Development and characterization of mucoadhesive-thermoresponsive gels for the treatment of oral mucosa diseases

Novel Thermosensitive and Mucoadhesive Nasal Hydrogel Containing 5-MeO-DMT Optimized Using Box-Behnken Experimental Design

We present the development and characterization of a nasal drug delivery system comprised of a thermosensitive mucoadhesive hydrogel based on a mixture of the polymers Poloxamer 407, Poloxamer 188 and Hydroxypropyl-methylcellulose, and the psychedelic drug 5-methoxy-N,-N-dimethyltryptamine. The development relied on a 3 × 3 Box-Behnken experimental design, focusing on optimizing gelification temperature, viscosity and mucoadhesion. The primary objective of this work was to tailor the formulation for efficient nasal drug delivery. This would increase contact time between the hydrogel and the mucosa while preserving normal ciliary functioning. Following optimization, the final formulation underwent characterization through an examination of the in vitro drug release profile via dialysis under sink conditions. Additionally, homogeneity of its composition was assessed using Raman Confocal Spectroscopy. The results demonstrate complete mixing of drug and polymers within the hydrogel matrix. Furthermore, the formulation exhibits sustained release profile, with 73.76% of the drug being delivered after 5 h in vitro. This will enable future studies to assess the possibility of using this formulation to treat certain mental disorders. We have successfully developed a promising thermosensitive and mucoadhesive hydrogel with a gelling temperature of around 32 °C, a viscosity close to 100 mPas and a mucoadhesion of nearly 4.20 N·m.

In Situ Gelling Behavior and Biopharmaceutical Characterization of Nano-Silver-Loaded Poloxamer Matrices Designed for Nasal Drug Delivery

A combination of Poloxamer 407 (P407) and hydroxypropyl methylcellulose (HPMC) hydrosols is proposed as an in situ thermo-gelling vehicle for the nasal drug delivery of chlorhexidine-silver nanoparticles conjugates (SN-CX). Optimization of the formulation was carried out by applying varying ratios of P407 and HPMC in the presence and absence of SN-CX so that gelation would occur in the temperature range of the nasal cavity (30-34 °C). Mechanisms for the observed gelation phenomena were suggested based on viscosimetry, texture analysis, and dynamic light scattering. Tests were carried out for sprayability, washout time, in vitro drug release, ex vivo permeation, and antimicrobial activity. When applied separately, HPMC was found to lower the P407 gelation temperature (Tg), whereas SN-CX increased it. However, in the presence of HPMC, SN-CX interfered with the P407 micellar organization in a principally contrasting way while leading to an even further decrease in Tg. SN-CX-loaded nasal formulations composed of P407 16% and HPMC 0.1% demonstrated a desired gelation at 31.9 °C, good sprayability (52.95% coverage of the anterior nasal cavity), mucoadhesion for 70 min under simulated nasal clearance, expedient release and permeation, and preserved anti-infective activity against seasonal Influenza virus and beta-coronavirus, Pseudomonas aeruginosa, Klebsiella pneumoniae, Staphylococcus aureus and other pathogens. Our findings suggest that the current development could be considered a potential formulation of a protective nasal spray against respiratory infections.

On the mucoadhesive properties of synthetic and natural polyampholytes

HYPOTHESIS

The mucoadhesive characteristics of amphoteric polymers (also known as polyampholytes) can vary and are influenced by factors such as the solution's pH and its relative position against their isoelectric point (pHIEP). Whilst the literature contains numerous reports on mucoadhesive properties of either cationic or anionic polymers, very little is known about these characteristics for polyampholytes EXPERIMENTS: Here, two amphoteric polymers were synthesized by reaction of linear polyethylene imine (l-PEI) with succinic or phthalic anhydride and their mucoadhesive properties were compared to bovine serum albumin (BSA), selected as a natural polyampholyte. Interactions between these polymers and porcine gastric mucin were studied using turbidimetric titration and isothermal titration calorimetry across a wide range of pHs. Model tablets were designed, coated with these polymers and tested to evaluate their adhesion to porcine gastric mucosa at different pHs. Moreover, a retention study using fluorescein isothiocyanate (FITC)-labelled polyampholytes deposited onto mucosal surfaces was also conducted FINDINGS: All these studies indicated the importance of solution pH and its relative position against pHIEP in the mucoadhesive properties of polyampholytes. Both synthetic and natural polyampholytes exhibited strong interactions with mucin and good mucoadhesive properties at pH < pHIEP.

