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.

The role of Eudragit® as a component of hydrogel formulations for medical devices

Over the last decade, significant progress has been made in developing hydrogels as medical devices. By physically cross-linking pharmaceutically approved polymers into three-dimensional matrices, we can ensure their biocompatibility and facilitate their seamless transition from the laboratory to clinical applications. Moreover, the reversible nature of their physical cross-links allows hydrogels to dissolve in the presence of external stimuli. Particularly, their high degree of hydration, high molecular weight, and superior flexibility of the polymer chains facilitate their interaction with complex biological barriers (e.g., mucus layer), making them ideal candidates for mucosal drug delivery. However, fine-tuning the composition of the hydrogel formulations is of great importance to optimize the performance of the medical device and its therapeutic cargo. Herein, we investigated the influence of different Eudragits® on the properties of hydrogels based on polyvinylpyrrolidone (PVP), polyvinyl alcohol (PVA), and polyethylene glycol (PEG), which were originally proposed as ocular inserts in previous reports. Our research aims to determine the effects that including different Eudragits® have on the structure and protein ocular delivery ability of various hydrogel formulations. Properties such as matrix stability, protein encapsulation, release kinetics, mucoadhesion, and biocompatibility have been analyzed in detail. Our study represents a guideline of the features that Eudragits® have to exhibit to endow hydrogels with good adhesion to the eye's conjunctiva, biocompatibility, and structural strength to cope with the ocular biointerface and allow sustained protein release. This work has important implications for the design of new hydrogel materials containing Eudragits® in their composition, particularly in mucosal drug delivery.

Chitosan/Solid-Lipid Nanoparticles Hybrid Gels for Vaginal Delivery of Estradiol for Management of Vaginal Menopausal Symptoms

Hormonal replacement therapy is the mainstay treatment to improve quality of life and reduce mortality. With the increasing number of young women with early menopause, women now live longer (increased life expectancy). However, poor patient compliance with oral estrogen therapy has emerged. Intravaginal estrogen therapy can provide significant benefits with minimal risk for postmenopausal women with symptoms of the lower urinary tract and vaginal area but who do not want to take oral estrogen. In this study, estradiol-loaded solid lipid nanoparticles (SLPs) were prepared from compritol ATO 888 and precirol ATO 5, and two different stabilizers (Pluronic F127 and Tween 80) were studied. Selected SLPs (F3 and F6) were coated with different concentrations of the mucoadhesive and sustained-release polymer chitosan. Furthermore, gelation time, viscosity, mucoadhesion, ex vivo permeation, and in vitro irritation for vaginal irritation were studied. Particle sizes ranged between 450-850 nm, and EE% recorded 50-83% for the six SLPs depending on the type and amount of lipids used. Cumulative % drug release was significantly enhanced and was recorded at 51% to 83%, compared to that (less than 20%) for the control suspension of estradiol. Furthermore, extensive thermal gelation and mucoadhesion were recorded for chitosan-coated SLPs. Up to 2.2-fold increases in the permeation parameters for SLPs gels compared to the control suspension gel were recorded, revealing a slight to moderate irritation on Hela cell lines. These findings demonstrated chitosan-coated estradiol SLPs as novel and promising vaginal mucoadhesive hybrid nanogels.

Beyond traditional therapy: Mucoadhesive polymers as a new frontier in oral cancer management

In recent times mucoadhesive drug delivery systems are gaining popularity in oral cancer. It is a malignancy with high global prevalence. Despite significant advances in cancer therapeutics, improving the prognosis of late-stage oral cancer remains challenging. Targeted therapy using mucoadhesive polymers can improve oral cancer patients' overall outcome by offering enhanced oral mucosa bioavailability, better drug distribution and tissue targeting, and minimizing systemic side effects. Mucoadhesive polymers can also be delivered via different formulations such as tablets, films, patches, gels, and nanoparticles. These polymers can deliver an array of medicines, making them an adaptable drug delivery approach. Drug delivery techniques based on these mucoadhesive polymers are gaining traction and have immense potential as a prospective treatment for late-stage oral cancer. This review examines leading research in mucoadhesive polymers and discusses their potential applications in treating oral cancer.

Nanotechnology-based mucoadhesive and mucus-penetrating drug-delivery systems for transbuccal drug delivery

Buccal drug-delivery systems present a promising approach for the drug delivery to the buccal mucosa, addressing oral cavity-specific problems, enabling systemic delivery and minimizing adverse effects on biological systems. Numerous strategies have been proposed to load drug-containing nanoparticles (NPs) to the buccal mucosa for local and systemic applications. There has been considerable interest in the development of mucoadhesive buccal formulations, particularly hydrogel composites utilizing mucoadhesive films incorporating NPs. Drug permeability and controlled drug release through buccal drug delivery continues to pose a challenge despite the availability of various remedies. This review highlights the need for, mechanisms and latest advances in NP-based transbuccal drug delivery with a focus on various pathological disorders and examples and limitations of the different methods.

Extraction, Characterization, and Evaluation of Lepidium sativum Linn. Mucilage as a Mucoadhesive Polymer

Being biocompatible, less toxic, cheap, easily available, and environmentally friendly, there is an increased trust in natural polymers in the drug delivery system. Mucilages, among the natural polymers, are the primary metabolites of plants that have been widely utilized in pharmaceutical manufacturing for different purposes, and mucoadhesive is one among them. The present study was designed to investigate the use of LSM as a mucoadhesive polymer using ibuprofen as a model drug. The mucilage was extracted following an aqueous extraction method and its percentage yield was found to be 13.2% w/w. Besides, three microsphere formulations of ibuprofen were prepared using synthetic polymer hydroxyl propyl methyl cellulose (HPMC) K100M and the LSM in polymer to drug ratios of 1 : 1, 1 : 5, and 3 : 5 by applying ionotropic gelation followed by solvent evaporation methods. The microspheres were evaluated for various micromeritic properties and all the formulations exhibited free-flowing properties. Optical microscopic pictures of almost all the microspheres except F3 and F6 (which had more or less spherical shapes) were found to have irregular and discrete shapes. Besides, the surfaces of all the formulations were rough in texture. The drug entrapment efficiency of the microspheres was found to be between 52.08% ± 0.80 and 87.97% ± 0.72. The in-vitrowash-off test evidenced that almost 50 percent (especially F3) of the microspheres were able to adhere up to 18 h and showed remarkable bioadhesion properties. The in-vitro drug release profile indicated that all the formulations were able to prolong their drug release up to 12 h with a non-fickian release mechanism, except for F4, which followed a fickian release. Therefore, based on the findings of this study, LSM can be used as a potential alternative mucoadhesive excipient for sustained release formulations.

