THC) is a drug under the category of BCS III. Due to its high molecular weight, it has poor oral bioavailability and low skin permeability. This study aims to find an alternative delivery method for THC that enhances its bioavailability through nasal application approach. In situ gels containing plain or liposomal THC with different combinations of Pluronic® F127 and PEG 400 were prepared.

METHOD

Liposome formulations were prepared using the thin film hydration method and tested for their characterization such as for drug content, particle size, and zeta potential. In vivo pharmacokinetic parameters of formulations such as Cmax, Tmax, and AUC were tested on the rabbit model. The formulations were also scrutinized for their cell viability properties.

RESULT

Formulation composition with 2% soybean phosphatidylcholine and 10 mg THC exhibited ∼94% entrapment efficiency, minimum particle size 101.32 nm, low polydispersity index 0.225 and +0.355 zeta potential. In situ liposomal dispersion containing 15% Pluronic® F127 turned into gel at nasal temperature. Cell lines were unharmed for 48 h. İn situ liposomal gels showed 1.5x higher blood concentration than the control formula.

CONCLUSION

In situ gels of liposomal THC formulations offer advantages over traditional nasal solutions, demonstrating comparable bioavailability to parenteral medication while also preserving the health of nasal mucosa cells.

The dawning era of oral thin films for nutraceutical delivery: From laboratory to clinic

Oral thin films (OTFs) are innovative dosage forms that have gained tremendous attention for the delivery of nutraceuticals. They are ultra-thin, flexible sheets that can be easily placed on the tongue, sublingual or buccal mucosa (inner lining of the cheek). These thin films possess several advantages for nutraceutical delivery including ease of administration, rapid disintegration, fast absorption, rapid onset of action, bypass first-pass hepatic metabolism, accurate dosing, enhanced stability, portability, discreetness, dose flexibility and most importantly consumer acceptance. This review highlights the utilization OTFs for nutraceutical delivery, their composition, criteria for excipient selection, methods of development and quality-based design (QbD) approach to achieve quality product. We have also provided recent case studies representing OTFs as promising platform in delivery of nutraceuticals (plant extracts, bioactive molecules, vitamins, minerals and protein/peptides) and probiotics. Finally, we provided advancement in technologies, recent patents, market analysis, challenges and future perspectives associated with this unique dosage form.

A comprehensive review on recent progress in chitosan composite gels for biomedical uses

Chitosan (CS) composite gels have emerged as promising materials with diverse applications in biomedicine. This review provides a concise overview of recent advancements and key aspects in the development of CS composite gels. The unique properties of CS, such as biocompatibility, biodegradability, and antimicrobial activity, make it an attractive candidate for gel-based composites. Incorporating various additives, such as nanoparticles, polymers, and bioactive compounds, enhances the mechanical, thermal, and biological and other functional properties of CS gels. This review discusses the fabrication methods employed for CS composite gels, including blending and crosslinking, highlighting their influence on the final properties of the gels. Furthermore, the uses of CS composite gels in tissue engineering, wound healing, drug delivery, and 3D printing highlight their potential to overcome a number of the present issues with drug delivery. The biocompatibility, antimicrobial properties, electroactive, thermosensitive and pH responsive behavior and controlled release capabilities of these gels make them particularly suitable for biomedical applications. In conclusion, CS composite gels represent a versatile class of materials with significant potential for a wide range of applications. Further research and development efforts are necessary to optimize their properties and expand their utility in pharmaceutical and biomedical fields.

Analysis of Key Factors for Evaluating Mucosal Adhesion Using Swine Buccal Tissue

The assessment of the mucoadhesive properties peak mucoadhesive force (Fmax) and work of mucoadhesion (Wmuc) with texture analyzers is a common in vitro method for analyzing formulation capabilities. Challenges arise in selecting and standardizing experimental conditions due to various variables influencing mucoadhesion. This complexity hampers direct product performance comparisons. In our study, we explored factors (contact force and time, probe speed and mucin in artificial saliva) impacting a model formulation's mucoadhesive capacity. Using Omcilon-A®Orabase on porcine buccal mucosa, we systematically varied experimental conditions, employing a statistical approach (Central Composite Design - CCD). Three variables (contact force, contact time, probe speed) and their interactions were assessed for their impact on Fmax and Wmuc. Results showed that contact time and force positively affected Fmax, while only contact time influenced Wmuc. In the mucin artificial saliva test, a force of 0.5 N, time of 600 s, and speed of 1 mm/s yielded optimal Fmax (0.587 N) and Wmuc (0.468 N.s). These conditions serve as a reference for comparing mucoadhesive properties of formulations for topical oral use.

Novel Drug Delivery Approaches for the Localized Treatment of Cervical Cancer

Cervical cancer (CC) is the fourth leading cancer type in females globally. Being an ailment of the birth canal, primitive treatment strategies, including surgery, radiation, or laser therapy, bring along the risk of infertility, neonate mortality, premature parturition, etc. Systemic chemotherapy led to systemic toxicity. Therefore, delivering a smaller cargo of therapeutics to the local site is more beneficial in terms of efficacy as well as safety. Due to the regeneration of cervicovaginal mucus, conventional dosage forms come with the limitations of leaking, the requirement of repeated administration, and compromised vaginal retention. Therefore, these days novel strategies are being investigated with the ability to combat the limitations of conventional formulations. Novel carriers can be engineered to manipulate bioadhesive properties and sustained release patterns can be obtained thus leading to the maintenance of actives at therapeutic level locally for a longer period. Other than the purpose of CC treatment, these delivery systems also have been designed as postoperative care where a certain dose of antitumor agent will be maintained in the cervix postsurgical removal of the tumor. Herein, the most explored localized delivery systems for the treatment of CC, namely, nanofibers, nanoparticles, in situ gel, liposome, and hydrogel, have been discussed in detail. These carriers have exceptional properties that have been further modified with the aid of a wide range of polymers in order to serve the required purpose of therapeutic effect, safety, and stability. Further, the safety of these delivery systems toward vital organs has also been discussed.

A Window for Enhanced Oral Delivery of Therapeutics via Lipid Nanoparticles

Oral administration of dosage forms is convenient and beneficial in several respects. Lipid nanoparticulate dosage forms have emerged as a useful carrier system in deploying low solubility drugs systemically, particularly class II, III, and IV drugs of the Biopharmaceutics Classification System. Like other nanoparticulate delivery systems, their low size-to-volume ratio facilitates uptake by phagocytosis. Lipid nanoparticles also provide scope for high drug loading and extended-release capability, ensuring diminished systemic side effects and improved pharmacokinetics. However, rapid gastrointestinal (GI) clearance of particulate delivery systems impedes efficient uptake across the mucosa. Mucoadhesion of dosage forms to the GI mucosa results in longer transit times due to interactions between the former and mucus. Delayed transit times facilitate transfer of the dosage form across the mucosa. In this regard, a balance between mucoadhesion and mucopenetration guarantees optimal systemic transfer. Furthermore, the interplay between GI anatomy and physiology is key to ensuring efficient systemic uptake. This review captures salient anatomical and physiological features of the GI tract and how these can be exploited for maximal systemic delivery of lipid nanoparticles. Materials used to impart mucoadhesion and examples of successful mucoadhesive lipid nanoformulations are highlighted in this review.

