Mucoadhesive Systems Research Articles

Mucoadhesive alginate pastes with embedded liposomes for local oral drug delivery

Oral cancers are extremely common among adults with increasing incidences due to human papillomavirus, while treatment modalities are limited. This study aims to develop a new oral mucoadhesive delivery system based on the combination of alginate and liposomes. The polymer provides adhesion properties and induces local release of the drug-loaded carriers, while the liposomes protect the drug from degradation and improve its absorption into the cells. Three hybrid alginate/liposomes delivery systems were investigated: a hybrid paste, which presented excellent adhesive capabilities, yet fast burst release of 90% after 2h; a hybrid hydrogel, demonstrating controllable release rates of 5%, 30% or 60% after 2h but poor mucoadhesive properties. These findings led to the development of a hybrid cross-linked paste. Polymer retention studies demonstrated that 80% of the crosslinked paste was retained on tongue tissue compared to 50% retention of the non-cross-linked pastes, verifying its superior mucoadhesion. The hybrid cross-linked paste presented controllable release rate of 20% after 2h. Alginate paste incorporating doxorubicin loaded liposomes presented similar release rates and were highly effective in promoting cancer cell death. Thus, our innovative formulation, including both desired characteristics of mucoadhesion and sustained liposomes release, is an important milestone in the development of a new potential treatment for oral cancer.

An augmented delivery of the anticancer agent, curcumin, to the colon

This work describes the formulation aspects of an orally viable curcumin-containing mucoadhesive nanoparticulate system for management of colon cancer. Curcumin is documented to possess anticancer properties whilst modified citrus pectin yields a galactose functionality capable of inhibiting the growth and proliferation of colon cancer cells due to antagonism to galectin-3 (Gal-3). A successfully formulated curcumin containing chitosan-modified citrus pectinate nanoparticles (MCPCNPs) registered a z-average of 178nm (±0.896) and a positive surface charge of +35.7mV (±1.41). The MCPCNPs presented high mucoadhesion propensity in the colonic region/media and minimal at pH1.2 (stomach). There was approximately 18% curcumin release at pH1.2 over 2h and up to 68% release in the 33% (w/v) caecal medium over 24h. The data obtained strongly suggests that the formulated MCPCNPs have the potential to be applied as an orally deliverable colon cancer formulation alternative in the treatment of colon cancer.

Development of a mucoadhesive delivery system for control release of doxepin with application in vaginal pain relief associated with gynecological surgery

The main purpose of this study was to develop a semisolid mucoadhesive formulation for the non-invasive vaginal administration of doxepin (DOX) for relief of pain derived from the scarring process after surgery. An orafix® platform loading DOX was tested for adequate stability, rheology and vaginal mucoadhesion capacity. The formulation exhibited appropriate pH and was microbiologically stable. The rheological studies confirmed its pseudoplastic and thixotropic nature with prevalence of the elastic behavior component over the viscous one. Appropriate syringeability and spreadability results were also confirmed. Different experiments showed adequate mucoadhesion capacity even in the presence of simulated vaginal fluid. Finally, DOX release, permeation and retention in vaginal mucosa studies were also accomplished with promising results. DOX release kinetics followed the modified Higuchi model and the permeation studies did not render such high values as to suggest potential systemic absorption which could lead to undesirable systemic side effects. Therefore, we can hypostatize that the proposed formulation may assist to fill in the therapeutic gap regarding pure pain relief at local level in vagina.

Pharmaceutical Formulations to Increase Gastric Residence Time: Concepts and Strategies

Background and Objective: Gastroretentive dosage forms have emerged as efficient means for oral controlled delivery of several drugs. The objective of this review is to bring under one umbrella, all the necessary knowledge regarding gastroretentive dosage forms, especially floating dosage forms. Methods: The review covers basic anatomy and physiology of gastrointestinal tract, gastric emptying and related problems in drug absorption, candidate drugs and drugs unsuited for gastroretentive formulations, pharmacokinetics of gastroretentive formulations and factors affecting gastric residence time of dosage forms. Various approaches coined by different researchers to achieve prolonged gastric residence time like low density floating systems, high density sinking systems, modified shape systems, size controlled systems, muco-adhesive systems and magnetic systems are also detailed. Special emphasize is given to floating dosage forms, their advantages, disadvantages, excipients used in the formulation, critical parameters and methods of evaluation. Conclusion: The article is expected to motivate the researchers to investigate on gastroretentive dosage forms systematically. Keywords: Gastroretentive, floating, mucoadhesive, drug delivery, bioavailability, stomach specific.