In-situ gel: A smart carrier for drug delivery

In-situ gel technology is a promising drug delivery strategy that undergoes a 'sol to gel' transition upon administration, providing controlled and prolonged drug release. These gels are composed of cross-linked 3D networks of polymers, with hydrogels being a specific type of absorbing water while retaining their shape. Gelation can be triggered by various stimuli, such as temperature, pH, ions, and light. They offer several advantages like improved patient compliance, extended drug residence time, localized drug delivery, etc, but also have some disadvantages like drug degradation and limited mechanical strength. In-situ gel falls into three categories: temperature-sensitive, ion-sensitive, and pH-sensitive, but multi-responsive gels that respond to multiple stimuli have better drug release characteristics. The mechanism of in-situ gel formation involves physical and chemical mechanisms. There are various applications of in-situ gel, like ocular drug delivery, nose-to-brain delivery, etc. In this review, we have discussed the types, and mechanisms of in-situ gel & use of in-situ gel in the treatment of different diseases through various routes like buccal, vaginal, ocular, nasal, etc., along with its use in targeted drug delivery.

Novel Sprayable Thermosensitive Benzydamine Hydrogels for Topical Application: Development, Characterization, and In Vitro Biological Activities

Benzydamine hydrochloride (BZD) having analgesic, anesthetic, and anti-inflammatory effects is used orally or topically in the treatment of disorders such as joint inflammation and muscle pain. Within the scope of this study, sprayable thermosensitive BZD hydrogels were developed using thermoresponsive poloxamers to avoid systemic side effects and to provide better compliance for topical administration. Also, hydroxypropyl methyl cellulose (HPMC) was employed to improve the mechanical strength and bioadhesive properties of the hydrogel. The addition of BZD generally decreased the viscosity of the formulations (p < 0.05), while increasing the gelation temperature (p < 0.05). The formulations that did not have any clogs or leaks in the nozzle of the bottle during the spraying process were considered lead formulations. To spray the formulations easily, it was found that the viscosity at RT should be less than 200 mPa·s, and their gelation temperature should be between 26 and 34°C. Increasing HPMC and poloxamer improved bioadhesion. The amount of HPMC and poloxamers did not cause a significant change in the release characteristics of the formulations (p > 0.05); the release profiles of BZD from the formulations were similar according to model-independent kinetic (f2 > 50). HPMC and poloxamers had important roles in the accumulation of BZD in the skin. In vitro biological activity studies demonstrated that the formulations presented their anti-inflammatory activity with TNF-α inhibition but did not have any effect on the inhibition of COX enzymes as expected. As a result, thermosensitive hydrogels containing BZD might be an appropriate alternative, providing an advantage in terms of easier application compared to conventional gels.

Development of a Novel Histatin-5 Mucoadhesive Gel for the Treatment of Oral Mucositis: In Vitro Characterization and In Vivo Evaluation

