The correlation between zeta potential and mucoadhesion strength on pig vesical mucosa

Coating with tripolyphosphate-crosslinked chitosan as a novel approach for enhanced stability of emulsomes following oral administration: Rutin as a model drug with improved anti-hyperlipidemic effect in rats

The aim of the current study is to preserve the emulsomal vesicles against the harsh condition of gastrointestinal tract (GIT), after oral administration, employing tripolyphosphate (TPP)-crosslinked chitosan as a protective coating layer. Rutin was used as a model drug with evaluation of anti-hyperlipidemic activity in rats. The rutin loaded unmodified emulsomes were prepared using tripalmitin and soybean phosphatidylcholine (SPC), by thin film method. Drug loading for the prepared formulations ranged between 6.80 and 15.50 %. The selected formulation (RT-Emuls-6) comprised tripalmitin and SPC, molar ratio 1:1, and exhibited particle size (PS) and zeta potential (ZP) of 150.40 nm and -35.35 mV, respectively. RT-Emuls-6 was then modified by coating with either solely chitosan (RT-Emuls-6-Ch) or TPP-crosslinked chitosan (RT-Emuls-6-Ch-TPP-1). The latter exhibited PS and ZP values of 269.60 nm and 37.17 mV, respectively. Transmission electron microscopy of RT-Emuls-6-Ch-TPP-1 showed a dense pale greyish layer of a coating layer of chitosan crosslinked with TPP surrounding SPC bilayers. Fourier transform infrared spectroscopy analysis along with X-ray powder diffraction confirmed cross-linking between chitosan and TPP. Stability study in the simulated GIT fluids revealed that the order of rutin retained percentage was RT-Emuls-6-Ch-TPP-1 > RT-Emuls-6-Ch > RT-Emuls-6 (80.02, 50.66 and 44.41 %, respectively for simulated gastric fluid and 63.50, 55.66 and 24.00 %, respectively for simulated intestinal fluid, after 2 h incubation). Anti-hyperlipidemic activity of rutin loaded emulsomes was evaluated, after oral administration, in a high fat diet-induced hyperlipidemia in rats. The order of activity was as follows: RT-Emuls-6-Ch-TPP-1 > RT-Emuls-6-Ch > RT-Emuls-6 > free rutin. These findings revealed the potential of TPP-crosslinked chitosan as a protective coating layer for enhancing the stability of emulsomes against the harsh condition of GIT. RT-Emuls-6-Ch-TPP-1 had a potent anti-hyperlipidemic activity via regulation of lipids, oxidative stress, irisin and uncoupling protein 1.

Modification of chicha gum: Antibacterial activity, ex vivo mucoadhesion, antioxidant activity and cellular viability

The aim of the present work was to modify the exuded gum of Sterculia striata tree by an amination reaction. The viscosity and zero potential of the chicha gum varied as a function of pH. The modification was confirmed by X-ray diffraction (XRD), infrared spectroscopy (FTIR), size exclusion chromatography (SEC), zeta potential, thermogravimetric analysis (TG), and differential scanning calorimetry (DSC). Furthermore, the chemical modification changed the molar mass and surface charge of the chicha gum. In addition, the gums were used in tests for ex vivo mucoadhesion strength, antibacterial activity against the standard strain of Staphylococcus aureus (ATCC 25923), inhibitory activity of α-glucosidase, antioxidant capacity, and viability of Caco-2 cells. Through these tests, it was found that amination caused an increase in the mucoadhesive and inhibitory activity of chicha gum against the bacterium Staphylococcus aureus. In addition, the gums (pure and modified) showed antioxidant capacity and an inhibitory effect against the α-glucosidase enzyme and did not show cytotoxic potential.

Biopolymer from Water Kefir as a Potential Clean-Label Ingredient for Health Applications: Evaluation of New Properties

The present work aimed to characterize the exopolysaccharide obtained from water kefir grains (EPSwk), a symbiotic association of probiotic microorganisms. New findings of the technological, mechanical, and biological properties of the sample were studied. The EPSwk polymer presented an Mw of 6.35 × 10⁵ Da. The biopolymer also showed microcrystalline structure and characteristic thermal stability with maximum thermal degradation at 250 °C. The analysis of the monosaccharides of the EPSwk by gas chromatography demonstrated that the material is composed of glucose units (98 mol%). Additionally, EPSwk exhibited excellent emulsifying properties, film-forming ability, a low photodegradation rate (3.8%), and good mucoadhesive properties (adhesion Fmax of 1.065 N). EPSwk presented cytocompatibility and antibacterial activity against Escherichia coli and Staphylococcus aureus. The results of this study expand the potential application of the exopolysaccharide from water kefir as a potential clean-label raw material for pharmaceutical, biomedical, and cosmetic applications.

