Mucoadhesive membranes were proposed in this study as drug delivery system for betamethasone-17-valerate (BMV) in the treatment of recurrent aphthous stomatitis (RAS). The membranes were obtained by using the polymers chitosan (CHI) in both presence and absence of polyvinilpyrrolidone (PVP), following the solvent evaporation method.
Carbohydrate Polymers 190 (2018) 339–345 Contents lists available at ScienceDirect Carbohydrate Polymers journal homepage: www.elsevier.com/locate/carbpol Chitosan/pvp-based mucoadhesive membranes as a promising delivery system of betamethasone-17-valerate for aphthous stomatitis T R.H Sizílioa, J.G Galvãoa, G.G.G Trindadea, L.T.S Pinaa, L.N Andradeb, J.K.M.C Gonsalvesa, ⁎ A.A.M Liraa, M.V Chaudc, T.F.R Alvesc, M.L.P.M Arguelhod, R.S Nunesa, a Pharmacy Department, Federal University of Sergipe, São Cristóvão, SE, Brazil Instituto de Tecnologia e Pesquisa (ITP), Tiradentes University, Aracaju, SE, Brazil c Laboratory of Biomaterial and Nanotechnology, University of Sorocaba, Sorocaba, SP, Brazil d Chemistry Department, Federal University of Sergipe, São Cristóvão, SE, Brazil b A R T I C LE I N FO A B S T R A C T Keywords: Betamethasone-17-valerate Aphthous stomatitis Chitosan Polymeric blends PVP Mucoadhesive membranes were proposed in this study as drug delivery system for betamethasone-17-valerate (BMV) in the treatment of recurrent aphthous stomatitis (RAS) The membranes were obtained by using the polymers chitosan (CHI) in both presence and absence of polyvinilpyrrolidone (PVP), following the solvent evaporation method The presence of PVP in the membranes causes significant modifications in its thermal properties Changes in the thermal events at 114 and 193 °C (related to BMV melting point), and losses in mass (39.38 and 30.68% for CH:PVP and CH:PVP-B, respectively), suggests the incorporation of BMV in these membranes However, the morphological aspects of the membranes not change after adding PVP and BMV PVP causes changes in swelling ratios (> 80%) of the membranes, and it is suggested that the reorganization of the polymer mesh was highlighted by the chemical interactions between the polymers leading to different percentages of BMV released ∼40% and ∼80% from CH-B and CH:PVP-B BMV release profile follows Korsmeyer and Peppas model (n > 0.89) which suggests that the diffusion of the drug in the swollen matrix is driven by polymer relaxation In addition, the membranes containing PVP (higher swelling ability) present high rates of tensile strength, and therefore, higher mucoadhesion Moreover, given the results presented, the developed mucoadhesive membranes are a promising system to deliver BMV for the treatment of RAS Introduction Recurrent aphthous stomatitis (RAS) is an oral disease that affects one quarter of the world’s population, and it is common in the first stage of human development (Kürklü-Gürleyen, Ưğüt-Erişen, Çakır, Uysal, & Ak, 2016; Scully, 2006) This disease is characterized by oval or round shaped lacerations in the oral mucosa and lips, and pain ranging from mild to moderate in the first 24 h Moreover, RAS are small ulcers (2–10 mm of diameter) presenting well-defined edges and white-yellowish color Besides that, RAS affects the non-keratinazed mucosa, and may occur isolated or associated with other diseases The mucous tissue is able to restructure spontaneously in 7–14 days after the lesion first appears (Kürklü-Gürleyen et al., 2016; Scully, 2006; Tappuni, Kovacevic, Shirlaw, & Challacombe, 2013) The mucosa lacerations may lead to impairment of upper digestive tract functions, since these ulcers cause difficulties in speaking and swallowing food, liquids and saliva (Kürklü-Gürleyen et al., 2016; Tappuni et al., 2013) The treatment of RAS is focused on accelerating the healing, as well as, easing the pain In general, corticoids are the first choice in the treatment of oral autoimmune diseases According to Carrozzo and Gandolfo (cited by (Rogulj, Brkic, Alajbeg, Džanić, & Alajbeg, 2014)), steroidal anti-inflammatory drugs such as betamethasone-17-valerate (BMV) are indicated to treat oral mucosa lesions, as they act reducing inflammation and pain without leading to undesirable effects in short term However, the prolonged use of these drugs may cause adverse effects that would result in non-adherence to treatment Thus, polymeric systems have been investigated as an interesting viable option to transport steroidal anti-inflammatory drugs, since they can deliver a limited and continuous amount of drug, and can contribute to the tissue healing process at the same time (Rogulj et al., 2014) Mucoadhesive polymeric systems play a crucial role in the RAS therapy as they are a suitable vehicle to deliver drugs as well as they can cover the