Buccal patches of atenolol formulated using fenugreek (Trigonella foenum-graecum L.) seed mucilage.

The use of mucoadhesive natural polymers in designing mucoadhesive patch systems has received much attention. The study involved the development and evaluation of buccal patches of atenolol using fenugreek (Trigonella foenum-graecum L.) seed mucilage with hydroxylpropyl methyl cellulose (HPMC K4M) and a backing membrane (ethyl cellulose 5% w/v). These atenolol-releasing buccal patches were prepared using a solvent casting technique. The buccal patches prepared were evaluated for average weight, thickness, drug content, folding endurance and moisture content. Ex vivo mucoadhesive strength, force of adhesion and bonding strength were determined using porcine buccal mucosa. The mucosal permeation of atenolol through the porcine buccal mucosa was carried out using a Franz diffusion cell in phosphate buffer saline, pH 6.8. These buccal patches were also characterized by SEM and FTIR spectroscopy. The average weight, thickness, drug content, folding endurance and moisture content of these atenolol-releasing buccal patches were found satisfactory for all the patches. Amongst all, the F-4 buccal patch showed maximum mucoadhesive strength (31.12 ±1.86 g), force of adhesion (30.53 × 10-2 N) and bond strength (1748.89 N/m2). Ex vivo atenolol permeation from the buccal patches showed drug permeation across the excised porcine buccal mucosa over 12 h. The F-4 buccal patch showed maximum permeation flux (29.12 μg/cm2/h). The developed atenolol-releasing buccal patches can be beneficial over the conventional drug delivery systems to decrease the dosing frequency and enhance patient compliance.

Chitosan microencapsulation of the dispersed phase of an O/W nanoemulsion to hydrochlorothiazide delivery

In view of biopharmaceutical limitations of hydrochlorothiazide (HCTZ), Trojan-type mucoadhesive systems were proposed, aiming to improve HCTZ pharmacological properties by modulating its release. Nanoemulsions were formed spontaneously by combining medium-chain triglycerides (Lipoid® S75 and Pluronic® F68) and high encapsulation efficiency was obtained. The mucoadhesive properties were provided by chitosan and microencapsulation of nanoemulsions in spray-dryer was successfully achieved by using Aerosil® as wall material. The rapid redispersion of nanoemulsion in simulated fluids led to a fast and complete release of HCTZ in gastric medium. The pharmacodynamics of HCTZ was improved, extending the diuretic activity. Once a simple and low-energy method contributed to obtain stable mucoadhesive nanoemulsions, advantages in terms of production could also be achieved, allowing easy scaling up. This novel mucoadhesive Trojan particulate system of HCTZ showed to be a promising approach to overcome limitations in terms of absorption and consequently improve the therapeutic efficacy.

New biomaterials and ocular drug delivery

SummaryThe need for new methods of delivering pharmacologically active agents to the eye has never been greater with the growing incidence of ocular disorders. Polymeric drug delivery methods show great promise for enhancing drug residence time as well as convenience for the patient. This talk will focus on three novel polymer based drug delivery systems developed in our labs. A mucoadhesive micelle system has been developed using acceptable polymers and has been shown to enhance the on eye residence time and the delivery of cyclosporine A in the treatment of dry eye disease. A transparent, in situ gelling injectable system has been examined to enhance the delivery of various drugs for treating diseases of the back of the eye. Finally, a Vitamin E based system is injectable, gelling upon exposure to aqueous conditions will be described. The potential of these systems as well as their limitations will be discussed and next steps in their development with a goal of creating a clinically viable drug delivery system will be described.