Ocular drug delivery to the anterior segment using nanocarriers: A mucoadhesive/mucopenetrative perspective

There is a growing demand for effective treatments for ocular conditions that improve patient compliance and reduce side-effects. While methods such as implants and injections have proven effective, topical administration remains the method of choice for the delivery of therapeutics to the anterior segment of the eye. However, topical administration suffers from multiple drawbacks including low bioavailability of the target therapeutic, systemic toxicity, and the requirement for high therapeutic doses due to the effective clearance mechanisms that exist in the eye. Nanoparticles that have tunable mucoadhesion and/or mucopenetration offer outstanding potential to overcome the anatomical and physiological barriers present to improve ocular bioavailability, reduce toxicity, and increase ocular retention, among other benefits. The current review highlights recent advances in the field of developing nanocarriers with tunable mucoadhesion and mucopenetration for drug delivery to the eye.

Influence of cellulose nanocrystals (CNC) on permeation through intestinal monolayer and mucus model in vitro

Cellulose nanocrystals (CNC) as a novel ingredient in foods and pharmaceuticals still lacks the safety and functionality information. We aimed to assess the absorption of CNC in small intestine and the effect on cell viability. In the second part, the impact of CNC on substance permeation through mucus layer, including the potential functionality in improving high blood cholesterol, was tested. No noticeable amount of CNC was found to penetrate through differentiated Caco-2 monolayer and in vitro mucus layer, and CNC had low toxicity on Caco-2 cell viability up to 10 mg/mL. CNC at 2 % (w/w) may affect the permeability of the mucus layer and larger molecules are more easily influenced. CNC may also alleviate hypercholesteremia by increasing viscosity of digesta, adsorbing cholesterol, and decreasing bile acids permeation. The results suggest CNC may not penetrate the small intestinal lining and may be used as a functional supplement.

Influence of Plasticizers on the pH-Dependent Drug Release and Cellular Interactions of Hydroxypropyl Methylcellulose/Zein Vaginal Anti-HIV Films Containing Tenofovir

Vaginal films featuring the pH-dependent release of tenofovir (TFV) were developed for the prevention of sexual transmission of human immunodeficiency syndrome (HIV). Films based on hydroxypropyl methylcellulose and zein were prepared incorporating different plasticizers [oleic acid, lactic acid, glycerol, and polyethylene glycol 400 (PEG)] and evaluated for in vitro drug release in an acidic simulated vaginal fluid (pH 4.2) and a slightly alkaline mixture of simulated seminal and vaginal fluids (pH 7.5). Results revealed that optimal biphasic TFV release was possible with proper combination of plasticizers (PEG and oleic acid, 1:7 w/w) and by adjusting the plasticizer/matrix-forming material ratio. The films had similar or higher levels of TFV associated with genital epithelial cells (Ca Ski or HEC-1-A cells) but lower drug permeability compared to the free drug. These data confirm that films have the potential to achieve suitable mucosal levels of TFV with low systemic exposure. The films developed could protect women from HIV sexual transmission.

Sterculia striata gum as a potential oral delivery system for protein drugs

Natural polysaccharides have been investigated as vehicles for oral insulin administration. Because of their non-toxic, renewable, low cost and readily available properties, gums find multiple applications in the pharmaceutical industry. This work aimed to develop a Sterculia striata gum-based formulation associated with additional biopolymers (dextran sulfate, chitosan, and albumin), a crosslinking agent (calcium chloride) and stabilizing agents (polyethylene glycol and poloxamer 188), to increase the oral bioavailability of proteins. Insulin was used as a model drug and the methods used to prepare the formulation were based on ionotropic pregelation followed by electrolytic complexation of oppositely charged biopolymers under controlled pH conditions. The developed formulation was characterized to validate its efficacy, by the determination of its average particle size (622 nm), the insulin encapsulation efficiency (70%), stability in storage for 30 days, and the in vitro mucoadhesion strength (92.46 mN). Additionally, the developed formulation preserved about 64% of initial insulin dose in a simulated gastric medium. This study proposed, for the first time, a Sterculia striata gum-based insulin delivery system with potential for the oral administration of protein drugs, being considered a valid alternative for efficient delivery of those drugs.

Chitosan-coated nanodiamonds: Mucoadhesive platform for intravesical delivery of doxorubicin

Nanodiamonds (NDs) are an emerging delivery system with a massive surface area qualifying them for efficient loading with various drugs. However, NDs easily scavenge ions upon mixing with physiological media leading to rapid aggregation. Herein, chitosan was employed to endue steric stabilization to NDs and confer adhesiveness to the particles improving their retention in the urinary bladder. The effect of chitosan molecular weight and pH on the particle size and surface charge of chitosan-coated doxorubicin-loaded NDs (Chi-NDX) was investigated. Selected formula exhibited high drug loading efficiency (>90 %), small particle size (<150 nm), good colloidal stability, acid-favored drug release but limited stability in cell culture media. After further stabilization with TPP or dextran sulfate, selected TPP-treated formula displayed more potent cytotoxic effect compared with free doxorubicin and uncoated nanoparticles, and higher drug retention in ex vivo bovine bladder. Therefore, TPP-Chi-NDX is suggested as a promising system for mucosal anticancer delivery.