Antimicrobial peptides have appeared to be promising candidates for therapeutic purposes due to their broad antimicrobial activity and non-toxicity. Histatin-5 (Hst-5) is a notable salivary antimicrobial peptide that exhibited therapeutic properties in the oral cavity. Oral mucositis is an acute inflammation of the oral cavity, following cancer therapy. The current treatment methods of oral mucositis have low effectiveness. The aim of this study was to design, formulate and characterize a mucoadhesive gel delivery system for Hst-5 usage in the treatment of oral mucositis. Carbopol 934 and hydroxypropyl methylcellulose (HPMC) have been used in the development of a Hst-5 mucoadhesive gel that was optimized by using Box-Behnken design. The optimized formulation was evaluated in-vitro, based on mucoadhesive strength, viscoelasticity, spreadability, release rate, peptide secondary structure analysis, antimicrobial activity, and storage stability. The efficacy of Hst-5 gel was assessed in vivo in a chemotherapy-induced mucositis model. The results showed a sustained release of Hst-5 from the new formulation. Hst-5 gel exerted antimicrobial activity against Staphylococcus aureus, Pseudomonas aeruginosa, Escherichia coli, and Candida albicans. The histopathological, immunohistochemical and statistical analysis showed that the Hst-5 gel had wound healing activity in vivo. The findings of this study indicate that the mentioned compound possesses promising potential as a novel and efficient therapeutic agent in managing oral mucositis. Moreover, the results suggest that the compound is commercially feasible for further development and utilization.

Boosting the photodynamic activity of erythrosine B by using thermoresponsive and adhesive systems containing cellulose derivatives for topical delivery

Erythrosine displays potential photodynamic activity against microorganisms and unhealthy cells. However, erythrosine has high hydrophilicity, negatively impacting on permeation through biological membranes. Combining biological macromolecules and thermoresponsive polymers may overcome these erythrosine-related issues, enhancing retention of topically applied drugs. The aim of this work was to investigate the performance of adhesive and thermoresponsive micellar polymeric systems, containing erythrosine in neutral (ERI) or disodium salt (ERIs) states. Optimized combinations of poloxamer 407 (polox407) and sodium carboxymethylcellulose (NaCMC) or hydroxypropyl methylcellulose (HPMC) were used as platforms for ERI/ERIs delivery. The rheological and mechanical properties of the systems was explored. Most of the formulations were plastic, thixotropic and viscoelastic at 37 °C, with suitable gelation temperature for in situ gelation. Mechanical parameters were reduced in the presence of the photosensitizer, improving the softness index. Bioadhesion was efficient for all hydrogels, with improved parameters for mucosa in contrast to skin. Formulations composed of 17.5 % polox407 and 3 % HPMC or 1 % NaCMC with 1 % (w/w) ERI/ERIs could release the photosensitizer, reaching different layers of the skin/mucosa, ensuring enough production of cytotoxic species for photodynamic therapy. Functional micelles could boost the photodynamic activity of ERI and ERIs, improving their delivery and contact time with the cells.

Enhancement of in-vitro anti-oral cancer activities of silymarin using dispersion of nanostructured lipid carrier in mucoadhesive in-situ gel

Silymarin (SME) shows multiple therapeutic actions against several cancers, however, low aqueous solubility and poor bioavailability issues restrict its clinical use. In this study, SME was loaded in nanostructured lipid carriers (NLCs) and further incorporated in mucoadhesive in-situ gel (SME-NLCs-Plx/CP-ISG) for localized treatment of oral cancer. Using a 3³ Box-Behnken design (BBD), an optimized SME-NLC formula was developed with the ratios of solid lipids, surfactant concentration, and sonication time as independent variables, while particle size (PS), polydispersity index (PDI), and % encapsulation efficiency (EE) as dependent variables, resulting in 315.5 ± 0.1 nm PS, 0.341 ± 0.01 PDI, and 71.05 ± 0.05 % EE. Structural studies confirmed the formation of SME-NLCs. SME-NLCs incorporated in-situ gel demonstrated a sustained release for SME, indicating enhanced retention on the buccal mucosal membrane. The in-situ gel containing SME-NLCs showed a marked decrease in IC₅₀ value (24.90 ± 0.45 µM) than SME-NLCs (28.40 ± 0.89 µM) and plain SME (36.60 ± 0.26 µM). The studies demonstrated that Reactive oxygen species (ROS) generation potential and SME-NLCs-Plx/CP-ISG induced apoptosis at Sub-G0 phase owing to higher penetration of SME-NLCs led to higher inhibition against human KB oral cancer cells. Therefore, SME-NLCs-Plx/CP-ISG can be the alternative to chemotherapy and surgery with site-specific delivery of SME to oral cancer patients.