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 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.

Voriconazole Eye Drops: Enhanced Solubility and Stability through Ternary Voriconazole/Sulfobutyl Ether β-Cyclodextrin/Polyvinyl Alcohol Complexes

Voriconazole (VCZ) is a broad-spectrum antifungal agent used to treat ocular fungal keratitis. However, VCZ has low aqueous solubility and chemical instability in aqueous solutions. This study aimed to develop VCZ eye drop formulations using cyclodextrin (CD) and water-soluble polymers, forming CD complex aggregates to improve the aqueous solubility and chemical stability of VCZ. The VCZ solubility was greatly enhanced using sulfobutyl ether β-cyclodextrin (SBEβCD). The addition of polyvinyl alcohol (PVA) showed a synergistic effect on VCZ/SBEβCD solubilization and a stabilization effect on the VCZ/SBEβCD complex. The formation of binary VCZ/SBEβCD and ternary VCZ/SBEβCD/PVA complexes was confirmed by spectroscopic techniques and in silico studies. The 0.5% w/v VCZ eye drop formulations were developed consisting of 6% w/v SBEβCD and different types and concentrations of PVA. The VCZ/SBEβCD systems containing high-molecular-weight PVA prepared under freeze-thaw conditions (PVA-H hydrogel) provided high mucoadhesion, sustained release, good ex vivo permeability through the porcine cornea and no sign of irritation. Additionally, PVA-H hydrogel was effective against the filamentous fungi tested. The stability study revealed that our VCZ eye drops provide a shelf-life of more than 2.5 years at room temperature, while a shelf-life of only 3.5 months was observed for the extemporaneous Vfend^® eye drops.

Thiolated pectin-chitosan composites: Potential mucoadhesive drug delivery system with selective cytotoxicity towards colorectal cancer

Mucoadhesive drug delivery systems (DDS) may promote safer chemotherapy for colorectal cancer (CRC) by maximizing local drug distribution and residence time. Carbohydrate polymers, e.g. pectin (P) and chitosan (CS), are potential biomaterials for CRC-targeted DDS due to their gelling ability, mucoadhesive property, colonic digestibility, and anticancer activity. Polymer mucoadhesion is augmentable by thiolation, e.g. pectin to thiolated pectin (TP). Meanwhile, P-CS polyelectrolyte complex has been shown to improve structural stability. Herein, we fabricated, characterized, and evaluated 5-fluorouracil-loaded primary DDS combining TP and CS as a composite (TPCF) through triple crosslinking actions (calcium pectinate, polyelectrolyte complex, disulfide). Combination of these crosslinking yields superior mucoadhesion property relative to single- or dual-crosslinked counterparts, with comparable drug release profile and drug compatibility. PCF and TPCF exhibited targeted cytotoxicity towards HT29 CRC cells with milder cytotoxicity towards HEK293 normal cells. In conclusion, TP-CS composites are promising next-generation mucoadhesive and selectively cytotoxic biomaterials for CRC-targeted DDS.

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.

Formulation and Physical Characterization of a Polysaccharidic Gel for the Vehiculation of an Insoluble Phytoextract for Mucosal Application

Maintaining insoluble plant-based ingredients in suspension and ensuring long-term physical stability is particularly challenging for formulators of green cosmetics. This study aimed to evaluate the structure and applicative properties of gel and gel-cream topical formulations suitable for delivering an insoluble phytocomplex on the vaginal mucosa and maintaining its integrity. For this purpose, we studied the compatibility of Perilla frutescens (L.) Britton phytocomplex (PFP), derived from in vitro plant cell cultures and presented as a powder finely dispersed in glycerin, with different classes of natural rheological modifiers (such as xanthan gum, sclerotium gum, succinoglycan, xyloglucan, diutan gum, hydroxypropyl guar gum derivative) in gel and gel-cream formulations, to meet the needs of the cosmetic market for naturalness and biodegradability. Through rheological and texture analyses, we studied the physico–mechanical properties of the samples, comparing the performances of the chosen polysaccharides to those of acrylic polymeric rheological modifiers, evaluating their contribution in terms of stability and applicative properties. Since a weak-gel rheological pattern proved to be the optimal one to keep the actives in suspension, the associations of tamarind seed polysaccharides with succinoglycan or scleroglucan were the most suitable for the formulation of mucoadhesive gels.

Bacterial cellulose adhesive patches designed for soft mucosal interfaces

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

Tailoring the properties of chitosan by grafting with 2-mercaptobenzoic acid to improve mucoadhesion: in silico studies, synthesis and characterization

Mucoadhesive polymers improve oral bioavailability of drugs by prolonging the duration of adhesion of drugs with mucosa. Various methods could be employed to address the problems of mucoadhesive polymers like weak adhesion forces. Chemical modification of polymers, such as the addition of a thiol group or thiolation, is another way for improving the polymers' mucoadhesive properties that is studied in present research work. A novel thiomer of chitosan was prepared by attaching 2-mercaptobenzoic acid, a hydrophobic ligand onto it. The docking of thiomer and chitosan with mucin structure showed higher binding energy for former. The prepared thiomer was subjected to X-ray diffraction and DSC which established reduction in crystallinity and formation of a new compound through changes in glass transition, melting point and change in diffraction pattern. The NMR studies established conjugation of 2-mercapto benzoic acid to chitosan. The increased mucoadhesion in thiomer behaviour (2-3 fold) was confirmed through mucus glycoprotein assay as well as through texture analysis. The permeation enhancing the property of thiomer was established by demonstrating the permeation of phenol red across thiomer treated intestinal membrane. An in vitro cell toxicity assay was done to establish toxicity of chitosan and thiolated chitosan. Finally, the reduced water uptake of thiomer over chitosan proved that the increase in mucoadhesion is not contributed by swelling. Thus, a thiomer with improved mucoadhesion and enhanced permeation properties was prepared and characterized. Hence, all these properties render the newly synthesized polymer a better alternative to chitosan as an excipient for mucoadhesive drug delivery systems.