Novel solidified reverse micellar solution-based mucoadhesive nano lipid gels encapsulating miconazole nitrate-loaded nanoparticles for improved treatment of oropharyngeal candidiasis

Objective: To develop and evaluate solidified-reverse-micellar-solution (SRMS)-based oromucosal nano lipid gels for improved localised delivery of miconazole nitrate (MN).Methods: Phospholipon® 90G and Softisan® 154 (3:7) were used to prepare SRMS by fusion. Solid lipid nanoparticles (SLNs, 0.25–1.0% w/w MN) formulated with the SRMS by high shear homogenisation were employed to prepare mucoadhesive nano lipid gels. Physicochemical characterisation, drug release in simulated salivary fluid (SSF) (pH 6.8) and anti-candidal activity were carried out.Results: The SLNs were spherical nanoparticles, had mean size of 133.8 ± 6.4 to 393.2 ± 14.5 nm, low polydispersity indices, good encapsulation efficiency (EE) (51.96 ± 2.33–67.12 ± 1.65%) and drug loading (DL) (19.05 ± 2.44–24.93 ± 1.98%). The nano lipid gels were stable, spreadable, pseudoplastic viscoelastic mucoadhesive systems that exhibited better prolonged release and anti-candidal properties than marketed formulation (Daktarin® oral gel) (p < 0.05).Conclusion: This study has shown that SRMS-based nano lipid gels could be employed to prolong localised oromucosal delivery of MN.

Alginate modified with maleimide-terminated PEG as drug carriers with enhanced mucoadhesion

The goal of this study was to generate a new mucoadhesive carbohydrate-based delivery system composed of alginate (Alg) backbone covalently attached to polyethylene glycol (PEG) modified with a unique functional end-group (maleimide). The immobilization of PEG-maleimide chains significantly improved the mucoadhesion properties attributed to thioether bonds creation via Michael-type addition and hydrogen bonding with the mucus glycoproteins. Mucoadhesion studies using tensile and rotating cylinder assays revealed a 3.6-fold enhanced detachment force and a 2.8-fold enhanced retention time compared to the unmodified polymer, respectively. Additional indirect studies confirmed the presence of polymer-mucus glycoproteins interactions.Drug release experiments were used to evaluate the release profiles from Alg-PEG-maleimide tablets in comparison to Alg and Alg-SH tablets. Viability studies of normal human dermal fibroblasts cells depicted the non-toxic nature of Alg-PEG-maleimide. Overall, our studies disclose that PEG-maleimide substitutions on other biocompatible polymers can lead to the development of useful biomaterials for diverse biomedical applications.

Novel ex vivo protocol using porcine vagina to assess drug permeation from mucoadhesive and colloidal pharmaceutical systems

Local treatment of vaginal diseases presents advantages over systemic treatments and the interaction of the drug delivery systems with the biological tissue is a key factor for a successful vaginal topical therapy. Conventional protocols for permeation studies have high variability and fail in distinguishing drug penetration from mucoadhesive or colloidal drug delivery systems from conventional formulations, as tissue interaction is normally under estimated. The protocol presented in this paper is a simplified ex vivo vertical model, in which formulations are placed in hung porcine vaginas with the objective of mimicking a condition closer to the biological circumstance, specifically considering the possible leak from the vaginal canal in the vertical position. The results indicate the proposed method was capable of differentiating formulations performances and histological evaluation showed mucosa structures are preserved during this new assay. Therefore, the ex vivo method can be considered reliable for approaching the physiological situation in comparative studies.

Innovative Methods and Applications in Mucoadhesion Research.

The present review is aimed at elucidating relatively new aspects of mucoadhesion/mucus interaction and related phenomena that emerged from a Mucoadhesion workshop held in Munster on 2-3 September 2015 as a satellite event of the ICCC 13th-EUCHIS 12th. After a brief outline of the new issues, the focus is on mucus description, purification, and mucus/mucin characterization, all steps that are pivotal to the understanding of mucus related phenomena and the choice of the correct mucosal model for in vitro and ex vivo experiments, alternative bio/mucomimetic materials are also presented. Then a selection of preparative techniques and testing methods are described (at molecular as well as micro and macroscale) that may support the pharmaceutical development of mucus interactive systems and assist formulators in the scale-up and industrialization steps. Recent applications of mucoadhesive systems (including medical devices) intended for different routes of administration (oral, gastrointestinal, vaginal, nasal, ocular, and intravesical) and for the treatment of difficult to treat pathologies or the alleviation of symptoms are described.