Mucoadhesive Polymeric Polyologels Designed for the Treatment of Periodontal and Related Diseases of the Oral Cavity

The study objective was to design and characterise herein unreported polyologels composed of a range of diol and triol solvents and polyvinyl methyl ether-co-maleic acid (PVM/MA) and, determine their potential suitability for the treatment of periodontal and related diseases in the oral cavity using suitable in vitro methodologies. Polyologel flow and viscoelastic properties were controlled by the choice of solvent and the concentration of polymer. At equivalent polymer concentrations, polyologels prepared with glycerol (a triol) exhibited the greatest elasticity and resistance to deformation. Within the diol solvents (PEG 400, pentane 1,5-diol, propane 1,2-diol, propane 1,3-diol, and ethylene glycol), PEG 400 polyologels possessed the greatest elasticity and resistance to deformation, suggesting the importance of distance of separation between the diol groups. Using Raman spectroscopy bond formation between the polymer carbonyl group and the diol hydroxyl groups was observed. Polyologel mucoadhesion was influenced by viscoelasticity; maximum mucoadhesion was shown by glycerol polyologels at the highest polymer concentration (20% w/w). Similarly, the choice of solvent and concentration of PVM/MA affected the release of tetracycline from the polyologels. The controlled release of tetracycline for at least 10 h was observed for several polyologels, which, in combination with their excellent mucoadhesion and flow properties, offer possibilities for the clinical use of these systems to treat diseases within the oral cavity.

Valorisation of prawn/shrimp shell waste through the production of biologically active components for functional food purposes

BACKGROUND

The aim of the work was to develop a technology for using waste from prawn and shrimp processing as a source of active ingredients that could be used in the promotion of healthy foods. From fresh and freeze-dried prawn and shrimp shells, protein hydrolysates (carotenoproteins) were obtained using two different enzymes, Flavourzyme and Protamex.

RESULTS

The obtained hydrolysates were characterised in terms of protein content, degree of hydrolysis, and antioxidant and antimicrobial activity. The hydrolysate with the best antioxidant properties (FRAP value of 2933.33 μmol L-1 TE; ORAC value of 115.58 μmol L-1 TE) was selected and tested for its possible use as a component of functional foods. Molecular weight distribution, amino acid profile and free amino acids, the solubility of the hydrolysate in different pH ranges as well as foaming ability were determined. It was found that this hydrolysate was characterised by an amino acid profile with high nutritional value, flavour enhancement properties and excellent solubility in a wide pH range (from 97.06% to 100%). Afterward, the possibility of using carotenoproteins from prawn waste as a component of an emulsion with furcellaran and a lipid preparation of astaxanthin, taken from post-hydrolysate production waste, was investigated. The obtained complexes were stable as proved by the measurement of zeta potential (ζ = -23.87 and -22.32 to -27.79 mV).

CONCLUSION

It is possible to produce stable complexes of the hydrolysate with furcellaran and to emulsify a lipid preparation of astaxanthin, obtained from waste following production of the hydrolysate, in them. © 2023 Society of Chemical Industry.

Ion-activated In Situ Gel of Gellan Gum Containing Chrysin for Nasal Administration in Parkinson's Disease

INTRODUCTION

This study focused on creating an innovative treatment approach for Parkinson's disease (PD), a progressive neurodegenerative condition characterized by the loss of specific neurons in the brain.

AIM

The research aimed to develop a nasal gel using gellan gum containing a complex of chrysin with hydroxypropyl-β-cyclodextrin (HP-β-CD) to enhance the drug's solubility and stability.

METHOD

The formulation process involved utilizing central composite design (CCD) to optimize the concentrations of gellan gum and HPMC E5, with viscosity and mucoadhesive strength as key factors. The resulting optimized In Situ gel comprised 0.7% w/v gellan gum and 0.6% w/v HPMC E5, exhibiting desirable viscosity levels for both sol and gel states, along with robust mucoadhesive properties. The formulated gel underwent comprehensive evaluation, including assessments for gelation, drug content, in vitro drug release, ex vivo permeation, and histopathology.

RESULT

The findings demonstrated superior drug release from the In Situ gel compared to standalone chrysin. Ex vivo studies revealed effective drug permeation through nasal mucosa without causing harm. Moreover, experiments on neuronal cells exposed to oxidative stress (H2O2- induced) showcased significant neuroprotection conferred by chrysin and its formulations. These treatments exhibited notable enhancements in cell viability and reduced instances of apoptosis and necrosis, compared to the control group. The formulations exhibited neuroprotective properties by mitigating oxidative damage through mechanisms, like free radical scavenging and restoration of antioxidant enzyme activity.

CONCLUSION

In conclusion, this developed In situ gel formulation presents a promising novel nasal delivery system for PD therapy. By addressing challenges related to drug properties and administration route, it holds the potential to enhance treatment outcomes and improve the quality of life for individuals with Parkinson's disease.

Biophysical analysis on molecular interactions between chitosan-coated sinapic acid loaded liposomes and mucin

BACKGROUND

The mucus biomembrane is a primary barrier in delivering drugs to the brain via intranasal delivery. The negatively charged nanoformulations suffer from poor mucoadhesive ability and less retention time in the nasal cavity, which limits further therapeutic efficacy. The positively charged chitosan coating on liposomes may overcome the above issues. Hence, understanding the molecular interactions between the chitosan-coated liposomes and mucin is essential for developing an effective drug delivery system.

METHODS

The molecular interactions of mucin with sinapic acid-loaded liposomes (SA-LPs) and mucin with chitosan-coated sinapic acid-loaded liposomes (SA-CH-LPs) were assessed using different biophysical instrumental analyses by interpreting the UV-Vis spectra and observing the particle size, polydispersity index, surface charge, and rheological behavior.

RESULTS

The mucin interaction with SA-CH-LPs showed increased viscosity as compared to SA-LPs with mucin. Moreover, the mucin interaction with SA-CH-LPs showed stronger mucoadhesive properties as compared to SA-LPs with mucin. The electrostatic interaction between positively charged SA-CH-LPs and negatively charged mucin was responsible for the enhanced mucoadhesive property.

CONCLUSION

The positively charged SA-CH-LPs highly interact with mucin as compared to negatively charged SA-LPs. The mucoadhesive property of SA-CH-LPs could improve the retention of SA in the nasal cavity as compared to SA-LPs. These findings emphasize the importance of chitosan in modulating the mucoadhesive behavior of liposomes.

GENERAL SIGNIFICANCE

Overall, this study helps to understand the molecular interactions and mucoadhesive nature of the chitosan-coated liposomes with mucin, which is essential for biological activity in the physiological environment.