Mucoadhesive Polymers and Their Applications in Drug Delivery Systems for the Treatment of Bladder Cancer

Bladder cancer (BC) is the tenth most common type of cancer worldwide, affecting up to four times more men than women. Depending on the stage of the tumor, different therapy protocols are applied. Non-muscle-invasive cancer englobes around 70% of the cases and is usually treated using the transurethral resection of bladder tumor (TURBIT) followed by the instillation of chemotherapy or immunotherapy. However, due to bladder anatomy and physiology, current intravesical therapies present limitations concerning permeation and time of residence. Furthermore, they require several frequent catheter insertions with a reduced interval between doses, which is highly demotivating for the patient. This scenario has encouraged several pieces of research focusing on the development of drug delivery systems (DDS) to improve drug time residence, permeation capacity, and target release. In this review, the current situation of BC is described concerning the disease and available treatments, followed by a report on the main DDS developed in the past few years, focusing on those based on mucoadhesive polymers as a strategy. A brief review of methods to evaluate mucoadhesion properties is also presented; lastly, different polymers suitable for this application are discussed.

Development of Novel S-Protective Thiolated-Based Mucoadhesive Tablets for Repaglinide: Pharmacokinetic Study

Mucoadhesive polymers have an essential role in drug localization and target-specific actions in oral delivery systems. The current work aims to develop and characterize a new mucoadhesive polysaccharide polymer (thiolated xanthan gum-TXG and S-Protected thiolated xanthan gum-STX) that was further utilized for the preparation of repaglinide mucoadhesive tablets. The thiolation of xanthan gum was carried out by ester formation through the reaction of the hydroxyl group of xanthan gum and the carboxyl group of thioglycolic acid. Synthesis of TXG was optimized using central composite design, and TXG prepared using 5.303 moles/L of TGA and 6.075 g/L of xanthan gum can accomplish the prerequisites of the optimized formulation. Consequently, TXG was further combined with aromatic 2-mercapto-nicotinic acid to synthesize STX. TXG and STX were further studied for Fourier-transform infrared spectroscopy, rheological investigations, and Ellman’s assay (to quantify the number of thiol/disulfide groups). A substantial rise in the viscosity of STX might be due to increased interactions of macromolecules liable for improving the mucosal adhesion strength of thiolated gum. STX was proven safe with the support of cytotoxic study data. Mucoadhesive formulations of repaglinide-containing STX showed the highest ex vivo mucoadhesion strength (12.78 g-RSX-1 and 17.57 g- RSX-2) and residence time (>16 h). The improved cross-linkage and cohesive nature of the matrix in the thiolated and S-protected thiolated formulations was responsible for the controlled release of repaglinide over 16 h. The pharmacokinetic study revealed the greater AUC (area under the curve) and long half-life with the RSX-2 formulation, confirming that formulations based on S-protected thiomers can be favorable drug systems for enhancing the bioavailability of low-solubility drugs.

Recent advances in functionally modified polymers for mucoadhesive drug delivery

Novel methods for the delivery of drugs other than the conventional method of oral administration have been a thrust area of research for a few decades. Mucoadhesive delivery of drugs opened up a new domain where rapid and patient-friendly delivery of drugs can be achieved. Delivery of drugs through the mucosal sites such as buccal, nasal, ocular, sublingual, rectal and vaginal facilitates bypassing the first-pass metabolism and the drug reaches the systemic circulation directly. This helps to increase the bioavailability of the drug. The study of the chemical characteristics of polymers with mucoadhesive properties and how the molecules or the pharmaceuticals are transported across the mucosa is very much needed for the advancement of research in this field. And at the same time, it is very pertinent to know about the anatomy and the physiology of the mucosal tissue and its variation in different regions of the body. In this review, we try to present a comprehensive understanding of relevant topics of mucoadhesion giving more emphasis on the mechanism of transport of drugs across mucosa, and different possible functional modifications of polymers to enhance the property of mucoadhesion.

Molecular Mapping of Antifungal Mechanisms Accessing Biomaterials and New Agents to Target Oral Candidiasis

Oral candidiasis has a high rate of development, especially in immunocompromised patients. Immunosuppressive and cytotoxic therapies in hospitalized HIV and cancer patients are known to induce the poor management of adverse reactions, where local and systemic candidiasis become highly resistant to conventional antifungal therapy. The development of oral candidiasis is triggered by several mechanisms that determine oral epithelium imbalances, resulting in poor local defense and a delayed immune system response. As a result, pathogenic fungi colonies disseminate and form resistant biofilms, promoting serious challenges in initiating a proper therapeutic protocol. Hence, this study of the literature aimed to discuss possibilities and new trends through antifungal therapy for buccal drug administration. A large number of studies explored the antifungal activity of new agents or synergic components that may enhance the effect of classic drugs. It was of significant interest to find connections between smart biomaterials and their activity, to find molecular responses and mechanisms that can conquer the multidrug resistance of fungi strains, and to transpose them into a molecular map. Overall, attention is focused on the nanocolloids domain, nanoparticles, nanocomposite synthesis, and the design of polymeric platforms to satisfy sustained antifungal activity and high biocompatibility with the oral mucosa.

Advances in the Prophylaxis of Respiratory Infections by the Nasal and the Oromucosal Route: Relevance to the Fight with the SARS-CoV-2 Pandemic

In this time of COVID-19 pandemic, the strategies for prevention of the infection are a primary concern. Looking more globally on the subject and acknowledging the high degree of misuse of protective face masks from the population, we focused this review on alternative pharmaceutical developments eligible for self-defense against respiratory infections. In particular, the attention herein is directed to the nasal and oromucosal formulations intended to boost the local immunity, neutralize or mechanically "trap" the pathogens at the site of entry (nose or mouth). The current work presents a critical review of the contemporary methods of immune- and chemoprophylaxis and their suitability and applicability in topical mucosal dosage forms for SARS-CoV-2 prophylaxis.