A gellan gum derivative as in-situ gelling cationic polymer for nasal drug delivery

The aim of the present study was the development of a novel gellan gum derivative exhibiting mucoadhesive properties for nasal application. Accomplishing this, amino groups have been introduced to the polymeric backbone. The resulting synthesis products were characterized in terms of the amount of attached amino groups, regarding hydration, zeta potential and gel characteristics. Mucoadhesiveness was assessed studying rheological synergism, by rotating cylinder and regarding tensile studies. Next to erythrocyte-/cytotoxicity evaluation, the impact on ciliary beat frequency of nasal epithelial cells was investigated. Results revealed coupling rates up to 1259.50 ± 75.98 μmol/g polymer as well as accelerated hydration of the derivatives. Comparing aminated with unmodified gellan, enhanced mucoadhesion was verified by a 32-fold increase in viscosity of polymer/mucus mixtures and by a 14-fold extended mucosal adhesion time. Tensile studies demonstrated a 9-fold higher total work of adhesion and a 3.75-fold elevated maximum detachment force. Cellular membrane was not seriously impaired. CBF studies proved a reversible inhibition due to the application of the novel derivative. According to the outlined findings, aminated gellan gum can be considered as a promising excipient for nasal dosage forms improving drug bioavailability by superior adhesive features.

Rebamipide-loaded chitosan nanoparticles accelerate prostatic wound healing by inhibiting M1 macrophage-mediated inflammation via the NF-κB signaling pathway

A large proportion of benign prostatic hyperplasia (BPH) patients suffer from lower urinary tract symptoms after surgery due to the presence of prostatic urothelium wounds. Rebamipide (RBM) exerts wound healing promotion and anti-inflammatory effects on various tissues, including the urothelium. However, intravesical administration of RBM is hindered due to its low solubility and resulting unsustainable drug concentrations in the bladder. In this study, RBM-loaded chitosan nanoparticles (RBM/CTS NPs) were prepared using the ionic cross-linking method. Physicochemical characteristics and the wound healing promotion effect, as well as in vitro influence on macrophages were evaluated. The results show that RBM/CTS NPs are spherical with uniform size distribution, while slower and sustained in vitro release of RBM is presented. In vivo, faster wound healing and improved re-epithelialization progress were observed after treatment with RBM/CTS NPs in a model of thulium laser resection of the prostate (TmLRP). The degree of local inflammatory response decreased, as confirmed by decreasing numbers of pro-inflammatory M1 phenotype macrophages and levels of IL-1β, IL-6, IL-12 and TNF-α in the urine of canines. We also found that RBM/CTS NPs suppress macrophage M1 polarization induced by lipopolysaccharide and interferon-γ and inhibit the activation of the NF-κB signaling pathway. Therefore, as a novel therapeutic strategy, intravesical administration of RBM/CTS NPs can effectively avoid drug intolerance and drug wastage, accelerating the postoperative wound repairing of the prostatic urethra by suppressing macrophage M1 phenotype polarization.

Development, characterisation and nasal deposition of melatonin-loaded pectin/hypromellose microspheres

In this study, we present the development of spray-dried pectin/hypromellose microspheres as efficient melatonin carrier for targeted nasal delivery. Different pectin to hypromellose weight ratios in the spray-dried feed were employed (i.e. 1:0, 3:1, 1:1 and 1:3) in order to optimise microsphere physicochemical properties influencing overall powder behaviour prior, during and upon nasal delivery. All microspheres assured complete melatonin entrapment and increased dissolution rate in relation to pure melatonin powder. Among all combinations tested, combining pectin with hypromellose at 1:3 wt ratio resulted in the microspheres with the highest potential for melatonin nasal delivery as they assured highest swelling ability and most prominent mucoadhesive properties. Studies on deposition profile revealed adequate turbinate and olfactory deposition of microsphere/lactose monohydrate powder blend administered nasally using MIAT® device, complementing findings relevant for their therapeutic potential. In conclusion, developed microspheres bear the potential to ensure prolonged melatonin retention at the nasal mucosa, improved bioavailability and advanced therapeutic outcome.

Chitosan: The One and Only? Aminated Cellulose as an Innovative Option for Primary Amino Groups Containing Polymers

The aim of this study was the synthesis and in vitro characterization of aminated cellulose as alternative excipient to chitosan. The aldehyde form of cellulose was generated via the oxidative cleavage of vicinal diols by the addition of increasing concentrations of sodium periodate. The insertion of primary amines was achieved by reductive amination with ammonia. The degree of substitution was calculated via primary amino group quantification using a 2,4,6-trinitrobenzenesulfonic acid assay. Mucoadhesiveness was examined by adopting the rotating-cylinder method and tensile studies using porcine intestinal mucosa. Hydration was evaluated at pH 2-11. The successful formation of aldehydes as well as a subsequent introduction of up to 311.61 micromoles per gram of primary amines were proven to correlate with the amount of added periodate. There was a 3- to 14-fold prolongation in the mucosal residence time of the new polymer in comparison to chitosan, as measured by the rotating-cylinder method. Although cationic cellulose did not reach the maximum detachment force of chitosan, the total work of adhesion of the newly synthesized cellulose derivate was higher than that of chitosan. The higher the degree of amination, the higher the degree of hydration in neutral and alkaline aqueous media was. Compared to chitosan, the novel cationic cellulose derivative displays improved mucoadhesive properties as well as sufficient hydration at physiological pH. Therefore, aminated cellulose is a promising alternative to the cationic polymers, such as chitosan, used thus far.