Current Drug Delivery Strategies for Buccal Cavity Ailments using Mouth Dissolving Wafer Technology: A Comprehensive Review on the Present State of the Art

BACKGROUND

Mouth-dissolving wafer is polymer-based matrice that incorporates various pharmaceutical agents for oral drug delivery. This polymeric wafer is ingenious in the way that it needs not be administered with water, like in conventional tablet dosage form. It has better compliance among the pediatric and geriatric groups owing to its ease of administration.

OBJECTIVE

The polymeric wafer dissolves quickly in the oral cavity and is highly effective for a targeted local effect in buccal-specific ailments. It is a safe, effective, and versatile drug delivery carrier for a range of drugs used to treat a plethora of oral cavity-specific ailments that inflict common people, like thrush, canker sores, periodontal disease, benign oral cavity tumors, buccal neoplasm, and malignancies. This review paper focuses thoroughly on the present state of the art in mouth-dissolving wafer technology for buccal drug delivery and targeting. Moreover, we have also addressed present-time limitations associated with wafer technology to aid researchers in future developments in the arena of buccal drug delivery.

CONCLUSION

This dynamic novel formulation has tremendous future implications for designing drug delivery systems to target pernicious ailments and diseases specific to the buccal mucosa. In a nutshell, this review paper aims to summarize the present state of the art in buccal targeted drug delivery.

Nose-to-Brain (N2B) Delivery: An Alternative Route for the Delivery of Biologics in the Management and Treatment of Central Nervous System Disorders

In recent years, there have been a growing number of small and large molecules that could be used to treat diseases of the central nervous system (CNS). Nose-to-brain delivery can be a potential option for the direct transport of molecules from the nasal cavity to different brain areas. This review aims to provide a compilation of current approaches regarding drug delivery to the CNS via the nose, with a focus on biologics. The review also includes a discussion on the key benefits of nasal delivery as a promising alternative route for drug administration and the involved pathways or mechanisms. This article reviews how the application of various auxiliary agents, such as permeation enhancers, mucolytics, in situ gelling/mucoadhesive agents, enzyme inhibitors, and polymeric and lipid-based systems, can promote the delivery of large molecules in the CNS. The article also includes a discussion on the current state of intranasal formulation development and summarizes the biologics currently in clinical trials. It was noted that significant progress has been made in this field, and these are currently being applied to successfully transport large molecules to the CNS via the nose. However, a deep mechanistic understanding of this route, along with the intimate knowledge of various excipients and their interactions with the drug and nasal physiology, is still necessary to bring us one step closer to developing effective formulations for nasal-brain drug delivery.

Intestinal retentive systems - recent advances and emerging approaches

Intestinal retentive devices (IRDs) are devices designed to anchor within the lumen of the intestines for long-term residence in the gastrointestinal tract. IRDs can enable impactful medical device technologies including sustained oral drug delivery systems, indwelling sensors, or real-time diagnostics. The design and testing of IRDs present a myriad of challenges, including precise deployment of the device at desired intestinal locations, secure anchoring within the gastrointestinal tract to allow for natural function, and safe removal of the IRD at user-defined times. Advancing the state-of-the-art of IRD is an interdisciplinary effort that requires innovations such as new materials, novel anchoring mechanisms, and medical device design with consistent input from clinical practitioners and end-users. This perspective briefly reviews the current state-of-the-art for IRDs and charts a path forward to inform the design of future concepts. Specifically, this article will highlight materials, retention mechanisms, and test beds to measure the efficacy of IRDs and their mechanisms. Finally, potential synergies between IRD and other medical device technologies are presented to identify future opportunities.

Saltiness perception in gel-based food systems (gels and emulsion-filled gels)

Reducing salt in food without compromising its quality is a huge challenge. Some review articles have been recently published on saltiness perception in some colloidal systems such as emulsions. However, no published reviews are available on saltiness perceptions of gel-based matrices, even though salt release and perception in these systems have been extensively studied. This article reviews the recent advances in salt perception in gel-based systems and provides a detailed analysis of the main factors affecting salt release. Strategies to enhance saltiness perception in gels and emulsion-filled gels are also reviewed. Saltiness perception can be improved through addition of biopolymers (proteins and polysaccharides) due to their ability to modulate texture and/or to adhere to or penetrate through the mucosal membrane on the tongue to prolong sodium retention. The composition of the product and the distribution of salt within the matrix are the two main factors affecting the perception of salty taste. Food structure re-design can lead to control the level of interaction between the salt and other components and change the structure, which in turn affects the mobility and release of the salt. The change of ingredients/matrix can affect the texture of the product, highlighting the importance of sensory evaluation.

The Potential of Films as Transmucosal Drug Delivery Systems

Pharmaceutical films are polymeric formulations used as a delivery platform for administration of small and macromolecular drugs for local or systemic action. They can be produced by using synthetic, semi-synthetic, or natural polymers through solvent casting, electrospinning, hot-melt extrusion, and 3D printing methods, and depending on the components and the manufacturing methods used, the films allow the modulation of drug release. Moreover, they have advantages that have drawn interest in the development and evaluation of film application on the buccal, nasal, vaginal, and ocular mucosa. This review aims to provide an overview of and critically discuss the use of films as transmucosal drug delivery systems. For this, aspects such as the composition of these formulations, the theories of mucoadhesion, and the methods of production were deeply considered, and an analysis of the main transmucosal pathways for which there are examples of developed films was conducted. All of this allowed us to point out the most relevant characteristics and opportunities that deserve to be taken into account in the use of films as transmucosal drug delivery systems.

Adhesive ginsenoside compound K patches for cartilage tissue regeneration

Biomaterial-based drug delivery systems have been developed to expedite cartilage regeneration; however, challenges related to drug recovery, validation, and efficient drug delivery remain. For instance, compound K (CK) is a major metabolite of ginsenosides that is known to protect against joint degeneration by inhibiting the production of inflammatory cytokines and the activation of immune cells. However, its effects on cartilage degradation and tissue regeneration remain unclear. Additionally, tissue-adhesive drug delivery depots that stably adhere to cartilage defects are required for CK delivery. In this study, CK-loaded adhesive patches were reported to seal cartilage defects and deliver CK to defect sites, preventing cartilage degradation and accelerating cartilage tissue regeneration. Adhesive patches are stable and suitable for application in surgical procedures under physiological conditions and show excellent adhesiveness to cartilage surfaces. In addition, there were no significant differences in the adhesive polymeric networks before and after CK loading. CK-loaded hydrocaffeic acid-conjugated chitosan patches significantly inhibited the stimulation of cartilage-degrading enzymes and apoptosis in osteoarthritic cartilage by releasing CK in cartilage defects. Additionally, the NFkB signaling pathway of released CK from the adhesive patches in the treatment of osteoarthritis is revealed. Thus, the CK-loaded adhesive patches are expected to significantly contribute to cartilage regeneration.