Bioadhesive Nanoparticles for Local Drug Delivery

Local drug delivery is an effective strategy for achieving direct and instant therapeutic effects. Current clinical treatments have fallen short and are limited by traditional technologies. Bioadhesive nanoparticles (NPs), however, may be a promising carrier for optimized local drug delivery, offering prolonged drug retention time and steadily maintained therapeutic concentrations. In addition, the possibility of clinical applications of this platform are abundant, as most polymers used for bioadhesion are both biodegradable and biocompatible. This review highlights the major advances in the investigations of polymer-based bioadhesive nanoparticles and their innumerable applications in local drug delivery.

Sodium Alginate as a Pharmaceutical Excipient: Novel Applications of a Well-known Polymer

Alginates are naturally occurring polymers revealing low toxicity, good biocompatibility and biodegradability, excellent gelling and thickening properties, as well as low production cost and good availability. One of the most important features typical for alginates is the ability to undergo ionotropic gelation which is gel formation process occurring upon the contact with cations. Because of their advantageous properties, alginates have been extensively utilized in food and pharmaceutical industries. In this review the current knowledge regarding the most recent studies involving both popularly applied dosage forms, like tablets or hydrogels, and novel advanced drug delivery systems applied in targeted therapies are summarized and discussed. The presented studies indicate that although sodium alginate is a well-established polymer, it is still widely applied as pharmaceutical excipient and the presented research studies indicate that there are still research areas that can be explored and provide innovation in drug delivery systems.

Emerging Biopolymer-Based Bioadhesives

Bioadhesives have been widely used in healthcare and biomedical applications due to their ease-of-operation for wound closure and repair compared to conventional suturing and stapling. However, several challenges remain for developing ideal bioadhesives, such as unsatisfied mechanical properties, non-tunable biodegradability, and limited biological functions. Considering these concerns, naturally derived biopolymers have been considered good candidates for making bioadhesives owing to their ready availability, facile modification, tunable mechanical properties, and desired biocompatibility and biodegradability. Over the past several years, remarkable progress has been made on biopolymer-based adhesives, covering topics from novel materials designs and advanced processing to clinical translation. The developed bioadhesives have been applied for diverse applications, including tissue adhesion, hemostasis, antimicrobial, wound repair/tissue regeneration, and skin-interfaced bioelectronics. Here in this comprehensive review, recent progress on biopolymer-based bioadhesives is summarized with focuses on clinical translations and multifunctional bioadhesives. Furthermore, challenges and opportunities such as weak adhesion strength at the hydrated state, mechanical mismatch with tissues, and unfavorable immune responses are discussed with an aim to facilitate the future development of high-performance biopolymer-based bioadhesives.

Bigels as drug delivery systems: From their components to their applications

Bigels are systems that usually result from mixing a hydrogel and an organogel: the aqueous phase is commonly formed by a hydrophilic biopolymer, whereas the organic phase comprises a gelled vegetable oil because of the presence of an organogelator. The proportion of the corresponding gelling agent in each phase, the organogel/hydrogel ratio, and the mixing temperature and speed all need to be taken into consideration for bigel manufacturing. Bigels, which are particularly useful drug delivery systems, have already been formulated for transdermal, buccal, and vaginal routes. Mechanical assessments and microscopy are the most reported characterization techniques. As we review here, their composition and unique structure confer promising drug delivery attributes, such as mucoadhesion, the ability to control drug release, and the possibility of including both hydrophilic and lipophilic drugs in the same system.

Combination of transdermal patches and solid microneedles for improved transdermal delivery of primaquine

Malaria caused by various types of Plasmodium has become a global health problem. One of the drugs used as the first line of malaria therapy is primaquine (PMQ). PMQ is generally administered through the oral route. However, the use of PMQ orally could potentially cause some side effects and undergo the first-pass metabolism in the liver, reducing its effectiveness. Therefore, it is necessary to develop another drug administration route to avoid this effect. In this study, for the first time, PMQ was formulated into a transdermal patch for transdermal delivery, combined with solid microneedles, Dermaroller®. Following several optimizations, HPMC and glycerin were used as the main polymer and plasticizer, respectively. Specifically, the concentration of PEG 400 as a permeation enhancer was also optimized. The transdermal patches were evaluated for weight uniformity, thickness, surface pH, folding endurance, moisture content, moisture absorption ability, bioadhesive evaluation, and drug content recovery. PMQ release and permeation were also investigated through in vitro and ex vivo tests on rats' skin tissue. Importantly, the safety of the transdermal patch was also evaluated through in vitro hemolytic and in vivo irritation tests which were confirmed by histopathological examinations. The results showed that all formulations showed desired physical and bioadhesive properties with a folding endurance of >300 folds. The results exhibited that 31.31 ± 5.25% and 22.55 ± 4.35% of primaquine were released from transdermal patches following the in vitro and the ex vivo permeation studies. Combined with Dermaroller®, the ex vivo permeation study showed an improved permeation profile with 45.89 ± 5.00% of primaquine permeated after 24 h with a zero-order kinetic during the first 8 h. Hemolysis percentage was found to be <5%, indicating the non-toxic of this approach. Finally, the histopathology study showed that there was no severe tissue damage following the administration of our approach. Further in vivo evaluations should be performed.

Bacterial cellulose adhesive composites for oral cavity applications

Topical approaches to oral diseases require frequent dosing due to limited retention time. A mucoadhesive drug delivery platform with extended soft tissue adhesion capability of up to 7 days is proposed for on-site management of oral wound. Bacterial cellulose (BC) and photoactivated carbene-based bioadhesives (PDz) are combined to yield flexible film platform for interfacing soft tissues in dynamic, wet environments. Structure-activity relationships evaluate UV dose and hydration state with respect to adhesive strength on soft tissue mimics. The bioadhesive composite has an adhesion strength ranging from 7 to 17 kPa and duration exceeding 48 h in wet conditions under sustained shear forces, while other mucoadhesives based on hydrophilic macromolecules exhibit adhesion strength of 0.5-5 kPa and last only a few hours. The work highlights the first evaluation of BC composites for mucoadhesive treatments in the buccal cavity.