Genetically Engineered Mucoadhesive Spider Silk

Mucoadhesion is defined as the adhesion of a material to the mucus gel covering the mucous membranes. The mechanisms controlling mucoadhesion include nonspecific electrostatic interactions and specific interactions between the materials and the mucins, the heavily glycosylated proteins that form the mucus gel. Mucoadhesive materials can be used to develop mucosal wound dressings and noninvasive transmucosal drug delivery systems. Spider silk, which is strong, biocompatible, biodegradable, nontoxic, and lightweight would serve as an excellent base for the development of such materials. Here, we investigated two variants of the partial spider silk protein 4RepCT genetically engineered in order to functionalize them with mucoadhesive properties. The pLys-4RepCT variant was functionalized with six cationically charged lysines, aiming to provide nonspecific adhesion from electrostatic interactions with the anionically charged mucins, while the hGal3-4RepCT variant was genetically fused with the Human Galectin-3 Carbohydrate Recognition Domain which specifically binds the mucin glycans Galβ1-3GlcNAc and Galβ1-4GlcNAc. First, we demonstrated that coatings, fibers, meshes, and foams can be readily made from both silk variants. Measured by the adsorption of both bovine submaxillary mucin and pig gastric mucin, the newly produced silk materials showed enhanced mucin binding properties compared with materials of wild-type (4RepCT) silk. Moreover, we showed that pLys-4RepCT silk coatings bind mucins through electrostatic interactions, while hGal3-4RepCT silk coatings bind mucins through specific glycan-protein interactions. We envision that the two new mucoadhesive silk variants pLys-4RepCT and hGal3-4RepCT, alone or combined with other biofunctional silk proteins, constitute useful new building blocks for a range of silk protein-based materials for mucosal treatments.

Spray-Dried Thiolated Chitosan-Coated Sodium Alginate Multilayer Microparticles for Vaginal HIV Microbicide Delivery

It is hypothesized that novel thiolated chitosan-coated multilayer microparticles (MPs) with enhanced drug loading are more mucoadhesive than uncoated MPs and safe in vivo for vaginal delivery of topical anti-HIV microbicide. Formulation optimization is achieved through a custom experimental design and the alginate (AG) MPs cores are prepared using the spray drying method. The optimal MPs are then coated with the thiolated chitosan (TCS) using a layer-by-layer method. The morphological analysis, in situ drug payload, in vitro drug release profile, and mucoadhesion potential of the MPs are carried out using scanning electron microscopy, solid-state ³¹P NMR spectroscopy, UV spectroscopy, fluorescence imaging and periodic acid Schiff method, respectively. The cytotoxicity and preclinical safety of MPs are assessed on human vaginal (VK2/E6E7) and endocervical (End1/E6E7) epithelial cell lines and in female C57BL/6 mice, respectively. The results show that the MPs are successfully formulated with an average diameter ranging from 2 to 3 μm with a drug loading of 7-12% w/w. The drug release profile of these MPs primarily follows the Baker-Lonsdale and Korsmeyer-Peppas models. The MPs exhibit high mucoadhesion (20-50 folds) compared to native AGMPs. The multilayer MPs are noncytotoxic. Histological and immunochemical analysis of the mice genital tract shows neither signs of damage nor inflammatory cell infiltrate. These data highlight the potential use of TCS-coated AG-based multilayer MPs templates for the topical vaginal delivery of anti-HIV/AIDS microbicides.

Sulfonate-modified phenylboronic acid-rich nanoparticles as a novel mucoadhesive drug delivery system for vaginal administration of protein therapeutics: improved stability, mucin-dependent release and effective intravaginal placement

Effective interaction between mucoadhesive drug delivery systems and mucin is the basis of effective local placement of drugs to play its therapeutic role after mucosal administration including vaginal use, which especially requires prolonged drug presence for the treatment of gynecological infectious diseases. Our previous report on phenylboronic acid-rich nanoparticles (PBNPs) demonstrated their strong interaction with mucin and mucin-sensitive release profiles of the model protein therapeutics interferon (IFN) in vitro, but their poor stability and obvious tendency to aggregate over time severely limited future application. In this study, sulfonate-modified PBNPs (PBNP-S) were designed as a stable mucoadhesive drug delivery system where the negative charges conferred by sulfonate groups prevented aggregation of nanoparticles and the phenylboronic acid groups ensured effective interaction with mucin over a wide pH range. Results suggested that PBNP-S were of spherical morphology with narrow size distribution (123.5 nm, polydispersity index 0.050), good stability over a wide pH range and 3-month storage and considerable in vitro mucoadhesion capability at vaginal pH as shown by mucin adsorption determination. IFN could be loaded to PBNP-S by physical adsorption with high encapsulation efficiency and released in a mucin-dependent manner in vitro. In vivo near-infrared fluorescent whole animal imaging and quantitative vaginal lavage followed by enzyme-linked immunosorbent assay (ELISA) assay of IFN demonstrated that PBNP-S could stay in the vagina and maintain intravaginal IFN level for much longer time than IFN solution (24 hours vs several hours) without obvious histological irritation to vaginal mucosa after vaginal administration to mice. In summary, good stability, easy loading and controllable release of protein therapeutics, in vitro and in vivo mucoadhesive properties and local safety of PBNP-S suggested it as a promising nanoscale mucoadhesive drug delivery system for vaginal administration of protein therapeutics.