Enhancing Antifungal Treatment of Candida albicans with Hypericin-Loaded Nanostructured Lipid Carriers in Hydrogels: Characterization, In Vitro, and In Vivo Photodynamic Evaluation

BACKGROUND

Vulvovaginal candidiasis (VVC) is a worldwide public health problem caused predominantly by the opportunistic polymorphic fungus Candida albicans, whose pathogenicity is associated with its morphological adaptability. To potentiate the treatment of C. albicans-induced VVC by an alternative method as photodynamic therapy (PDT), hypericin (Hy), a potent photosensitizer compound was incorporated into a nanostructured lipid carrier (NLC) and dispersed in hydrogel (HG).

METHODS

After preparation of the sonication process, an NLC loaded with Hy was dispersed in HG based on Poloxamer 407 and chitosan obtaining Hy.NLC-HG. This hydrogel system was physically and chemically characterized and its in vitro and in vivo photodynamic and antifungal effects were evaluated.

RESULTS

Through scanning electron microscopy, it was possible to observe a hydrogel system with a porous polymeric matrix and irregular microcavities. The Hy.NLC-HG system showed mucoadhesive properties (0.45 ± 0.08 N) and a satisfactory injectability (15.74 ± 4.75 N.mm), which indicates that it can be easily applied in the vaginal canal, in addition to a controlled and sustained Hy release profile from the NLC-HG of 28.55 ± 0.15% after 720 min. The in vitro antibiofilm assay significantly reduced the viability of C. albicans (p < 0.001) by 1.2 log10 for Hy.NLC-HG/PDT and 1.9 log10 for PS/PDT, Hy.NLC/PDT, and free RB/PDT, compared to the PBS/PDT negative control. The in vivo antifungal evaluation showed that animals treated with the vaginal cream (non-PDT) and the PDT-mediated Hy.NLC-HG system showed a significant difference of p < 0.001 in the number of C. albicans colonies (log) in the vaginal canal, compared to the inoculation control group.

CONCLUSIONS

Thus, we demonstrate the pharmaceutical, antifungal, and photodynamic potential of hydrogel systems for Hy vaginal administration.

Berberine-phospholipid nanoaggregate-embedded thiolated chitosan hydrogel for aphthous stomatitis treatment

Aim: This study aimed to develop nanoaggregates of berberine-phospholipid complex incorporated into thiolated chitosan (TCS) hydrogel for the treatment of aphthous stomatitis. Methods: The berberine-phospholipid complex was formulated through the solvent evaporation technique and assembled into nanoaggregates. TCS was synthesized through the attachment of thioglycolic acid to chitosan (CS). Nanoaggregates-TCS was prepared by the incorporation of nanoaggregates into TCS and underwent in vitro and in vivo tests. Results: Nanoaggregates-TCS exhibited prolonged release of berberine. The mucoadhesive strength of nanoaggregates-TCS increased 1.75-fold compared with CS hydrogel. In vivo studies revealed the superior therapeutic efficacy of nanoaggregates-TCS compared with that of other groups. Conclusion: Due to prolonged drug release, appropriate residence time and anti-inflammatory effects, nanoaggregates-TCS is an effective system for the treatment of aphthous stomatitis.

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.

Chitosan-based buccal mucoadhesive patches to enhance the systemic bioavailability of tizanidine

Tizanidine hydrochloride (TZN) is a muscle relaxant used to treat a variety of disorders such as painful muscle spasms and chronic spasticity. TZN has low oral bioavailability due to extensive first-pass metabolism and is used orally at a dose of 6-24 mg per day. In the present study, buccal patches were prepared by solvent casting method using chitosan glutamate (Chi-Glu) and novel chitosan azelate (Chi-Aze) which was synthesised in-house for the first time, to enhance the bioavailability of TZN by bypassing first-pass metabolism. The characterisation, mucoadhesion and drug release studies were performed. Chi-Aze patches retained their integrity longer in the buccal medium and showed higher ex vivo drug permeability compared to that prepared with Chi-Glu. In vivo studies revealed that buccal formulation fabricated with Chi-Aze (3%) showed approx 3 times more bioavailability than the orally administered commercial product. Results of the studies indicate that Chi-Aze, prepared by conjugation of chitosan and a fatty acid, the patch formulation is a promising buccal mucoadhesive system due to the physical stability in buccal medium, the good mucoadhesiveness and the high TZN bioavailability. Moreover, Chi-Aze patch might be an alternative to oral formulations of TZN to reduce the dose and frequency of drug administration.

Targeted hollow pollen silica nanoparticles for enhanced intravesical therapy of bladder cancer

Bladder cancer (BC), such as non-muscle invasive bladder cancer (NMIBC), has a significantly high recurrence rate even after intravesical therapy because traditional intravesical chemotherapeutic drugs have short retention time in the bladder and lack efficient uptake in BC cells. Pollen structure usually shows potent adhesion ability to tissue surfaces, different from traditional electronic interaction or covalent binding. 4-Carboxyphenylboric acid (CPBA) has high affinity to sialic acid residues that are overexpressed on BC cells. In the present study, hollow pollen silica (HPS) nanoparticles (NPs) were prepared and modified with CPBA to form CHPS NPs, which could be further loaded with pirarubicin (THP) to form THP@CHPS NPs. THP@CHPS NPs showed high adhesion to skin tissues and could be more efficiently internalized by a mouse bladder cancer cell line (MB49) than THP, inducing more significant apoptotic cells. After intravesical instillation into a BC mouse model through an indwelling catheter, THP@CHPS NPs could more significantly accumulate at the bladder than THP at 24 h post-instillation, and after 8 days of intravesical treatments, magnetic resonance imaging (MRI) revealed that the bladders treated with THP@CHPS NPs showed more smooth bladder lining and more reduction in size and weights than those with THP. Moreover, THP@CHPS NPs exhibited excellent biocompatibility. THP@CHPS NPs hold great potential for intravesical treatment of bladder cancer.

Intranasal in situ gelling liquid crystal for delivery of resveratrol ameliorates memory and neuroinflammation in Alzheimer's disease

Alzheimer's disease (AD) is an illness that affects people aged 65 or older and affects around 6.5 million in the United States. Resveratrol is a chemical obtained from natural products and it exhibits biological activity based on inhibiting the formation, depolymerization of the amyloid, and decreasing neuroinflammation. Due to the insolubility of this compound; its incorporation in surfactant-based systems was proposed to design an intranasal formulation. A range of systems has been produced by mixing oleic acid, CETETH-20 and water. Polarised light microscopy (PLM), small angle x-ray scattering (SAXS) and transmission electron microscopy (TEM) confirm the initial liquid formulation (F) presented as microemulsion (ME). After dilution, the gelled systems were characterized as hexagonal mesophase and they showed feasibility proprieties. Pharmacological assays performed after intranasal administration showed the ability to improve learning and memory in animals, as well as remission of neuroinflammation via inhibition of interleukin.