Cyclodextrin as Functional Carrier in Development of Mucoadhesive Tablets Containing Polygoni cuspidati Extract with Potential for Dental Applications

Polygoni cuspidati root is a resveratrol-rich source with anti-inflammatory, angiogenic and neuroprotective effects. The raw material was standardized for the content of resveratrol, for which there is a special justification for administration within the oral mucosa. To improve the solubility of resveratrol and to assure its high content in plant material, an ultrasound-assisted extraction method was applied. The addition of cyclodextrin was found to increase the extraction efficiency of resveratrol (from 13 to 297 µg per 1 g of plant material in case of 50% ethanol extracts) and enhanced its antioxidant activity as compared to pure Polygoni cuspidati extract/resveratrol. Cyclodextrin plays the role of a functional extract regarding technological properties (increasing the extraction of resveratrol from the extract, improving mucoadhesive properties). Therefore, the aim of this study was to develop mucoadhesive tablets containing combinations of the Polygoni cuspidati extract with a cyclodextrin carrier for buccal delivery. The tests sequentially included extract preparation and characterization of its physical and biological properties and then formulation studies with a broad description of the prototype properties. The test results indicate that cyclodextrin increases the efficiency of resveratrol extraction from Polygoni cuspidati rhizome, which is a rich source of resveratrol, and its extract enclosed in a mucoadhesive tablet guarantees prolonged action at the site of administration.

Hyaluronic Acid Hydrogels for Controlled Pulmonary Drug Delivery-A Particle Engineering Approach

Hydrogels warrant attention as a potential material for use in sustained pulmonary drug delivery due to their swelling and mucoadhesive features. Herein, hyaluronic acid (HA) is considered a promising material due to its therapeutic potential, the effect on lung inflammation, and possible utility as an excipient or drug carrier. In this study, the feasibility of using HA hydrogels (without a model drug) to engineer inhalation powders for controlled pulmonary drug delivery was assessed. A combination of chemical crosslinking and spray-drying was proposed as a novel methodology for the preparation of inhalation powders. Different crosslinkers (urea; UR and glutaraldehyde; GA) were exploited in the hydrogel formulation and the obtained powders were subjected to extensive characterization. Compositional analysis of the powders indicated a crosslinked structure of the hydrogels with sufficient thermal stability to withstand spray drying. The obtained microparticles presented a spherical shape with mean diameter particle sizes from 2.3 ± 1.1 to 3.2 ± 2.9 μm. Microparticles formed from HA crosslinked with GA exhibited a reasonable aerosolization performance (fine particle fraction estimated as 28 ± 2%), whereas lower values were obtained for the UR-based formulation. Likewise, swelling and stability in water were larger for GA than for UR, for which the results were very similar to those obtained for native (not crosslinked) HA. In conclusion, microparticles could successfully be produced from crosslinked HA, and the ones crosslinked by GA exhibited superior performance in terms of aerosolization and swelling.

Improved Bioavailability of Poorly Soluble Drugs through Gastrointestinal Muco-Adhesion of Lipid Nanoparticles

Gastrointestinal absorption remains indispensable in the systemic delivery of most drugs, even though it presents several challenges that, paradoxically, may also provide opportunities that can be exploited to achieve maximal bioavailability. Drug delivery systems made from nanoparticle carriers and especially, lipid carriers, have the potential to traverse gastrointestinal barriers and deploy in the lymphatic pathway, which aptly, is free from first pass via the liver. Several poorly soluble drugs have presented improved systemic bioavailability when couriered in lipid nanoparticle carriers. In this review, we propose an additional frontier to enhancing the bioavailability of poorly soluble drugs when encapsulated in lipid nano-carriers by imparting muco-adhesion to the particles through application of appropriate polymeric coating to the lipid carrier. The combined effect of gastrointestinal muco-adhesion followed by lymphatic absorption is a promising approach to improving systemic bioavailability of poorly soluble drugs following oral administration. Evidence to the potential of this approach is backed-up by recent studies within the review.

A review: Gelatine as a bioadhesive material for medical and pharmaceutical applications

Bioadhesive polymers offer versatility to medical and pharmaceutical inventions. The incorporation of such materials to conventional dosage forms or medical devices may confer or improve the adhesivity of the bioadhesive systems, subsequently prolonging their residence time at the site of absorption or action and providing sustained release of actives with improved bioavailability and therapeutic outcomes. For decades, much focus has been put on scientific works to replace synthetic polymers with biopolymers with desirable functional properties. Gelatine has been considered one of the most promising biopolymers. Despite its biodegradability, biocompatibility and unique biological properties, gelatine exhibits poor mechanical and adhesive properties, limiting its end-use applications. The chemical modification and blending of gelatine with other biomaterials are strategies proposed to improve its bioadhesivity. Here we discuss the classical approaches involving a variety of polymer blends and composite systems containing gelatine, and gelatine modifications via thiolation, methacrylation, catechol conjugation, amination and other newly devised strategies. We highlight several of the latest studies on these strategies and their relevant findings.

Functionalized polymeric patch for localized oxaliplatin delivery to treat gastric cancer

Localized delivery of chemotherapeutic agents allows extended drug exposure at the target site, thereby reducing systemic toxicity. We report the development of functionalized polymeric patch with unidirectional drug release to treat gastric cancer. The oxaliplatin-loaded patch was prepared by incorporating sodium carboxymethyl cellulose, hydroxypropyl cellulose and polyvinylpyrrolidone. The patch was functionalized by coating with transferrin-poly(lactic-co-glycolic acid) conjugate on one side of the patch for cancer targeting. The other side of the patch was coated with ethylcellulose (EC) to restrict the release of oxaliplatin. The physical and mechanical properties of oxaliplatin-loaded patches were characterized. Mucoadhesion studies using excised rat stomach tissue have shown that the functionalized side of the patch has significantly (p < 0.05) greater mucoadhesion strength compared with EC coated side of the patch. The in vitro and ex vivo (stomach sac and open-membrane model) studies revealed greater permeation of oxaliplatin across the stomach tissue when adhered to the functionalized and non-functionalized side of the patch compared with EC coated side. It was found that the growth inhibition with oxaliplatin solution was not significantly greater compared with corresponding concentrations of oxaliplatin-loaded patch in AGS and Caco-2 cell models. The in vivo studies were performed in mice, where indocyanine green-loaded patch encapsulated in a gelatin capsule was orally administered. The near-infrared (NIR) optical imaging revealed adherence of the patch on the mucosal side of the stomach tissue for up to 6 h. In conclusion, the functionalized polymeric patch loaded with oxaliplatin can be a potential localized delivery system to target gastric cancer.