Development of particulate drug formulation against C. parvum: Formulation, characterization and in vivo efficacy

This research aims towards developing an alternative therapy against Cryptosporidium parvum using bioadhesive paromomycin and diloxanide furoate-loaded microspheres. Microspheres were prepared using chitosan and poly(vinyl alcohol) and two types of cyclodextrins (β-CD and DM-β-CD) for the potential use of treating cryptosporidiosis. This pathogen is associated with gastrointestinal illness in humans and animals. Microparticle formulations were characterized in terms of size, surface charge, drug release and morphology. In vivo bioadhesion properties of CHI/PVA microspheres were also evaluated in mice. Finally, the in vivo efficacy of CHI/PVA microspheres against C. parvum was tested in neonatal mouse model. In this work, microspheres prepared by spray-drying showed spherical shape, diameters between 6.67±0.11 and 18.78±0.07μm and positively surface charged. The bioadhesion studies demonstrated that MS remained attached at +16h (post-infection) to the intestinal cells as detected by fluorescence. This finding was crucial taking use of the fact that the parasite multiplication occurs between 16 and 20h post-infection. The efficacy of treatment was determined by calculating the number of oocysts recovered from the intestinal tract of mice after 7days of post-infection. Mice receiving orally administered microspheres with and without drug exhibited significantly lower parasite loads compared with the control mice. Ultrastructural observations by TEM bring to light the uptake of smallest particles by enterocytes associated with conspicuous changes in enterocytic cells. Completely recovery of cell morphology was detected after 24h of first inoculation with MS. CHI/PVA microspheres appear to be a safe and simple system to be used in an anticryptosporidial treatment. The distinctive features of neonatal mice requires further work to determine the suppressive effect of this particulate delivery system on C. parvum attachment in other animal models.

Efficacy of skin and nasal povidone-iodine preparation against mupirocin-resistant methicillin-resistant Staphylococcus aureus and S. aureus within the anterior nares

Mupirocin decolonization of nasal Staphylococcus aureus prior to surgery decreases surgical-site infections; however, treatment requires 5 days, compliance is low, and resistance occurs. In 2010, 3M Company introduced povidone-iodine (PVP-I)-based skin and nasal antiseptic (Skin and Nasal Prep [SNP]). SNP has rapid, broad-spectrum antimicrobial activity. We tested SNP's efficacy using full-thickness tissue (porcine mucosal [PM] and human skin) explant models and human subjects. Prior to or following infection with methicillin-resistant Staphylococcus aureus (MRSA) (mupirocin sensitive and resistant), explants were treated with Betadine ophthalmic preparation (Bet), SNP, or mupirocin (Bactroban nasal ointment [BN]) or left untreated. One hour posttreatment, explants were washed with phosphate-buffered saline (PBS) plus 2% mucin. One, 6, or 12 h later, bacteria were recovered and enumerated. Alternatively, following baseline sampling, human subjects applied two consecutive applications of SNP or saline to their anterior nares. One, 6, and 12 h after application of the preparation (postprep), nasal swabs were obtained, and S. aureus was enumerated. We observed that treatment of infected PM or human skin explants with SNP resulted in >2.0 log10 CFU reduction in MRSA, regardless of mupirocin sensitivity, which was significantly different from the values for BN- and Bet-treated explants and untreated controls 1 h, 6 h, and 12 h after being washed with PBS plus mucin. Swabbing the anterior nares of human subjects with SNP significantly reduced resident S. aureus compared to saline 1, 6, and 12 h postprep. Finally, pretreatment of PM explants with SNP, followed by a mucin rinse prior to infection, completely prevented MRSA infection. We conclude that SNP may be an attractive alternative for reducing the bioburden of anterior nares prior to surgery.

Hybrid nanosystems based on natural polymers as protein carriers for respiratory delivery: Stability and toxicological evaluation

Chitosan/carrageenan/tripolyphosphate nanoparticles were previously presented as holding potential for an application in transmucosal delivery of macromolecules, with tripolyphosphate demonstrating to contribute for both size reduction and stabilisation of the nanoparticles. This work was aimed at evaluating the capacity of the nanoparticles as protein carriers for pulmonary and nasal transmucosal delivery, further assessing their biocompatibility pattern regarding that application. Nanoparticles demonstrated stability in presence of lysozyme, while freeze-drying was shown to preserve their characteristics when glucose or sucrose were used as cryoprotectants. Bovine serum albumin was associated to the nanoparticles, which were successfully microencapsulated by spray-drying to meet the aerodynamic requirements inherent to pulmonary delivery. Finally, a satisfactory biocompatibility profile was demonstrated upon exposure of two respiratory cell lines (Calu-3 and A549 cells) to the carriers. A negligible effect on cell viability along with no alterations on transepithelial electrical resistance and no induction of inflammatory response were observed.