Hydrogels for Mucosal Drug Delivery

Mucosal tissues are often a desirable site of drug action to treat disease and engage the immune system. However, systemically administered drugs suffer from limited bioavailability in mucosal tissues where technologies to enable direct, local delivery to these sites would prove useful. In this Spotlight on Applications article, we discuss hydrogels as an attractive means for local delivery of therapeutics to address a range of conditions affecting the eye, nose, oral cavity, gastrointestinal, urinary bladder, and vaginal tracts. Considering the barriers to effective mucosal delivery, we provide an overview of the key parameters in the use of hydrogels for these applications. Finally, we highlight recent work demonstrating their use for inflammatory and infectious diseases affecting these tissues.

Cell penetrating peptides-functionalized Licochalcone-A-loaded PLGA nanoparticles for ocular inflammatory diseases: evaluation of in vitro anti-proliferative effects, stabilization by freeze-drying and characterization of an in-situ forming gel

Licochalcone-A (Lico-A) PLGA NPs functionalized with cell penetrating peptides B6 and Tet-1 are proposed for the treatment of ocular anti-inflammatory diseases. In this work, we report the in vitro biocompatibility of cell penetrating peptides-functionalized Lico-A-loaded PLGA NPs in Caco-2 cell lines revealing a non-cytotoxic profile, and their anti-inflammatory activity against RAW 264.7 cell lines. Given the risk of hydrolysis of the liquid suspensions, freeze-drying was carried out testing different cryoprotectants (e.g., disaccharides, alcohols, and oligosaccharide-derived sugar alcohol) to prevent particle aggregation and mitigate physical stress. As the purpose is the topical eye instillation of the nanoparticles, to reduce precorneal wash-out, increase residence time and thus Lico-A bioavailability, an in-situ forming gel based on poloxamer 407 containing Lico-A loaded PLGA nanoparticles functionalized with B6 and Tet-1 for ocular administration has been developed. Developed formulations remain in a flowing semi-liquid state under non-physiological conditions and transformed into a semi-solid state under ocular temperature conditions (35 °C), which is beneficial for ocular administration. The pH, viscosity, texture parameters and gelation temperature results met the requirements for ophthalmic formulations. The gel has characteristics of viscoelasticity, suitable mechanical and mucoadhesive performance which facilitate its uniform distribution over the conjunctiva surface. In conclusion, we anticipate the potential clinical significance of our developed product provided that a synergistic effect is achieved by combining the high anti-inflammatory activity of Lico-A delivered by PLGA NPs with B6 and Tet-1 for site-specific targeting in the eye, using an in-situ forming gel.

Cationic liposomes as promising vehicles for timolol/brimonidine combination ocular delivery in glaucoma: formulation development and in vitro/in vivo evaluation

Glaucoma is a chronic eye disease in which the pressure inside the eye increases and leads to damage to the optic nerve, and eventually causes blindness. In this disease, it is often necessary to use a multi-drug treatment system. There is a fixed combination of timolol maleate and brimonidine tartrate among the combination drugs in glaucoma treatment. Liposomes are one of the most important targeted drug delivery systems to eye tissue, which leads to improved drug permeability and durability in ocular tissue. In this study, thin layer hydration was used to make liposomal formulations containing timolol maleate (TM) and brimonidine tartrate (BT). After the necessary evaluations, one of the eight initial formulations was selected as an optimization formulation. Then, characteristics such as drug loading percentage, particle size, pH, zeta potential, and drug release were performed on the optimized formulation. The study of reducing intraocular pressure was performed on the optimized formulation. This study in total was performed on 18 rabbits in three groups. Hydroxypropyl methylcellulose (HPMC) polymer was injected into the anterior chamber to experimental induce glaucoma. The selected formulation was within the acceptable range of ocular products in terms of physical properties. HPMC polymer injection successfully induced glaucoma in the animal model, resulting in a 79% increase in intraocular pressure. The results showed that the liposomal formulation significantly reduced the intraocular pressure compared to the simple formulation of the aqueous solution, and both formulations were able to significantly reduce the intraocular pressure compared to the control group (P < 0.001). The results also showed that liposomal formulation has a therapeutic effect in reducing intraocular pressure. It seems that the selected liposomal formulation made by thin layer hydration can act as a suitable drug carrier to increase the effectiveness of the fixed combination of timolol maleate and brimonidine tartrate and be proposed as a new drug formulation for targeted and controlled drug delivery in the treatment of glaucoma.

Thermoresponsive mucoadhesive hybrid gels in advanced drug delivery systems

Thermoresponsive polymers have seen extensive use in the development of stimuli-responsive drug formulations for oral, buccal, nasal, ocular, topical, rectal, parenteral, and vaginal routes of administration. Despite their great potential, their use has been limited by various obstacles, such as undesirable high polymer concentration, wide gelation temperature, low gel strength, poor mucoadhesiveness, and short retention. Mucoadhesive polymers have been suggested to improve the mucoadhesive features of thermoresponsive gels, leading to increased drug bioavailability and efficacy. This article highlights the use of in-situ thermoresponsive mucoadhesive hydrogel blends or hybrids that have been developed and assessed in various routes of administration.

In Vitro and In Vivo Evaluation of Carbopol 71G NF-Based Mucoadhesive Minitablets as a Gastroretentive Dosage Form

Gastroretentive dosage forms are intended to stay inside the stomach for a long period of time while releasing an active pharmaceutical ingredient. Such systems may offer significant benefits for numerous drugs compared to other sustained release systems, such as improved pharmacokinetics/bioavailability and reduced intake frequency and thereby improved adherence to the medical therapy. However, there is no gastroretentive product on the market with proven reliable gastroretentive properties in humans. A major obstacle is the motility pattern of the stomach in the fasting state in humans, which reliably ensures gastric emptying of even large indigestible objects into the small intestine. One promising approach to avoid gastric emptying is adhesion of the drug delivery system to the gastric mucosa. In order to achieve mucoadhesive properties, minitablets containing Carbopol 71G NF were developed and compared to minitablets without adhesive properties. In a specialized mucoadhesive test system, the adhesion time was prolonged for adhesive minitablets (240 min) compared to non-adhesive minitablets (30 min). The in vivo transit behavior was investigated using magnetic resonance imaging in 11 healthy volunteers in fasted state in a crossover setup. It was found that the gastric residence time (GRT) of the adhesive minitablets (median of 37.5 min with IQR = 22.5-52.5) was statistically significantly prolonged compared to the non-adhesive minitablets (median of 7.5 with IQR = 7.5-22.5), indicating a delay in gastric emptying by adhesion to the gastric mucosa. However, the system needs further improvement to create a clinical benefit. Furthermore, it was observed that for 9 of 22 administrations (three minitablets were given simultaneously with every administration), the minitablets were not emptied together but showed different GRTs.