Mucosal drug delivery and 3D printing technologies: A focus on special patient populations

In the last decade, additive manufacturing (AM) technologies have revolutionized how healthcare provision is envisioned. The rapid evolution of these technologies has already created a momentum in the effort to address unmet personalized needs in large patient groups, especially those belonging to sensitive subgroup populations (e.g., paediatric, geriatric, visually impaired). At the same time, AM technologies have become a salient ally to overcome defined health challenges in drug formulation development by addressing not only the requirement of personalized therapy, but also problems related to lowering non-specific drug distribution and the risk of adverse reactions, enhancing drug absorption and bioavailability, as well as ease of administration and patient compliance. To this end, mucoadhesive drug delivery systems fabricated with the support of AM technologies provide competitive advantages over conventional dosage forms, aiming to entice innovation in drug formulation with special focus on sensitive patient populations.

Improvement of Resveratrol Permeation through Sublingual Mucosa: Chemical Permeation Enhancers versus Spray Drying Technique to Obtain Fast-Disintegrating Sublingual Mini-Tablets

Resveratrol (RSV) is a natural polyphenol with several interesting broad-spectrum pharmacological properties. However, it is characterized by poor oral bioavailability, extensive first-pass effect metabolism and low stability. Indeed, RSV could benefit from the advantage of the sublingual route of administration. In this view, RSV attitudes to crossing the porcine sublingual mucosa were evaluated and promoted both by six different chemical permeation enhancers (CPEs) as well as by preparing four innovative fast-disintegrating sublingual mini-tablets by spray drying followed by direct compression. Since RSV by itself exhibits a low permeation aptitude, this could be significantly enhanced by the use of CPEs as well as by embedding RSV in a spray-dried powder to be compressed in order to prepare fast-disintegrating mini-tablets. The most promising observed CPEs (menthol, lysine and urea) were then inserted into the most promising spray-dried excipients’ compositions (RSV-B and RSV-C), thus preparing CPE-loaded mini-tablets. However, this procedure leads to unsatisfactory results which preclude the possibility of merging the two proposed approaches. Finally, the best spray-dried composition (RSV-B) was further evaluated by SEM, FTIR, XRD and disintegration as well as dissolution behavior to prove its effectiveness as a sublingual fast-disintegrating formulation.

Synthesis and Characterization of Thiolated Gum Ghatti as a Novel Excipient: Development of Compression-Coated Mucoadhesive Tablets of Domperidone

Mucoadhesive polymers represent a major part of site-specific and localized retention strategies in oral drug delivery. The present research was designed to synthesize and characterize a novel mucoadhesive carbohydrate polymer (thiolated gum ghatti; TGG), which was employed to formulate mucoadhesive tablets of domperidone using an industrially viable compression coating technique. Thiolation of gum ghatti was achieved by the ester formation (esterification) between the hydroxyl group and the carboxyl group of gum ghatti and thioglycolic acid. TGG was characterized by various physicochemical techniques such as FTIR, XRD, SEM, and DSC. In rheological studies, the observed viscosities of pure gum mucin were 45.45 and 71.75 mPa·s and those of the thiolated gum were 78.7 and 112.58 mPa·s, respectively, in water and simulated gastric fluid. A significant increase in viscosity for thiolated gum may be attributed to increased macromolecular interactions responsible for enhanced mucoadhesive potential of thiolated gum. In silico studies corroborate the role of mucin gum interaction and energetic stabilization for enhanced mucoadhesion properties of thiolated gum. Ex vivo mucoadhesion strength of gum ghatti- and TGG-coated tablets was found to be ranging between 45.77 ± 1.49 and 88.16 ± 1.75 and 115.32 ± 2.36 and 184.65 ± 2.07 mN, respectively. In an acute oral toxicity study, TGG did not show any toxicity on the vital organs of the Wistar rat and proved to be a safe polymer. TGG may be regarded as a promising polymer for developing different mucoadhesive drug delivery systems.

Recent Advances in Polymer-Based Vaginal Drug Delivery Systems

The vagina has been considered a potential drug administration route for centuries. Most of the currently marketed and investigated vaginal formulations are composed with the use of natural or synthetic polymers having different functions in the product. The vaginal route is usually investigated as an administration site for topically acting active ingredients; however, the anatomical and physiological features of the vagina make it suitable also for drug systemic absorption. In this review, the most important natural and synthetic polymers used in vaginal products are summarized and described, with special attention paid to the properties important in terms of vaginal application. Moreover, the current knowledge on the commonly applied and innovative dosage forms designed for vaginal administration was presented. The aim of this work was to highlight the most recent research directions and indicate challenges related to vaginal drug administrations. As revealed in the literature overview, intravaginal products still gain enormous scientific attention, and novel polymers and formulations are still explored. However, there are research areas that require more extensive studies in order to provide the safety of novel vaginal products.

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

The conventional oral administration of many nutraceuticals exhibits poor oral bioavailability due to the harsh gastric conditions and first-pass metabolism. Oral mucosa has been recognized as a potential site for the delivery of therapeutic compounds. The mucoadhesive formulation can adhere to the mucosal membrane through various interaction mechanisms and enhance the retention and permeability of bioactive compounds. Absorption of bioactive compounds from the mucosa can improve bioavailability, as this route bypasses the hepatic first-pass metabolism and transit through the gastrointestinal tract. The mucosal administration is convenient, simple to access, and reported for increasing the bioactive concentration in plasma. Many mucoadhesive polymers, emulsifiers, thickeners used for the pharmaceutical formulation are accepted in the food sector. Introducing mucoadhesive formulations specific to the nutraceutical sector will be a game-changer as we are still looking for different ways to improve the bioavailability of many bioactive compounds. This article describes the overview of buccal mucosa, the concept of mucoadhesion and related theories, and different techniques of mucoadhesive formulations. Finally, the classification of mucoadhesive polymers and the mucoadhesive systems designed for the effective delivery of bioactive compounds are presented.