Polydopamine/tannic acid/chitosan/poloxamer 407/188 thermosensitive hydrogel for antibacterial and wound healing

The design and development of smart shape-adaptable wound dressings with superior antimicrobial ability remain a challenge in therapeutic and clinical application. Herein, polydopamine/tannic acid/chitosan/poloxamer 407/188 hydrogel (PTCPP) was prepared with the aim of developing an in situ-formed antibacterial wound dressing with temperature stimulation and near-infrared radiation (NIR) responsive ability. PTCPP possessed injectability, photothermal stability, sustained release properties and cytocompatibility. In vitro antibacterial results showed that the bactericidal rates of PTCPP against Staphylococcus aureus (S. aureus) and Escherichia coli (E. coli) under NIR irradiation were 99.994 % and 99.91 %, respectively. In vivo experiments, PTCPP can adapt to shape of the wound, showing good adhesion, while promoting wound healing in bacterial infections. Therefore, PTCPP has potential application in the treatment of infectious wounds, and provides a strategic choice for developing antibacterial wound dressing combined with photothermal therapy.

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.

Microemulsion-thermosensitive gel composites as in situ-forming drug reservoir for periodontitis tissue repair through alveolar bone and collagen regeneration strategy

A satisfactory clinical effect in treating periodontitis is often difficult to achieve by conventional non-surgical systemic drug delivery due to the narrow anatomical structure of the periodontal pocket and insufficient drug concentration at lesion sites. In addition, the feasibility of combating periodontal tissue lesions by restoring the alveolar bone and allowing collagen regeneration has not been fully explored. The objective of this study was to prepare a microemulsion integrating the anti-inflammatory and osteogenic active ingredients of baicalin and clove oil (BC-MEs). Then, the composite hydrogel obtained by mixing poloxamer 407 and 188 was used as the thermosensitive gel matrix to load BC-MEs and form a drug reservoir (Gel-BC-MEs) injectable in situ. Gel-BC-MEs exhibited a significant, sustained release of baicalin for 12 h, gelation temperature was 33.4 ± 0.36 °C, and pH was 5.45 ± 0.12. The experiment on a rat periodontitis model demonstrated that Gel-BC-MEs significantly improved periodontal tissue repair by collagen regeneration and osteogenesis by inhibiting osteoclast infiltration. This study proposes a novel strategy for periodontal tissue repair by enhancing the therapeutic potential of a microemulsion using an in situ nano-gel delivery system.

Nanostructured lipid carrier-loaded metformin hydrochloride: Design, optimization, characterization, assessment of cytotoxicity and ROS evaluation

Metformin hydrochloride (MET) is commonly used in diabetes treatment. Recently, it has gained interest for its anticancer potential against a wide range of cancers. Owing to its hydrophilic nature, the delivery and clinical actions of MET are limited. Therefore, the present work aims to develop MET-encapsulated NLCs using the hot-melt emulsification and probe-sonication method. The optimization was accomplished by 3³ BB design wherein lipid ratio, surfactant concentration, and sonication time were independent variables while the PS (nm), PDI, and EE (%) were dependent variables. The PS, PDI, % EE and ZP of optimized _GMSMET-NLCs were found to be 114.9 ± 1.32 nm, 0.268 ± 0.04 %, 60.10 ± 2.23 %, and ZP - 15.76 mV, respectively. The morphological features, DSC and PXRD, and FTIR analyses suggested the confirmation of formation of the NLCs. Besides, optimized _GMSMET-NLCs showed up to 88 % MET release in 24 h. Moreover, _GMSMET-NLCs showed significant cell cytotoxicity against KB oral cancer cells compared with MET solution as shown by the reduction of IC₅₀ values. Additionally, _GMSMET-NLCs displayed significantly increased intracellular ROS levels suggesting the _GMSMET-NLCs induced cell death in KB cells. _GMSMET-NLCs can therefore be explored to deliver MET through different routes of administration for the effective treatment of oral cancer.

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.