Performance and biocompatibility of a novel inhalable dry powder formulation based on hyaluronic acid intended to protect the respiratory tract mucosa

Hyaluronic acid (HA) is a key component of the respiratory mucosa. By acting as a natural moisturizer, it provides hydration to the airways. In normal conditions, high molecular weight HA molecules form viscous gels providing a protective shield against external insults. This is particularly important in the upper airways where the HA protective barrier helps to prevent environmental agents to reach the lungs. Most respiratory diseases are characterized by inflammatory processes causing degradation of HA into small fragments which reduces the HA barrier effect and increases the risk of exposure to external insults. Dry powder inhalers (DPIs) are efficient devices used to deliver therapeutic molecules in the form of dry powder to the respiratory tract. PolmonYDEFENCE/DYFESA™ is a novel formulation based on HA delivered to the airways using the PillHaler® DPI device. In this study we report the results of in vitro inhalation performances of PolmonYDEFENCE/DYFESA™ as well as its mechanism of action in human cells. We found that the product targets the upper airways and that HA molecules form a protective barrier on cell surface. Furthermore, exposure to the device is safe in animal models. The promising pre-clinical results of this study provide the bases for future clinical investigation.

Mucoadhesive drug delivery systems: a promising noninvasive approach to bioavailability enhancement. Part II: formulation considerations

INTRODUCTION

Mucoadhesive drug delivery systems (MDDS) are specifically designed to interact and bind to the mucosal layer of the epithelium for localized, prolonged, and/or targeted drug delivery. Over the past 4 decades, several dosage forms have been developed for localized as well as systemic drug delivery at different anatomical sites.

AREAS COVERED

The objective of this review is to provide a detailed understanding of the different aspects of MDDS. Part II describes the origin and evolution of MDDS, followed by a discussion of the properties of mucoadhesive polymers. Finally, a synopsis of the different commercial aspects of MDDS, recent advances in the development of MDDS for biologics and COVID-19 as well as future perspectives are provided.

EXPERT OPINION

A review of the past reports and recent advances reveal MDDS as highly versatile, biocompatible, and noninvasive drug delivery systems. The rise in the number of approved biologics, the introduction of newer highly efficient thiomers, as well as the recent advances in the field of nanotechnology have led to several excellent applications of MDDS, which are predicted to grow significantly in the future.

Mucoadhesive drug delivery systems: a promising non-invasive approach to bioavailability enhancement. Part I: biophysical considerations

INTRODUCTION

Mucoadhesive drug delivery systems (MDDS) are specifically designed to interact and bind to the mucosal layer for localized, prolonged, and/or targeted drug delivery. Over the past 4 decades, different sites have been explored for mucoadhesion including the nasal, oral, and vaginal cavities, the gastrointestinal tract and ocular tissues.

AREAS COVERED

The present review aims to provide a comprehensive understanding of different aspects of MDDS development. Part I focuses on the anatomical and biological aspects of mucoadhesion, which include a detailed elucidation of the structure and anatomy of the mucosa, the properties of mucin, the different theories of mucoadhesion and evaluation techniques.

EXPERT OPINION

The mucosal layer presents a unique opportunity for effective localization as well as systemic drug delivery via MDDS. Formulation of MDDS requires a thorough understanding of the anatomy of mucus tissue, the rate of mucus secretion and turnover, and the physicochemical properties of mucus. Further, the moisture content and the hydration of polymers are crucial for interaction with mucus. A confluence of different theories used to explain the mechanism of mucoadhesion is useful for understanding the mucoadhesion of different MDDS and their evaluation is subject to factors, such as the site of administration, type of dosage form, and duration of action. [Figure: see text].

Design as strategy for evaluation of the mechanical properties of binary mixtures composed of poly(methyl vinyl ether-alt-maleic anhydride) and Pluronic F127 for biomedical applications

The synergism between thermoresponsive and bioadhesive polymers can lead to the optimization of materials with enhanced mechanical and bioadhesive properties. Quality by Design can assure the understanding and control of formulation variables. In this approach, Design of Experiment has been widely utilized as an important strategy. Poly(methyl vinyl ether-alt-maleic anhydride) (PVMMA) is a bioadhesive polymer and Pluronic F127 (PF127) shows thermoresponsiveness. The association of these two polymers has been poorly investigated. The aim of this work was to study the mechanical, bioadhesive and rheological properties of polymer mixtures composed of PVMMA and PF127, in order to select the best conditions and formulations for biomedical applications. Textural properties (hardness, compressibility, adhesiveness, cohesiveness and elasticity), softness index, bioadhesion and rheological characteristics (flow and viscoelasticity) showed that 17.5-20% (w/w) PF127-polymer mixtures displayed improved values of the parameters. However, the rheological interaction parameter showed low synergism, due to the polymers' characteristics and system organization. The formulations displayed gelation temperatures suitable for administration, with improved bioadhesive properties mainly at 34 °C and suggests the formulations can be used for biomedical applications. DoE constituted an important tool to investigate these systems showing the main effects that significantly influence the binary mixtures.

Surface Modification of Silica Particles with Adhesive Functional Groups or Their Coating with Chitosan to Improve the Retention of Toothpastes in the Mouth

Silica is widely used in the oral care formulations to act as an abrasive and to give the products its distinct physical properties. In this study, silica particles were synthesized using a co-condensation of tetraethyl orthosilicate with a series of functional silane compounds [(3-mercaptopropyl)trimethoxysilane, (3-glycidyloxypropyl)trimethoxysilane, and (3-acryloxypropyl)trimethoxysilane)]. The surface of the particles based on tetraethyl orthosilicate and (3-glycidyloxypropyl)trimethoxysilane was then further modified with 3-aminophenylboronic acid. Commercial Aerosil R972 Pharma silica particles were also coated with chitosan. Additionally, commercially available (3-maleimido)propyl-functionalized silica particles were used in this study. All these functionalized silica particles were incorporated into toothpaste formulations, and their retentive properties were tested on ex vivo sheep tongue mucosa models using fluorescent microscopy-based flow-through techniques. Those surfaces with chitosan, phenylboronic acid, and acryloyl groups were shown to provide a significant improvement in the retention of the oral care formulations during the retention testing. The retention of toothpastes containing silica functionalized with maleimide and thiol groups was also superior compared to that of unmodified silica particles. This study synthesized and tested a range of silica particles and demonstrated that the functionalized silica incorporated into toothpastes can significantly improve the retention of these formulations on oral mucosal surfaces.

Mucoadhesive chitosan-methylcellulose oral patches for the treatment of local mouth bacterial infections

Mucoadhesive buccal patches are dosage forms promising for successful drug delivery. They show the distinctive advantages of long residence time on the oral mucosa and increased in situ drug bioavailability. In this context, electrophoretic deposition (EPD) of chitosan (CS) has been demonstrated as a simple and easily tunable technique to produce mucoadhesive buccal patches. However, CS-based buccal patches may suffer from weak mucoadhesion, which can impair their therapeutic effect. In this work, methylcellulose (MC), a widely investigated biopolymer in the biomedical area, was exploited to increase the mucoadhesive characteristic of pristine CS patches. CS-MC patches were obtained in a one-pot process via EPD, and the possibility of incorporating gentamicin sulfate (GS) as a model of a broad-spectrum antibiotic in the so-obtained patches was investigated. The resulting CS-MC patches showed high stability in a water environment and superior mucoadhesive characteristic (σ_adh = 0.85 ± 0.26 kPa, W_adh = 1192.28 ± 602.36 Pa mm) when compared with the CS control samples (σ_adh = 0.42 ± 0.22 kPa, W_adh = 343.13 ± 268.89 Pa mm), due to both the control of the patch porosity and the bioadhesive nature of MC. Furthermore, GS-loaded patches showed no in vitro cytotoxic effects by challenging L929 cells with material extracts and noteworthy antibacterial activity on both Gram-positive and Gram-negative bacterial strains.