Chlorhexidine Mucoadhesive Buccal Tablets: The Impact of Formulation Design on Drug Delivery and Release Kinetics Using Conventional and Novel Dissolution Methods

Oropharyngeal candidiasis (OPC) is a mucosal infection caused by Candida spp., and it is common among the immunocompromised. This condition is mainly treated using oral antifungals. Chlorhexidine (CHD) is a fungicidal and is available as a mouth wash and oral gel. It is used as an adjuvant in the treatment of OPC due to the low residence time of the current formulations. In this study, its activity was tested against C. albicans biofilm and biocompatibility with the HEK293 human cell line. Then, it was formulated as mucoadhesive hydrogel buccal tablets to extend its activity. Different ratios of hydroxypropyl methylcellulose (HPMC), poloxamer 407 (P407), and three different types of polyols were used to prepare the tablets, which were then investigated for their physicochemical properties, ex vivo mucoadhesion, drug release profiles, and the kinetics of drug release. The release was performed using Apparatus I and a controlled flow rate (CFR) method. The results show that CHD is biocompatible and effective against Candida biofilm at a concentration of 20 µg/mL. No drug excipient interaction was observed through differential scanning calorimetry (DSC) and Fourier-transform infrared spectroscopy (FTIR). The increase in P407 and polyol ratios showed a decrease in the swelling index and an increase in CHD in vitro release. The release of CHD from the selected formulations was 86-92%. The results suggest that chlorhexidine tablets are a possible candidate for the treatment of oropharyngeal candidiasis.

Synthesis and characterization of Chitosan-Catechol conjugates: Development and in vitro, in silico and in vivo evaluation of mucoadhesive pellets of lafutidine

Present study was aimed to synthesize and characterize Chitosan-Catechol conjugates and to design and develop mucoadhesive pellets loaded with lafutidine. SEM images indicated the presence of fibrous structures responsible for enhanced mucoadhesive potential of Chitosan-Catechol conjugates. Thermodynamic stability and amorphous nature of conjugates was confirmed by DSC and XRD studies respectively. Rheological studies were used to evaluate polymer mucin interactions wherein strong interactions between Chitosan-Catechol conjugate and mucin was observed in comparison to pristine chitosan and mucin. The mucoadhesion potential of Chitosan-Catechol (Cht-C) versus Chitosan (Cht) was assessed in silico using molecular mechanics simulations and the results obtained were compared with the in vitro and ex vivo results. Cht-C/mucin demonstrated much higher energy stabilization (∆E ≈ −65 kcal/mol) as compared to Cht/mucin molecular complex. Lafutidine-loaded pellets were prepared from Chitosan (LPC) and Chitosan-Catechol conjugates (LPCC) and were evaluated for various physical properties viz. flow, circularity, roundness, friability, drug content, particle size and percent mucoadhesion. In vitro drug release studies on LPC and LPCC pellets were performed for computing t50%, t90% and mean dissolution time. The values of release exponent from Korsmeyer-Peppas model was reported to be 0.443 and 0.759 for LPC and LPCC pellets suggesting Fickian and non-Fickian mechanism representing drug release, respectively. In vivo results depicted significant controlled release and enhanced residence of the drug after being released from the chitosan-catechol coated pellets. Chitosan-Catechol conjugates were found to be a promising biooadhesive polymer for the development of various mucoadhesive formulations.

Mucoadhesive Poloxamer-Based Hydrogels for the Release of HP-β-CD-Complexed Dexamethasone in the Treatment of Buccal Diseases

Oral lichen planus (OLP) is an ongoing and chronic inflammatory disease affecting the mucous membrane of the oral cavity. Currently, the treatment of choice consists in the direct application into the buccal cavity of semisolid formulations containing a corticosteroid molecule to decrease inflammatory signs and symptoms. However, this administration route has shown various disadvantages limiting its clinical use and efficacy. Indeed, the frequency of application and the incorrect use of the preparation may lead to a poor efficacy and limit the treatment compliance. Furthermore, the saliva clearance and the mechanical stress present in the buccal cavity also involve a decrease in the mucosal exposure to the drug. In this context, the design of a new pharmaceutical formulation, containing a steroidal anti-inflammatory, mucoadhesive, sprayable and exhibiting a sustained and controlled release seems to be suitable to overcome the main limitations of the existing pharmaceutical dosage forms. The present work reports the formulation, optimization and evaluation of the mucoadhesive and release properties of a poloxamer 407 thermosensitive hydrogel containing a poorly water-soluble corticosteroid, dexamethasone acetate (DMA), threaded into hydroxypropyl-beta-cyclodextrin (HP-β-CD) molecules. Firstly, physicochemical properties were assessed to ensure suitable complexation of DMA into HP-β-CD cavities. Then, rheological properties, in the presence and absence of various mucoadhesive agents, were determined and optimized. The hydration ratio (0.218-0.191), the poloxamer 407 (15-17 wt%) percentage and liquid-cyclodextrin state were optimized as a function of the gelation transition temperature, viscoelastic behavior and dynamic flow viscosity. Deformation and resistance properties were evaluated in the presence of various mucoadhesive compounds, being the sodium alginate and xanthan gum the most suitable to improve adhesion and mucoadhesion properties. Xanthan gum was shown as the best agent prolonging the hydrogel retention time up to 45 min. Furthermore, xanthan gum has been found as a relevant polymer matrix controlling drug release by diffusion and swelling processes in order to achieve therapeutic concentration for prolonged periods of time.