Full-Thickness Oral Mucoperiosteal Defects: Challenges and Opportunities

Regenerative engineering strategies for the oral mucoperiosteum, as may be needed following surgeries, such as cleft palate repair and tumor resection, are underdeveloped compared with those for maxillofacial bone. However, critical-size tissue defects left to heal by secondary intention can lead to complications, such as infection, fistula formation, scarring, and midface hypoplasia. This review describes current clinical practice for replacing mucoperiosteal tissue, including autografts and allografts. Potentially paradigm-shifting experimental regenerative engineering strategies for mucoperiosteal wound healing, such as hybrid grafts and engineered matrices, are also discussed. Throughout the review, the advantages and disadvantages of each replacement or regeneration strategy are outlined in the context of clinical outcomes, quality of life for the patient, availability of materials, and cost of care. Finally, future directions for research and development in the area of mucoperiosteum repair are proposed, with an emphasis on identifying globally available and affordable solutions for promoting mucoperiosteal regeneration. Impact statement Unassisted oral mucoperiosteal wound healing can lead to severe complications such as infection, fistulae, scarring, and developmental abnormalities. Thus, strategies for promoting wound healing must be considered when mucoperiosteal defects are incident to oral surgery, as in palatoplasty or tumor resection. Emerging mucoperiosteal tissue engineering strategies, described in this study, have the potential to overcome the limitations of current standard-of-care donor tissue grafts. For example, the use of engineered mucoperiosteal biomaterials could circumvent concerns about tissue availability and immunogenicity. Moreover, employment of tissue engineering strategies may improve the equity of oral wound care by increasing global affordability and accessibility of materials.

Thermosensitive Hydrogels and Advances in Their Application in Disease Therapy

Thermosensitive hydrogels, having unique sol–gel transition properties, have recently received special research attention. These hydrogels exhibit a phase transition near body temperature. This feature is the key to their applications in human medicine. In addition, hydrogels can quickly gel at the application site with simple temperature stimulation and without additional organic solvents, cross-linking agents, or external equipment, and the loaded drugs can be retained locally to improve the local drug concentration and avoid unexpected toxicity or side effects caused by systemic administration. All of these features have led to thermosensitive hydrogels being some of the most promising and practical drug delivery systems. In this paper, we review thermosensitive hydrogel materials with biomedical application potential, including natural and synthetic materials. We describe their structural characteristics and gelation mechanism and briefly summarize the mechanism of drug release from thermosensitive hydrogels. Our focus in this review was to summarize the application of thermosensitive hydrogels in disease treatment, including the postoperative recurrence of tumors, the delivery of vaccines, the prevention of postoperative adhesions, the treatment of nervous system diseases via nasal brain targeting, wound healing, and osteoarthritis treatment.

Drug delivery systems for oral disease applications

There are many restrictions on topical medications for the oral cavity. Various factors affect the topical application of drugs in the oral cavity, an open and complex environment. The complex physical and chemical environment of the oral cavity, such as saliva and food, will influence the effect of free drugs. Therefore, drug delivery systems have served as supporting structures or as carriers loading active ingredients, such as antimicrobial agents and growth factors (GFs), to promote antibacterial properties, tissue regeneration, and engineering for drug diffusion. These drug delivery systems are considered in the prevention and treatment of dental caries, periodontal disease, periapical disease, the delivery of anesthetic drugs, etc. These carrier materials are designed in different ways for clinical application, including nanoparticles, hydrogels, nanofibers, films, and scaffolds. This review aimed to summarize the advantages and disadvantages of different carrier materials. We discuss synthesis methods and their application scope to provide new perspectives for the development and preparation of more favorable and effective local oral drug delivery systems.