Formulation and In Vitro Evaluation of Mucoadhesive Sustained Release Gels of Phytoestrogen Diarylheptanoids from Curcuma comosa for Vaginal Delivery

Diarylheptanoids (DAs) characterized by a 1,7-diphenylheptane structural skeleton are considered a novel class of phytoestrogens. The DAs available in Curcuma comosa Roxb. (C. comosa) extract demonstrated significant estrogenic activities both in vitro and in vivo. This study aimed to develop and comprehensively evaluate a mucoadhesive vaginal gel for the sustained release of DAs. Different mucoadhesive polymers as gelling agents were investigated. C. comosa ethanolic crude extract was used as a source of DAs. All C. comosa gels were light brown homogeneous with pH within 4.4-4.6. Their flow behaviors were pseudoplastic with a flow behavior index of 0.18-0.38. The viscosity at a low shear rate varied from 6.2 to 335.4 Pa·s. Their mechanical and extrudability properties were associated well with rheological properties. Polycarbophil (PCP):hydroxypropyl methylcellulose (HPMC) blends had a higher mucoadhesiveness to porcine vaginal mucosa than those of PCP-based or HPMC-based gels. All C. comosa gels exhibited a sustained, zero-order DA release pattern over 72 h. Korsmeyer and Peppas equation fitting indicated a non-Fickian, case II transport release mechanism. C. comosa gels had good physical and chemical stability under low-temperature storage for up to 12 months. PCP:HPMC-based mucoadhesive gels could be a proper delivery system for vaginal administration of DAs.

Betaine-modified hydroxyethyl cellulose (HEC): A biodegradable mucoadhesive polysaccharide exhibiting quaternary ammonium substructures

The aim of this study was to improve the mucoadhesive properties of hydroxyethyl cellulose (HEC) via the covalent attachment of betaine. Synthesis was carried out through esterification of HEC utilizing N-chlorobetainyl chloride. Betaine-modified HEC was characterized via FTIR and NMR analyses, ester quantification and zeta potential measurements. Enzymatic degradation and cell viability were also investigated. Moreover, rheological and mucoadhesive properties were evaluated. FTIR and NMR analyses confirmed the covalent attachment of betaine to HEC. Betaine-modified HEC contained 228.45±11.63 µmol/g ester bonds and its zeta potential was 0.37±0.19 mV. Enzymatic degradation studies showed the ability of lipase to cleave off betaine from HEC. Cytotoxicity studies demonstrated that betaine-modified HEC is up to a concentration of 0.3% not toxic. In comparison to unmodified HEC, betaine-modified HEC showed with mucus a 2.3- and 4-fold higher viscosity within 3 h and 6 h, respectively. Furthermore, betaine-modified HEC exhibited 23.5-fold higher mucoadhesive properties on porcine intestinal mucosa compared to unmodified HEC. In conclusion, betaine-modified HEC might be a useful biodegradable mucoadhesive polymer.

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.

A novel nanotechnological mucoadhesive and fast-dissolving film for vaginal delivery of clotrimazole: design, characterization, and in vitro antifungal action

Pullulan (PUL) films containing pomegranate seed oil and Eudragit^® RS100 nanocapsules loaded with clotrimazole (CTZ-NC-PUL) were developed to treat vulvovaginal candidiasis (VVC). Our findings showed that the nanocapsule average diameter was around 163 ± 4 nm, with polydispersity index values of up to 0.1 ± 0.01 and positively charged zeta potential (+ 43.5 ± 0.7 mV). The pH was in the acid range (5.14 ± 0.12) and encapsulation efficiency was around 99.6%; CTZ nanoencapsulation promoted higher homogeneity values for the film (91%), and the stability studies displayed no changes in the drug content after 120 days for the CTZ-NC-PUL under refrigerated conditions. All formulations were considered non-irritant, and CTZ-NC-PUL promoted a controlled release of the drug (60% in 24 h) compared to CTZ-PUL (100% in 8 h). The permeation results corroborate the drug release, where higher CTZ amounts were found in the mucosa and receptor medium for CTZ-PUL (21.02 and 4.46 μg/cm²). The films were fast dissolving (10 min), and CTZ-NC-PUL presented higher mucoadhesive properties; the antifungal activity against Candida albicans was maintained, and the in vitro efficacy of the film was proved. In conclusion, CTZ-NC-PUL formulation was considered promising and suitable for vaginal application against candida-related infections.

Photo-Phytotherapeutic Gel Composed of Copaifera reticulata, Chlorophylls, and k-Carrageenan: A New Perspective for Topical Healing

Chronic wound healing represents an impactful financial burden on healthcare systems. In this context, the use of natural products as an alternative therapy reduces costs and maintains effectiveness. Phytotherapeutic gels applied in photodynamic therapy (PDT) have been developed to act as topical healing medicines and antibiotics. The bioactive system is composed of Spirulina sp. (source of chlorophylls) and Copaifera reticulata oil microdroplets, both incorporated into a polymeric blend constituted by kappa-carrageenan (k-car) and F127 copolymer, constituting a system in which all components are bioactive agents. The flow behavior and viscoelasticity of the formulations were investigated. The photodynamic activity was accessed from studies of the inactivation of Staphylococcus aureus bacteria, the main pathogen of hospital relevance. Furthermore, in vivo studies were conducted using eighteen rabbits with dermatitis (grade III and IV) in both paws. The gels showed significant antibiotic potential in vitro, eliminating up to 100% of S. aureus colonies in the presence or absence of light. The k-car reduced 41% of the viable cells; however, its benefits were enhanced by adding chlorophyll and copaiba oil. The animals treated with the phytotherapeutic medicine showed a reduction in lesion size, with healing and re-epithelialization verified in the histological analyses. The animals submitted to PDT displayed noticeable improvement, indicating this therapy's viability for ulcerative and infected wounds. This behavior was not observed in the iodine control treatment, which worsened the animals' condition. Therefore, gel formulations were a viable alternative for future pharmaceutical applications, aiming at topical healing.