Electricity and colloidal stability: how charge distribution in the tissue can affects wound healing

The role of endogenous electric fields in wound healing is still not fully understood. Electric fields are of fundamental importance in various biological processes, ranging from embryonic development to disease progression, as described by many investigators in the last century. This hypothesis brings together some relevant literature on the importance of electric fields in physiology and pathology, the theory of biologically closed electric circuits, skin battery (a phenomenon that occurs after skin injury and seems to be involved in tissue repair), the relationship between electric charge and interstitial exclusion, and how skin tissues can be regarded as colloidal systems. The importance of electric charges, as established in the early works on the subject and the relevance of zeta potential and colloid stability are also analyzed, and together bring a new light for the physics involved in the wound repair of all the body tissues.

Carboxymethyl-chitosan-tethered lipid vesicles: hybrid nanoblanket for oral delivery of paclitaxel

We describe the development and evaluation of a hybrid lipopolymeric system comprising carboxymethyl chitosan (CMC), covalently tethered to phosphatidylethanolamine units on the surface of lipid nanovesicles, for oral delivery of paclitaxel. The bioploymer is intended to act as a blanket, thereby shielding the drug from harsh gastrointestinal conditions, whereas the lipid nanovesicle ensures high encapsulation efficiency of paclitaxel and its passive targeting to tumor. CMC-tethered nanovesicles (LN-C-PTX) in the size range of 200-300 nm improved the gastrointestinal resistance and mucoadhesion properties as compared with unmodified lipid nanovesicles (LN-PTX). Conjugation of CMC did not compromise the cytotoxic potential of paclitaxel yet facilitated the interaction and uptake of the nanovesicles by murine melanoma (B16F10) cells through an ATP-dependent process. CMC-conjugated nanovesicles, upon oral administration in rats, improved the plasma concentration profile of paclitaxel, with 1.5 fold increase in its bioavailability and 5.5 folds increase in elimination half life in comparison with Taxol. We also found that CMC in addition to providing a gastric resistant coating also imparted stealth character to the nanovesicles, thereby reducing their reticuloendothelial system (RES)-mediated uptake by liver and spleen and bypassing the need for PEGylation. In vivo efficacy in subcutaneous model of B16F10 showed significantly improved tumor growth inhibition and survival with CMC-tethered nanovesicles as compared with unmodified nanovesicles, both administered orally. LN-C-PTX exhibited therapeutic efficacy comparable to Taxol and Abraxane and also showed reduced toxicity and improved survival. Overall, these results suggest the therapeutic potential of CMC tethered nanovesicles as a platform for oral administration of paclitaxel and also unravel the ability of CMC to impart stealth character to the nanoparticles, thereby preventing their RES clearance.

Pullulan-based nanoparticles as carriers for transmucosal protein delivery

Polymeric nanoparticles have revealed very effective in transmucosal delivery of proteins. Polysaccharides are among the most used materials for the production of these carriers, owing to their structural flexibility and propensity to evidence biocompatibility and biodegradability. In parallel, there is a preference for the use of mild methods for their production, in order to prevent protein degradation, ensure lower costs and easier procedures that enable scaling up. In this work we propose the production of pullulan-based nanoparticles by a mild method of polyelectrolyte complexation. As pullulan is a neutral polysaccharide, sulfated and aminated derivatives of the polymer were synthesized to provide pullulan with a charge. These derivatives were then complexed with chitosan and carrageenan, respectively, to produce the nanocarriers. Positively charged nanoparticles of 180-270 nm were obtained, evidencing ability to associate bovine serum albumin, which was selected as model protein. In PBS pH 7.4, pullulan-based nanoparticles were found to have a burst release of 30% of the protein, which maintained up to 24h. Nanoparticle size and zeta potential were preserved upon freeze-drying in the presence of appropriate cryoprotectants. A factorial design was approached to assess the cytotoxicity of raw materials and nanoparticles by the metabolic test MTT. Nanoparticles demonstrated to not cause overt toxicity in a respiratory cell model (Calu-3). Pullulan has, thus, demonstrated to hold potential for the production of nanoparticles with an application in protein delivery.

Cress seed mucilage based buccal mucoadhesive gel of venlafaxine: in vivo, in vitro evaluation

Venlafaxine is a newer antipsychotic drug which shows first pass effect. Cress seed is also called as garden cress or green salad. This study examined the mechanical (gel strength, adhesiveness) and rheological properties of cress seed mucilage based gels that contain different ratios of carbopol 934 P (0.5-1.5%). In addition, diffusion of venlafaxine from gel formulations was evaluated. The selected formulation was further analyzed for pharmacokinetic parameters in rabbits. All formulations exhibited pseudoplastic flow with thixotropy. Formulation F5 showed the C(max) of 24.19 ± 0.72 ng/ml by buccal route of administration and 17.98 ± 1.15 ng/ml by oral route of administration. The bioavailability of F5 by buccal route was 54.44% and that of by oral route was 39.60%. A combination of the cress seed mucilage and carbopol 934 P resulted in a prolonged and higher venlafaxine delivery by buccal route of administration.