Thermosensitive Chitosan-Containing Hydrogels: Their Formation, Properties, Antibacterial Activity, and Veterinary Usage

Mixtures of aqueous solutions of chitosan hydrochloride (CS·HCl, 1–4 wt.%) and Pluronic F-127 (Pl F-127, 25 wt.%) were studied using vibrational and rotational viscometry; the optimal aminopolysaccharide concentration (3 wt.%) and the CS·HCl:Pl F-127 ratio (30:70) to obtain a thermosensitive hydrogel were found. It was shown that at 4 °C, such mixed compositions were viscous liquids, while at 37 °C for 1–2 min, they undergo a thermally reversible transition to a shape-stable hydrogel with a developed level of structure formation, satisfactory viscosity and high mucoadhesive parameters (maximum pull-off force F_max = 1.5 kN/m²; work of adhesion W = 66.6 × 10⁻³ J). Adding D-ascorbic acid to the hydrogel led to orientational ordering of the supramolecular structure of the mixed system and significantly improved mucoadhesion (F_max = 4.1 kN/m², W = 145.1 × 10⁻³ J). A microbiological study revealed the high antibacterial activity of the hydrogel against Gram-negative and Gram-positive bacterial strains. The treatment of mixed bacterial infection in cows demonstrated the possibility of the in situ formation of a viscoelastic gel and revealed its high therapeutic effect. It has been suggested that our thermosensitive mucoadhesive CS·HCl:Pl F-127 hydrogels could be considered as independent veterinary drugs and pharmaceuticals.

Drug Delivery Platforms Containing Thermoresponsive Polymers and Mucoadhesive Cellulose Derivatives: A Review of Patents

Nowadays, the development of mucoadhesive systems for drug delivery has gained keen interest, with enormous potential in applications through different routes. Mucoadhesion characterizes an attractive interaction between the pharmaceutical dosage form and the mucosal surface. Many polymers have shown the ability to interact with mucus, increasing the residence time of local and/or systemic administered preparations, such as tablets, patches, semi-solids, and micro and nanoparticles. Cellulose is the most abundant polymer on the earth. It is widely used in the pharmaceutical industry as an inert pharmaceutical ingredient, mainly in its covalently modified forms: methylcellulose, ethylcellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methylcellulose, and carboxymethylcellulose salts. Aiming to overcome the drawbacks of oral, ocular, nasal, vaginal, and rectal routes and thereby maintaining patient compliance, innovative polymer blends have gained the interest of the pharmaceutical industry. Combining mucoadhesive and thermoresponsive polymers allows for simultaneous in situ gelation and mucoadhesion, thus enhancing the retention of the system at the site of administration and drug availability. Thermoresponsive polymers have the ability to change physicochemical properties triggered by temperature, which is particularly interesting considering the physiological temperature. The present review provides an analysis of the main characteristics and applications of cellulose derivatives as mucoadhesive polymers and their use in blends together with thermoresponsive polymers, aiming at platforms for drug delivery. Patents were reviewed, categorized, and discussed, focusing on the applications and pharmaceutical dosage forms using this innovative strategy. This review manuscript also provides a detailed introduction to the topic and a perspective on further developments.

Hydrogels for modified-release drug delivery systems

Hydrogels for the modified-release drug delivery systems is a continuously growing area of interest for the pharmaceutical industry. According to the global market, the use of polymers in this area is projected to reach $31.4 million by 2027. This review discusses the recent advances and perspectives of hydrogel in drug delivery systems for oral, parenteral, nasal, topical, and ophthalmic. The search strategy did in January 2021, and it conducted an extensive database to identify studies published from January 2010 to December 2020.We described the main characteristic of the polymers to obtain an ideal hydrogel for a specific route of administration and the formulations that was a highlight in the literature. It concluded that the hydrogels are a set useful to decrease the number of doses, side effects, promote adhesion of patient and enhances the bioavailability of the drugs improving the safety and efficacy of the treatment.