Hydroxyethylcellulose-Based Hydrogels Containing Liposomes Functionalized with Cell-Penetrating Peptides for Nasal Delivery of Insulin in the Treatment of Diabetes

Liposomes functionalized with cell-penetrating peptides are a promising strategy to deliver insulin through the nasal route. A hydrogel based on hydroxyethylcellulose (HEC) aqueous solution was prepared, followed by a subsequent addition of liposomes containing insulin solution functionalized with trans-activator of transcription protein of HIV-1 (TAT) or Penetratin (PNT). The formulations were characterized for rheological behavior, mucoadhesion, syringeability, in vitro release and in vivo efficacy. Rheological tests revealed non-Newtonian fluids with pseudoplastic behavior, and the incorporation of liposomes (HLI, HLI_TAT and HLI_PNT) in hydrogels did not alter the behavior original pseudoplastic characteristic of the HEC hydrogel. Pseudoplastic flow behavior is a desirable property for formulations intended for the administration of drugs via the nasal route. The results of syringeability and mucoadhesive strength from HEC hydrogels suggest a viable vehicle for nasal delivery. Comparing the insulin release profile, it is observed that HI was the system that released the greatest amount while the liposomal gel promoted greater drug retention, since the liposomal system provides an extra barrier for the release through the hydrogel. Additionally, it is observed that both peptides tested had an impact on the insulin release profile, promoting a slower release, due to complexation with insulin. The in vitro release kinetics of insulin from all formulations followed Weibull's mathematical model, reaching approximately 90% of release in the formulation prepared with HEC-based hydrogels. Serum insulin levels and the antihyperglycemic effects suggested that formulations HI and HLI have potential as carriers for insulin delivery by the nasal pathway, a profile not observed when insulin was administered by subcutaneous injection or by the nasal route in saline. Furthermore, formulations functionalized with TAT and PNT can be considered promoters of late and early absorption, respectively.

Mucoadhesive carriers for oral drug delivery

Among the various dosage forms, oral medicine has extensive benefits including ease of administration and patients' compliance, over injectable, suppositories, ocular and nasal. Despite of extensive demand and emerging advantages, over 50% of therapeutic molecules are not available in oral form due to their physicochemical properties. More importantly, most of the biologics, proteins, peptide, and large molecular drugs are mostly available in injectable form. Conventional oral drug delivery system has limitation such as degradation and lack of stability within stomach due to presence of highly acidic gastric fluid, hinders their therapeutic efficacy and demand more frequent and higher dosing. Hence, formulation for controlled, sustained, and targeted drug delivery, need to be designed with feasibility to target the specific region of gastrointestinal (GI) tract such as stomach, small intestine, intestine lymphatic, and colon is challenging. Among various oral delivery approaches, mucoadhesive vehicles are promising and has potential for improving oral drug retention and controlled absorption to treat local diseases within the GI tract, as well systemic diseases. This review provides the overview about the challenges and opportunities to design mucoadhesive formulation for oral delivery of therapeutics in a way to target the specific region of the GI tract. Finally, we have concluded with future perspective and potential of mucoadhesive formulations for oral local and systemic delivery.

Self-Emulsifying Drug Delivery System Enhances Tissue Distribution of Cinnamaldehyde by Altering the Properties of the Mucus Layer

Oral delivery is considered the preferred route of administration due to its convenience and favorable compliance. However, this delivery often faces difficulties, such as poor solubility, limited absorption, and undesirable stability, especially for some volatile oils. The aim of this study was to develop self-emulsifying drug delivery systems (SEDDS) containing cinnamaldehyde (CA) to overcome these shortcomings. The CA-SEDDS were spherical and smooth with an average size of 14.96 ± 0.18 nm. Differential scanning calorimetry (DSC) and attenuated total reflection by Fourier transform infrared (ATR-FTIR) showed that CA has been successfully loaded into SEDDS. The accumulative release of CA-SEDDS (73.39%) was approximately 2.14-fold that of free CA when using simulated intestinal fluid as the release medium. A scanning electron microscope was used to observe the mucus network structure. Rheological tests found that CA-SEDDS can appropriately enhance the viscosity of the mucus system. We found from tissue distribution studies that CA was more widely distributed in various tissues in the CA-SEDDS group compared to the free CA group. The cinnamaldehyde and cinnamon acid also accumulated more in various tissues in the CA-SEDDS group than in the free CA group, especially in the kidney. These findings hinted that SEDDS exhibited lower irritation, good release, and penetration, which demonstrated great potential for utilizing CA. Our research supports the rational implications of SEDDS in delivering similar volatile substances by improving the solubility, mucus penetration, and stability, resulting in excellent clinical efficacy.

Mucoadhesive Marine Polysaccharides

Mucoadhesive polymers are of growing interest in the field of drug delivery due to their ability to interact with the body’s mucosa and increase the effectiveness of the drug. Excellent mucoadhesive performance is typically observed for polymers possessing charged groups or non-ionic functional groups capable of forming hydrogen bonds and electrostatic interactions with mucosal surfaces. Among mucoadhesive polymers, marine carbohydrate biopolymers have been attracting attention due to their biocompatibility and biodegradability, sample functional groups, strong water absorption and favorable physiochemical properties. Despite the large number of works devoted to mucoadhesive polymers, there are very few systematic studies on the influence of structural features of marine polysaccharides on mucoadhesive interactions. The purpose of this review is to characterize the mucoadhesive properties of marine carbohydrates with a focus on chitosan, carrageenan, alginate and their use in designing drug delivery systems. A wide variety of methods which have been used to characterize mucoadhesive properties of marine polysaccharides are presented in this review. Mucoadhesive drug delivery systems based on such polysaccharides are characterized by simplicity and ease of use in the form of tablets, gels and films through oral, buccal, transbuccal and local routes of administration.

Development of early diagnosis of Parkinson's disease on animal models based on the intranasal administration of α-methyl-p-tyrosine methyl ester in a gel system

The fight against neurodegenerative diseases, including Parkinson's disease (PD), is a global challenge of this century. The effectiveness of current PD therapy is limited, since it is diagnosed many years after the onset, following the death of most nigrostriatal dopaminergic neurons regulating motor function. PD treatment could be greatly improved if it was started at an early (preclinical) stage. For this purpose, it is necessary to develop an early diagnosis of PD, which is the goal of our study. We have developed an early diagnosis of PD on animal models using a provocative test by intranasal administration of α-methyl-p-tyrosine methyl ester (αMPTME), a reversible inhibitor of dopamine synthesis. First, we produced the provocative agent, αMPTME in gel, and showed its safety and penetration into the brain bypassing the blood-brain barrier. Then, the optimal dose of αMPTME and time after administration were selected, at which the level of dopamine in the striatum of intact animals decreases, but does not reach the 30% threshold for the appearance of motor disorders in PD patients. Finally, we proved on animal models that intranasal administration of αMPTME can serve as a diagnostic test for preclinical PD. Indeed, intranasal administration of αMPTME to mice in a model of PD at the preclinical stage reversibly reduced the dopamine level in the striatum to the 30% threshold causing short-term motor disorders. Thus, using animal models of PD, we have developed a provocative test for the preclinical diagnosis of PD, a fundamentally new technology in neurology.