A Comprehensive Review on Buccal DrugDelivery System

Buccal delivery involves the administration of the desired drug through the buccal mucosal membrane lining of the oral cavity. The objective of this article is to review buccal drug delivery by discussing the structure and environment of the oral mucosa and highlighting the mechanisms of drug permeation and methodology in evaluating buccal formulations. This review also highlights a brief description of advantages, limitations of buccal drug delivery and theories involved in mucoadhesion along with method of preparation mucoadhesive system, mucoadhesive polymer, and classification of buccal system.

Natural dendrimers: Synthesis and in vitro characterization of glycogen-cysteamine conjugates

The aim of this study was to synthesize, characterize and evaluate the mucoadhesive properties of the first thiolated hyperbranched natural polysaccharide with biodegradability and biocompatibility features. In detail, glycogen-cysteamine conjugates were synthesized through a first step of oxidative ring opening applying increasing concentrations of sodium periodate, to obtain polymers with different degrees of oxidation, and a second step of reductive amination with a constant amount of cysteamine. The obtained glycogen-cysteamine conjugates were characterized regarding their content of free and total thiol groups by Ellman’s assay, biocompatibility, swelling/erosion behavior, rheological synergism and mucoadhesive properties in comparison to the unmodified glycogen. The higher the concentration of periodate was, the higher was the content of total thiol groups being in the range of 255.7±12–1194.5±82μmol/g, biocompatibility remained unaffected by these structural changes. On the contrary, the mucoadhesive properties, evaluated by tensile, rheological synergism and rotating cylinder studies, appear to be influenced by the thiol groups concentration on the glycogen. In particular the glycogen-cysteamine conjugate exhibiting the highest degree of thiolation showed a 79-fold increase in viscosity over a time period of 8h, as well as, remained attached on freshly excised porcine mucosa 32-fold longer than the unmodified polymer. The higher was the amount of conjugated thiol groups, the higher was the water absorption capacity of glycogen-cysteamine tablets in Simulated Intestinal Fluid pH 6.8 (SIF). The introduction of thiol moieties on polymer changed the characteristics of the polysaccharide by improving mucoadhesion properties. Therefore, this work represents the first study describing thiolated natural dendrimers as potential platform useful to realize appropriate mucoadhesive nanocarrier systems suitable to prolong mucosal residence time.

Quality by Design approach for an in situ gelling microemulsion of Lorazepam via intranasal route

The present study illustrates the application of the concept of Quality by Design for development, optimization and evaluation of Lorazepam loaded microemulsion containing ion responsive In situ gelator gellan gum and carbopol 934. A novel approach involving interactions between surfactant and polymer was employed to achieve controlled drug release and reduced mucociliary clearance. Microemulsion formulated using preliminary solubility study and pseudo ternary phase diagrams showed significantly improved solubilization capacity of Lorazepam with 54.31±6.07nm droplets size. The effect of oil to surfactant/cosurfactant ratio and concentration of gelling agent on the drug release and viscosity of microemulsion gel (MEG) was evaluated using a 32 full factorial design. The gel of optimized formulation (MEG1) showed a drug release up to 6h of 97.32±1.35% of total drug loaded. The change in shear-dependent viscosity for different formulations on interaction with Simulated Nasal Fluid depicts the crucial role of surfactant-polymer interactions on the gelation properties along with calcium ions binding on the polymer chains. It is proposed that the surfactant-polymer interactions in the form of a stoichiometric hydrogen bonding between oxyethylene and carboxylic groups of the polymers used, provides exceptional ME stability and adhesion properties. Compared with the marketed formulation, optimized MEG showed improved pharmacodynamic activity. Ex vivo diffusion studies revealed significantly higher release for MEG compared to microemulsion and drug solution. MEG showed higher flux and permeation across goat nasal mucosa. According to the study, it could be concluded that formulation would successfully provide the rapid onset of action, and decrease the mucociliary clearance due to formation of in situ gelling mucoadhesive system.