A Review: Uses of Chitosan in Pharmaceutical Forms

Chitosan is a natural polysaccharide widespread in nature. It has many unique and attractive properties for the pharmaceutical field: it is biodegradable, safe, hypoallergenic, biocompatible with the body, free of toxicity, with proven anticholesterolemic, antibacterial, and antimycotic action. In this review we highlighted the physical, chemical, mechanical, mucoadhesive, etc. properties of chitosan to be taken into account when obtaining various pharmaceutical forms. The methods by which the pharmaceutical forms based on chitosan are obtained are very extensive, and in this study only the most common ones were presented.

Advanced materials for drug delivery across mucosal barriers

Mucus is a viscoelastic gel that traps pathogens and other foreign particles to limit their penetration into the underlying epithelium. Dosage forms containing particle-based drug delivery systems are trapped in mucosal layers and will be removed by mucus turnover. Mucoadhesion avoids premature wash-off and prolongs the residence time of drugs on mucus. Moreover, mucus penetration is essential for molecules to access the underlying epithelial tissues. Various strategies have been investigated to achieve mucoadhesion and mucus penetration of drug carriers. Innovations in materials used for the construction of drug-carrier systems allowed the development of different mucoadhesion and mucus penetration delivery systems. Over the last decade, advances in the field of materials chemistry, with a focus on biocompatibility, have led to the expansion of the pool of materials available for drug delivery applications. The choice of materials in mucosal delivery is generally dependent on the intended therapeutic target and nature of the mucosa at the site of absorption. This review presents an up-to-date account of materials including synthesis, physical and chemical modifications of mucoadhesive materials, nanocarriers, viral mimics used for the construction of mucosal drug delivery systems.

A Bilayer Vaginal Tablet for the Localized Delivery of Disulfiram and 5-Fluorouracil to the Cervix

This study was performed to develop an adjuvant therapy in the form of a self-administered vaginal tablet regimen for the localized delivery of chemotherapeutic drugs. This therapy will help to reduce relapse by eradicating cancerous cells in the margin of cervical tumors. The vaginal tablet is a very common formulation that is easy to manufacture, easy to place in the vagina, and has a low cost of manufacture, making them ideal for use in developing countries. A combination of disulfiram and 5-fluorouracil, which are both off-patent drugs and provide different modes of action, were evaluated. The tablets developed were evaluated for weight variation, thickness, hardness, friability, swelling index, differential scanning calorimetry (DSC), particle morphology, in vitro drug release, and cytotoxicity on Ca-Ski cells. Both layers were designed to release both drugs concurrently for a synergistic effect. The polymer–polymer interaction between the layers was able to reduce the loss of formulation due to chitosan. While the bilayer tablet had satisfactory performance in the physicochemical tests, in vitro cell culture with Ca-Ski also showed a synergistic effect using a combination of drugs at a low dose. However, the formulation only had 24-h dose release before degradation. Further drug combinations should be evaluated in subsequent studies.

Preactivated-thiolated polyacrylic acid/1-vinyl pyrrolidone nanoparticles as nicotine carriers for smoking cessation

This study aimed to develop nicotine-loaded mucoadhesive preactivated-thiolated polymeric nanoparticles (PNPs) for smoking cessation. 2-Mercaptonicotinic acid (2MNA) was coupled as dithionicotinic acid dimer and used in the preactivation of thiolated polyacrylic acid/vinyl pyrrolidone PNPs (thiolated AA/VP PNPs). Preactivated-thiolated AA/VP PNPs were synthesized through surfactant-free emulsion polymerization and coupling reactions. The structural attributes of the preactivated-thiolated AA/VP PNPs were characterized using Fourier-transform infrared spectroscopy and proton nuclear magnetic resonance spectroscopy. The particle size and zeta potential were evaluated by dynamic light scattering evaluation. The morphology of the preactivated-thiolated AA/VP PNPs was examined using scanning electron microscopy. In addition, the mucoadhesive properties, drug loading and release, and biocompatibility of the preactivated-thiolated AA/VP PNPs were assessed. The spherical preactivated-thiolated AA/VP PNPs were successfully synthesized with a particle size of 410.3 ± 7.4 nm and a negative surface charge. The preactivated-thiolated AA/VP PNPs exhibited superior mucoadhesive properties compared with the thiolated AA/VP PNPs. Drug loading by PNP to a nicotine ratio of 1 : 1 provided desirable loading capacity and % loading efficiency of 285.7 ± 36.7 μg mg⁻¹ and 57.1 ± 7.4%, respectively. More than 50% of the nicotine contained in the PNPs was rapidly released in the first hour, followed by a sustained release for up to 12 h. Moreover, the synthesized PNPs were non-toxic to human gingival cells. Therefore, the preactivated-thiolated AA/VP PNPs may be a candidate carrier of nicotine for smoking cessation.

Preactivated-thiolated AA/VP NPs improved mucoadhesive property and prolonged nicotine release to 12 h.

Agro-waste extracted cellulose supported silver phosphate nanostructures as a green photocatalyst for improved photodegradation of RhB dye and industrial fertilizer effluents

The efficiency and reusability of photocatalysts are the dominant factors for their pragmatic use. The visible light induced semiconductor silver phosphate is a superior photocatalyst effective under visible light but its stability is still an undiscussed issue. To overcome this stability issue in this present manuscript, eco-friendly agro-waste extracted cellulose supported silver phosphate nanostructures have been designed for the first time through a simple chemical process. At first, silver phosphate nanostructures were synthesized by the co-precipitation method. Then, different weights of cellulose were added to the silver nitrate solution to form cellulose supported silver phosphate nanostructures. The photodegradation efficiency for each weight ratio was examined in which the photocatalyst Ag-8 nanostructures showed a high rate (0.024 min^-1) for degradation of Rhodamine B (RhB) using a low intensity tungsten bulb. Real sample analysis has also been carried out using this photocatalyst for the degradation of industrial fertilizer effluents. The degradation rate of all the nanostructures was found to be high in comparison to pristine silver phosphate as well as the extracted bare cellulose. The photocatalytic activity is enhanced because of the participation of cellulose as a support which makes an interface for silver phosphate and assists it in delaying the charge recombination period under visible light. To understand the photochemical reaction of electrons and holes, scavenger studies were also performed.