Development of mucoadhesive modified kappa-carrageenan/pectin patches for controlled delivery of drug in the buccal cavity

In this study, modified kappa-carrageenan/pectin hydrogel patches were fabricated for treatment of buccal fungal infections. For this purpose, kappa-carrageenan-g-acrylic acid was modified with different thiolated agents (L-cysteine and 3-mercaptopropionic acid), and the thiol content of the resulting modified kappa-carrageenan was confirmed by elemental analyzer. Then, the hydrogel patches were fabricated, and characterized by Fourier-transform infrared spectroscopy, thermogravimetric analysis, ex vivo mucoadhesion test, and swelling behavior. Triamcinolone acetonide was added either directly or by encapsulating within the poly(lactic-co-glycolic acid) nanoparticles. The release amount of the drug from the directly loaded patch was 7.81 mg/g polymer, while it was 3.28 mg/g polymer for the encapsulated patch with the same content at 7 hr. The hydrogel patches had no cytotoxicity by cell culture studies. Finally, the drug loaded hydrogel patches were demonstrated antifungal activity against Aspergillus fumigatus and Aspergillus flavus. These results provide that the novel modified kappa-carrageenan and pectin based buccal delivery system has promising antifungal property, and could have advantages compared to conventional buccal delivery systems.

The effect of erythrosine-B on the structuration of poloxamer 407 and cellulose derivative blends: In silico modelling supporting experimental studies

Erythrosine is a dye approved for medical use that has shown promising photodynamic activity, allowing for the inactivation of microorganisms and activity against malignant cells. Despite the great photodynamic potential, erythrosine exhibits hydrophilicity, negatively impacting its action in biological membranes. Therefore, the incorporation of erythrosine in micellar polymeric systems, such as poloxamers, may overcome this limitation. Moreover, using bioadhesive and thermoresponsive polymers to combine in situ gelation and bioadhesion may enhance retention of this topically applied drug. In this work, mucoadhesive and thermoresponsive micellar systems were prepared containing erythrosine in two states: the native form (ERI) and the disodium salt (ERIs). The systems were evaluated based on the effect of ERI/ERIs on the micellar structure of the binary polymer mixtures. Optimised combinations of poloxamer 407 (polox407) and mucoadhesive sodium carboxymethylcellulose (NaCMC) or hydroxypropyl methylcellulose (HPMC) were used as micellar systems for ERI or ERIs delivery. The systems were studied with respect to theoretical interactions, qualitative composition, morphology, and micellar properties. In silico modelling indicated a higher interaction of the drug with poly(ethylene oxide) (PEO) than poly(propylene oxide) (PPO) fragments of polox407. Systems containing NaCMC displayed a repulsive effect in the presence of erythrosine, due to the polymer's charge density. Both systems could convert the photosensitizer in its monomeric form, ensuring photodynamic activity. In these mixtures, crystallinity, critical micellar temperature and enthalpy of polox407 micellisation were reduced, and micellar size, evaluated by transmission electron microscopy (TEM), showed low impact of ERI/ERIs in HPMC preparations. Aiming toward photodynamic applications, the findings showed how ERI or ERIs can affect the micellar formation of gels composed of 17.5% (w/w) polox407 and 3% (w/w) HPMC or 1% (w/w) NaCMC, important for understating their behaviour and future utilisation as erythrosine delivery systems.

An Overview on Thermosensitive Oral Gel Based on Poloxamer 407

In this review, we describe the application of thermosensitive hydrogels composed of poloxamer in medicine, especially for oral cavities. Thermosensitive hydrogels remain fluid at room temperature; at body temperature, they become more viscous gels. In this manner, the gelling system can remain localized for considerable durations and control and prolong drug release. The chemical structure of the poloxamer triblock copolymer leads to an amphiphilic aqueous solution and an active surface. Moreover, the poloxamer can gel by forming micelles in an aqueous solution, depending on its critical micelle concentration and critical micelle temperature. Owing to its controlled-release effect, a thermosensitive gel based on poloxamer 407 (P407) is used to deliver drugs with different characteristics. As demonstrated in studies on poloxamer formulations, an increase in gelling viscosity decreases the drug release rate and gel dissolution time to the extent that it prolongs the drug’s duration of action in disease treatment. This property is used for drug delivery and different therapeutic applications. Its unique route of administration, for many oral diseases, is advantageous over traditional routes of administration, such as direct application and systemic treatment. In conclusion, thermosensitive gels based on poloxamers are suitable and have great potential for oral disease treatment.