Synthesis and in vitro characterization of poly(ethylene glycol)-albumin hydrogel microparticles

High water content hydrogel microparticles based on the cross-linking of albumin with activated poly(ethylene glycol) were synthesized. The influence of different synthesis parameters on the physicochemical characteristics of the microparticles, such as the type of oil and of albumin, and the molecular weight of PEG, was evaluated. The water content of the microparticles ranged from 95 to 98%, increasing with an increase of the molecular weight of PEG. At optimal conditions, microparticles with sizes ranging from 3 to 50 μm were prepared. These microparticles showed a negatively charged surface. They were freely dispersed in PBS buffer and they were stable at 4°C for times varying from 0.5 to 10 months. Initial stirring speed and molecular weight of PEG were the 2 main factors that significantly affected microparticle size. High hydrophilicity, good stability and modulable size make this hydrogel an attractive matrix for protein or cell immobilization for biomedical applications.

Manufacture and characterization of mucoadhesive buccal films

The buccal route of administration has a number of advantages including bypassing the gastrointestinal tract and the hepatic first pass effect. Mucoadhesive films are retentive dosage forms and release drug directly into a biological substrate. Furthermore, films have improved patient compliance due to their small size and reduced thickness, compared for example to lozenges and tablets. The development of mucoadhesive buccal films has increased dramatically over the past decade because it is a promising delivery alternative to various therapeutic classes including peptides, vaccines, and nanoparticles. The "film casting process" involves casting of aqueous solutions and/or organic solvents to yield films suitable for this administration route. Over the last decade, hot-melt extrusion has been explored as an alternative manufacturing process and has yielded promising results. Characterization of critical properties such as the mucoadhesive strength, drug content uniformity, and permeation rate represent the major research areas in the design of buccal films. This review will consider the literature that describes the manufacture and characterization of mucoadhesive buccal films.

Design and ocular tolerance of flurbiprofen loaded ultrasound-engineered NLC

Packaging small drug molecules, such as non-steroidal anti-inflammatory drugs (NSAIDs) into nanoparticulate systems has been reported as a promising approach to improve the drug's bioavailability, biocompatibility and safety profiles. In the last 20 years, lipid nanoparticles (lipid dispersions) entered the nanoparticulate library as novel carrier systems due to their great potential as an alternative to other systems such as polymeric nanoparticles and liposomes for several administration routes. For ocular instillation nanoparticulate carriers are required to have a low mean particle size, with the lowest polydispersity as possible. The purpose of this work was to study the combined influence of 2-level, 4-factor variables on the formulation of flurbiprofen (FB), a lipophilic NSAID, in lipid carriers currently named as nanostructured lipid carriers (NLC). NLC were produced with stearic acid (SA) and castor oil (CO) stabilized by Tween® 80 (non-ionic surfactant) in aqueous dispersion. A 2(4) full factorial design based on 4 independent variables was used to plan the experiments, namely, the percentage of SA with regard to the total lipid, the FB concentration, the stabilizer concentration, and the storage conditions (i.e., storage temperature). The effects of these parameters on the mean particle size, polydispersity index (PI) and zeta potential (ZP) were investigated as dependent variables. The optimization process was achieved and the best formulation corresponded to the NLC formulation composed of 0.05 (wt%) FB, 1.6 (wt%) Tween® 80 and a 50:50 ratio of SA to CO, with an average diameter of 288 nm, PI 0.245 of and ZP of -29 mV. This factorial design study has proven to be a useful tool in optimizing FB-loaded NLC formulations. Stability of the optimized NLC was predicted using a TurbiScanLab® and the ocular tolerance was assessed in vitro and in vivo by the Eytex® and Draize test, respectively. The developed systems were shown physico-chemically stable with high tolerance for eye instillation.

Mucoadhesive drug delivery systems

Drug actions can be improved by developing new drug delivery systems, such as the mucoadhesive system. These systems remain in close contact with the absorption tissue, the mucous membrane, releasing the drug at the action site leading to a bioavailability increase and both local and systemic effects. Mucoadhesion is currently explained by six theories: electronic, adsorption, wettability, diffusion, fracture and mechanical. Several in vitro and in vivo methodologies are proposed for studying its mechanisms. However, mucoadhesion is not yet well understood. The aim of this study was to review the mechanisms and theories involved in mucoadhesion, as well as to describe the most-used methodologies and polymers in mucoadhesive drug delivery systems.

Mucoadhesive bilayered patches for administration of sumatriptan succinate

The purpose of this study was to develop and optimize formulations of mucoadhesive bilayered buccal patches of sumatriptan succinate using chitosan as the base matrix. The patches were prepared by the solvent casting method. Gelatin and polyvinyl pyrrolidone (PVP) K30 were incorporated into the patches, to improve the film properties of the patches. The patches were found to be smooth in appearance, uniform in thickness, weight, and drug content; showed good mucoadhesive strength; and good folding endurance. A 3(2) full factorial design was employed to study the effect of independent variables viz. levels of chitosan and PVP K30, which significantly influenced characteristics like swelling index, in-vitro mucoadhesive strength, in vitro drug release, and in-vitro residence time. Different penetration enhancers were tried to improve the permeation of sumatriptan succinate through buccal mucosa. Formulation containing 3% dimethyl sulfoxide showed good permeation of sumatriptan succinate through mucosa. Histopathological studies revealed no buccal mucosal damage. It can be concluded that buccal route can be one of the alternatives available for administration of sumatriptan succinate.