Mucoadhesive Polymers and Their Mode of Action: A Recent Update

The potential of mucoadhesive delivery system for sustained delivery of drug has been established few decades back. Different polymeric systems such as single or combined, substituted, conjugated, pre-activated polymer (s) etc. are used to develop such delivery platform. To explain the mucoadhesion mechanism, several possible theories namely electronic theory, adsorption theory, wetting theory, diffusion theory, fraction theory and mechanical theory has been proposed. But none of these theories alone can explain the mechanism of mucoadhesion. Various mechanism of mucoadhesion or bioadhesion between polymer and mucin such as H bonding, electrostatic interactions, di-sulfide linkage, van Der Waals attraction etc have been evidenced. Researches are focused to enrich such interaction between the mucous layer and the delivery platform by modifying the system. Wide varieties of polymers such as cationic, anionic, non-ionic, thiolated polymers etc have been used to design and develop mucoadhesive drug delivery system. Therefore reviewing and analyzing the mucoadhesive polymeric system and their mechanism of action is still relevant and necessary. The aim of this current review is to highlight the polymers which are being used under recent scientific researches with emphasis on their mechanism of mucoadhesion. The outcome of this review will help researchers to screen the mucoadhesive polymers for their intended use.

Vaginal Delivery of Benzydamine Hydrochloride through Liposomes Dispersed in Mucoadhesive Gels.

Liposomal vaginal drug delivery systems are important strategy in the treatment of both topical and systemic diseases. The aim of this study was to develop a vaginal delivery system for benzydamine hydrochloride (BNZ) loaded liposomes dispersed into mucoadhesive gels. The delivery system was also designed for a once a day dosage and to obtain controlled release of the BNZ. For this purpose BNZ containing gel formulations using hydroxypropyl methylcellulose (HPMC) K100M and Carbopol® 974P, which are composed of polymers that show promising potential as mucoadhesive vaginal delivery systems, were developed. In addition, a BNZ containing liposome formulation was developed for vaginal administration. To improve the vaginal retention time, liposome was incorporated in HPMC K100M and Carbopol® 974P gel formulations. This system is called lipogel. The developed BNZ liposomes have a slightly negative zeta potential (-1.50±0.16 mV), a 2.25±0.009 µm particle size and a 34% entrapment efficiency. These gels and lipogels have appropriate pH, viscosity, textural properties and mucoadhesive value for vaginal administration. Lipogels were found to be the best formulations for in vitro diffusion and ex vivo mucoadhesion. The work of mucoadhesion obtained from liposomes was in the range of 0.027±0.045 and 0.030±0.017 mJ/cm2, while the value obtained from lipogels was between 0.176±0.037 and 0.243±0.53 mJ/cm2. N1 and N2 lipogel formulations diffused 57 and 67% of BNZ respectively at the end of 24 h. Moreover, a higher mucoadhesion, which increases drug residence time in comparison to liposomes, could improve BNZ efficacy. In conclusion, BNZ mucoadhesive vaginal lipogel formulations can be promising alternatives to traditional dosage forms for vaginal topical therapy.

Mucoadhesive Chitosan-Pectinate Nanoparticles for the Delivery of Curcumin to the Colon.

In the present study, we report the properties of a mucoadhesive chitosan-pectinate nanoparticulate formulation able to retain its integrity in the milieu of the upper gastrointestinal tract and subsequently, mucoadhere and release curcumin in colon conditions. Using this system, we aimed to deliver curcumin to the colon for the possible management of colorectal cancer. The delivery system comprised of a chitosan-pectinate composite nanopolymeric with a z-average of 206.0nm (±6.6nm) and zeta potential of +32.8mV (±0.5mV) and encapsulation efficiency of 64%. The nanoparticles mucoadhesiveness was higher at alkaline pH compared to acidic pH. Furthermore, more than 80% release of curcumin was achieved in pectinase-enriched medium (pH 6.4) as opposed to negligible release in acidic and enzyme-restricted media at pH 6.8. SEM images of the nanoparticles after exposure to the various media indicate a retained matrix in acid media as opposed to a distorted/fragmented matrix in pectinase-enriched medium. The data strongly indicates that the system has the potential to be applied as a colon-targeted mucoadhesive curcumin delivery system for the possible treatment of colon cancer.