Interaction between mucoadhesive cellulose derivatives and Pluronic F127: Investigation on the micelle structure and mucoadhesive performance

Systems composed of bioadhesive and thermoresponsive polymers can combine in situ gelation with bio/mucoadhesion, enhancing retention of topically applied drugs. The effect of bioadhesive sodium carboxymethylcellulose (NaCMC) and hydroxypropyl methylcellulose cellulose (HPMC) on the properties of thermoresponsive Pluronic® F127 (F127) was explored, including micellization and the mucoadhesion. A computational analysis between these polymers and their molecular interactions were also studied, rationalising the design of improved binary polymeric systems for pharmaceutical and biomedical applications. The morphological characterization of polymeric systems was conducted by SEM. DSC analysis was used to investigate the crystallization and micellization enthalpy of F127 and the mixed systems. Micelle size measurements and TEM micrographs allowed for investigation into the interference of cellulose derivatives on F127 micellization. Both cellulose derivatives reduced the critical micellar concentration and enthalpy of micellization of F127, altering hydrodynamic diameters of the aggregates. Mucoadhesion performance was useful to select the best systems for mucosal application. The systems composed of 17.5% (w/w) F127 and 3% (w/w) HPMC or 1% (w/w) NaCMC are promising as topical drug delivery systems, mainly on mucosal surfaces. They were biocompatible when tested against Artemia salina, and also able to release a model of hydrophilic drug in a controlled manner.

Recent Advances in the Development of In Situ Gelling Drug Delivery Systems for Non-Parenteral Administration Routes

In situ gelling drug delivery systems have gained enormous attention over the last decade. They are in a sol-state before administration, and they are capable of forming gels in response to different endogenous stimuli, such as temperature increase, pH change and the presence of ions. Such systems can be administered through different routes, to achieve local or systemic drug delivery and can also be successfully used as vehicles for drug-loaded nano- and microparticles. Natural, synthetic and/or semi-synthetic polymers with in situ gelling behavior can be used alone, or in combination, for the preparation of such systems; the association with mucoadhesive polymers is highly desirable in order to further prolong the residence time at the site of action/absorption. In situ gelling systems include also solid polymeric formulations, generally obtained by freeze-drying, which, after contact with biological fluids, undergo a fast hydration with the formation of a gel able to release the drug loaded in a controlled manner. This review provides an overview of the in situ gelling drug delivery systems developed in the last 10 years for non-parenteral administration routes, such as ocular, nasal, buccal, gastrointestinal, vaginal and intravesical ones, with a special focus on formulation composition, polymer gelation mechanism and in vitro release studies.

Development of Morin-Loaded Nanoemulsions Containing Various Polymers; Role of Polymers in Formulation Properties and Bioavailability

Emulsions for oral delivery are not suitable for sustained drug absorption because such preparations diffuse rapidly in the gastrointestinal (GI) tract after oral administration. In order to generate sustained drug absorption and increase oral bioavailability, various polymers were added to a morin (MO) nanoemulsion to improve retention in the GI tract and alter the surface properties of oil droplets in the nanoemulsion. The influence of these polymers on the formulation properties was investigated. The area under the blood concentration-time curve (AUC) and the mean residence time (MRT) after oral administration of the nanoemulsions were measured, and the influence of the polymers on bioavailability was investigated. Chitosan (Chi) addition MO nanoemulsion (MO-Chi nanoemulsion) showed the highest AUC and MRT. MO-Chi nanoemulsion increased retention in the GI tract because of the relatively higher viscosity and high affinity between mucin and Chi covering the oil droplets. Furthermore, MO-Chi nanoemulsion could maintain the drug in oil droplets by suppression of drug release through the polymer hydration layer, and sustained drug release achieved continuous drug absorption. Nanoemulsions with sodium carboxymethylcellulose and poly-γ-glutamic acid potassium salt showed the next highest AUC and MRT after MO-Chi nanoemulsion. From these results, it was suggested that by increasing the viscosity of the nanoemulsion, there was high affinity between the added polymer and mucin, and sustained drug release was useful for enhancing the bioavailability of the polymer-containing nanoemulsions.