In vitro and ex vivo intestinal tissue models to measure mucoadhesion of poly (methacrylate) and N-trimethylated chitosan polymers

PURPOSE

The adhesion of a range of polymers based on poly(2-(dimethylamino-ethyl) methacrylate (pDMAEMA) was assessed using human mucus-secreting and non mucus-secreting intestinal cell monolayers, HT29-MTX-E12 (E12) and HT29 monolayers, as well as excised non-everted intestinal sacs from rats. Differentiation of mucoadhesion from bioadhesion was achieved by pre-treatment with the mucolytic agent, N-acetyl cysteine (NAC). Adherence of pDMAEMA polymers was compared to that obtained with the mucoadhesive, N-trimethylated chitosan (TMC).

METHODS

The quantity of adherent coumarin 343-conjugated polymers to HT29, E12, and intestinal sacs was measured by fluorescence. Confocal laser scanning microscopy (CLSM), light microscopy, and fluorescent microscopy were used to provide direct evidence. Measurements of transepithelial electrical resistance (TEER), permeability to FITC-dextran 4000 (FD-4), and the release of lactate dehydrogenase (LDH) were used to assess potential cytotoxicity of polymers.

RESULTS

Adherence of unquaternized and of 10%, 24%, and 32% methyl iodide-quaternized pDMAEMA polymers was measured in E12, HT29, and sacs. All pDMAEMA polymers showed significantly higher levels of adhesion to mucus (mucoadhesion) than to epithelium (bioadhesion). Colocalization of pDMAEMA with mucus was confirmed in E12 by microscopy. TMC showed equally high levels of mucoadhesion as unquaternized and 24% quaternized pDMAEMA, but displayed higher levels of bioadhesion. pDMAEMA-based polymers demonstrated lower levels of adherence to E12 and rat sacs in the presence of NAC, whereas adherence of TMC was unchanged. pDMAEMA significantly decreased the permeability of FD-4 across E12 monolayers and sacs and was less cytotoxic in E12 than in HT29. In contrast, TMC increased the permeability of FD-4 across E12 and sacs and was less cytotoxic in E12 than in HT29.

CONCLUSIONS

Human mucus-producing E12 monolayers can be used to assess polymer mucoadhesion and give similar data to isolated rat intestinal sacs. pDMAEMA displayed similar levels of mucoadhesion and lower levels of bioadhesion than a chitosan derivative and it was not cytotoxic. pDMAEMA decreased FD-4 flux in the presence of mucus, whereas TMC increased it. The combination of mucus and methacrylate polymers appears to increase barrier function of the apical membrane.

Pharmaceutical applications of mucoadhesion for the non-oral routes

The adhesion of pharmaceutical formulations to the mucosal tissue offers the possibility of creating an intimate and prolonged contact at the site of administration. This prolonged residence time can result in enhanced absorption and, in combination with a controlled release of the drug, also improved patient compliance by reducing the frequency of administration. During the almost 30 years over which mucoadhesion has been studied, a considerable amount of knowledge has been gained, and much has been learned about the different mechanisms occurring at the formulation-mucus interface and the properties that affect these mechanisms. The in-vivo performance of a dosage form not only depends on the mechanisms occurring at the interface, but also on the properties of the total mucoadhesive complex: the dosage form, the mucosa and the interface between them. A wide variety of methods are used for studying mucoadhesion; some rather similar to the in-vivo situation and some mimicking the interface alone. In this review, the mucus surface, the methods used for the study of mucoadhesion, the different mechanisms involved in mucoadhesion and theories underpinning them have been described. The complexity of mucoadhesion when trying to systemize the subject will also be discussed. The last part of the review describes the buccal, nasal, ocular, vaginal and rectal routes and provides examples of what can be achieved in-vivo when using mucoadhesive formulations.

Determination of main low molecular weight antioxidants in urinary bladder wall using HPLC with electrochemical detector

The aim of the present work was to develop validated HPLC method using electrochemical detector for simultaneous detection of low molecular weight antioxidants (LMWA) in urinary bladder. Furthermore, the method was applied to study the distribution of LMWA in urinary bladder wall. The ascorbic acid (AA), glutathione in reduced (GSH) and oxidized (GSSG) form and uric acid (UA) were resolved by isocratic elution from C18 reversed-phase column. The bladder tissue sample preparation involved extraction with meta-phosphoric acid solution for LMWA stabilization. The AA, GSH and UA tissue peak was identified by different approaches. The obtained method validation parameters were in acceptable range: intra-day precision (<4.4%), intra-day accuracy (<8.4%), inter-day precision (<9.4%) and inter-day accuracy (<15.6%). Additionally, the method provided good linearity (r2>0.99) and recoveries (98.9-112.6%). The distribution of LMWA in urinary bladder was determined by measuring their concentration in bladder wall layers: urothelium, lamina propria, muscularis and serosa. The validated method was able to quantify the reduced form of all three LMWA in all four bladder wall layers. The LMWA concentrations were decreasing from urothelium to serosa except of UA. The developed HPLC method with electrochemical detection of LMWA is simple, fast and can be used for simultaneous quantification of LMWA in tissues, which contain low concentrations of antioxidants.