Fungal diseases: could nanostructured drug delivery systems be a novel paradigm for therapy?

Invasive mycoses are a major problem for immunocompromised individuals and patients in intensive care units. Morbidity and mortality rates of these infections are high because of late diagnosis and delayed treatment. Moreover, the number of available antifungal agents is low, and there are problems with toxicity and resistance. Alternatives for treating invasive fungal infections are necessary. Nanostructured systems could be excellent carriers for antifungal drugs, reducing toxicity and targeting their action. The use of nanostructured systems for antifungal therapy began in the 1990s, with the appearance of lipid formulations of amphotericin B. This review encompasses different antifungal drug delivery systems, such as liposomes, carriers based on solid lipids and nanostructure lipids, polymeric nanoparticles, dendrimers, and others. All these delivery systems have advantages and disadvantages. Main advantages are the improvement in the antifungal properties, such as bioavailability, reduction in toxicity, and target tissue, which facilitates innovative therapeutic techniques. Conversely, a major disadvantage is the high cost of production. In the near future, the use of nanosystems for drug delivery strategies can be used for delivering peptides, including mucoadhesive systems for the treatment of oral and vaginal candidiasis.

Mucoadhesive Buccal Films Based on Chitosan and Carboxymethylated Feronia Limonia Fruit Pulp Mucilage Interpolymer Complex for delivery of Opioid Analgesics

Aim: To develop and evaluate interpolymer complex (IPC) based buccal mucoadhesive films for delivery of opioid analgesics. The IPC was prepared using Chitosan and carboxymethylated Feronia limonia fruit pulp mucilage. Materials and Methods: In this study, the IPC is formed between mucoadhesive polymer chitosan and carboxymethylated F. limonia fruit pulp mucilage. The resulted IPC is used to prepare buccal mucoadhesive films of a model opioid analgesic. Other excipients include glycerin as plasticizer, a combination of sodium dihydrocholate and ethylenediaminetetraacetic acid sodium salt as permeation enhancers and a backing layer of 1% ethyl cellulose is placed on each film to ensure unidirectional drug release to systemic circulation. The solvent casting method is used to prepare buccal films and evaluated for bioadhesion strength, tensile strength, swelling index, ex vivo diffusion, and in vitro dissolution. Results and Discussion: Formulations are prepared and optimized by 32 factorial design. Formulation F7 was found to be optimized formulation which contained 50 mg drug, 100 mg IPC, and 2% glycerin as plasticizer. Thus, this study suggests that IPC between chitosan and carboxymethylated F. limonia fruit pulp mucilage can act as a potential mucoadhesive polymer system for buccal delivery of opioid analgesic drugs. Conclusion: In this study novel, buccoadhesive film was developed using IPC between chitosan and carboxymethylated F. limonia fruit pulp mucilage. The film was releasing drug over a period of 8-h directly to systemic circulation through buccal mucosa. The extensive first pass metabolism of a drug was prevented to a great extent.

Mucoadhesive systems in dentistry: A review

For any treatment plan to succeed, two factors are paramount correct selection and application of pharmacologic agents and patient compliance. But what happens when both these are followed judiciously, but the medicine itself does not stay long enough to finish its action? Then we need something that will make the medicine stick literally. That is when bioadhesives have their say. Long-term adhesion of drugs to the oral mucosa is usually prevented by the continuous salivary flow and the mechanical movements of the tongue. Therefore, formulations acting as vehicle for local drug delivery to the oral mucosa need to have excellent mucoadhesive properties. The present article reviews mucoadhesive systems with various formulations that can be used in dentistry to improve local drug delivery.