oral lesion for a long-term preventing the worsening of the lesion and proliferation of bacteria (Kürklü-Gürleyen et al., 2016) ⁎ Corresponding author at: Pharmacy Department, Federal University of Sergipe, Av Marechal Rondon, s/n, Prof José Aloísio de Campos City University, 49100-000, São Cristóvão, Sergipe, Brazil E-mail address: rogeria.ufs@hotmail.com (R.S Nunes) https://doi.org/10.1016/j.carbpol.2018.02.079 Received 28 November 2017; Received in revised form 17 January 2018; Accepted 23 February 2018 Available online 06 March 2018 0144-8617/ © 2018 Elsevier Ltd All rights reserved Carbohydrate Polymers 190 (2018) 339–345 R.H Sizílio et al Among polymers, chitosan (CHI) has been widely investigated for biomedical application and drug delivery system CHI is a natural polysaccharide constituted of β-(1–4)-linked Dglucosamine and N-acetyl-D-glucosamine units and presents functional groups such as amine and hydroxyl that have influence over its biological properties, especially in the cellular adherence and interaction with mucosa proteins, particularly on α-2,3 and α-2,6 sialic acids In addition, CHI is considered non-toxic, biocompatible, mucoadhesive, aids tissue healing, and is able to interact with human cells (Cai et al., 2009; Liu et al., 2014; Swetha et al., 2010) However, it has been reported that one of the major drawbacks of CHI-based hydrogel membranes is their low mechanical stability because of their high water content (especially in acidic solutions) and relatively loose three dimensional (3D) network formed by linear polyssacaride molecules (Ostrowska-Czubenko, Pierõg, & Gierszewska-Druzyńska, 2013) According to Gierszewska & Ostrowska-Czubenko (2016), the modification of chitosan by crosslinking is an effective strategy to improve its mechanical resistance Therefore, in this work, a crosslinking agent (TPP) was used for all membranes The combination of CHI and other polymers (mainly hydrophilic) can also be used to improve its functional properties (e.g mucoadhesive) The polyvinylpyrrolidone (PVP) is a synthetic copolymer, biocompatible and non-toxic (Elsabee & Abdou, 2013) This polymer has been applied in formulations for controlled drug delivery, and wound dressings by pharmaceutical and biomedical industries, respectively (Archana, Singh, Dutta, & Dutta, 2013; Elsabee & Abdou, 2013) The interaction between PVP and CHI occurs through the formation of hydrogen bonds between the pyrrolidine rings of PVP and; amino and hydroxyl groups of CHI, which can present high material miscibility with improved properties (Li, Zivanovic, Davidson, & Kit, 2010) Khoo, Frantzich, Rosinski, Sjöström, and Hoogstraate (2003) evaluated the miscibility between CHI and hydrophilic polymers such as PVP observing improved mechanical/physical and thermal properties when PVP was present Thus, the aim of this study is to develop BMV loaded CH-PVP mucoadhesive membranes as a potential drug delivery system for RAS treatment Furthermore, this work evaluates the influence of PVP in the membranes regarding thermal properties, swelling capacity, drug release profile and mucoadhesive ability Table CH-PVP blends and CH films composition SAMPLES CHI (mL) PVP (mL) PPG (mL) BMV (mg) CH:PVP CH:PVP-B CH CH-B 60 60 90 90 30 30 – – 10 10 10 10 – – solution, poured into Petri dishes and maintained overnight in the oven at 50 ± °C, to allow the solvent evaporation Subsequently, the membranes were immersed in a 5% TPP solution (w/v, pH adjusted to 5.0), and kept at °C for h Afterwards, the membranes were thoroughly washed several times with distilled water When completely dried, the membranes were kept in a desiccator to avoid humidity Following a similar procedure, membranes without PVP were prepared, in order to evaluate its influence in membrane properties, as detailed in Table For the loaded BMV membranes, the addition of BMV (1 mg mL−1), which was solubilized in PPG (10% of the membrane composition as shown in Table 1), occurred soon after hydrogel preparation, by stirring continuously for 24 h The other steps followed the same procedures, as the inert membrane, previously described 2.2.2 Thermal analysis DSC curves were obtained using a DSC-TA Instruments (New Castle, USA) under nitrogen dynamic atmosphere (20 mL min−1), heating rate of 10 °C min−1, in the temperature range 25–300 °C About mg of sample was sealed tightly in aluminum crucibles DSC cell was calibrated with indium (m.p 156.6 °C; ΔHmelt = 28.54 J g−1) and zinc (m.p 419.6 °C) TG curves were carried out using a thermobalance, model TGA-50 Shimadzu (Kyoto, Japan), in the temperature range of 25–800 °C, using alumina crucibles with approximately mg of samples under dynamic nitrogen atmosphere (50 mL min−1) and heating rate of 10 °C min−1 TG/DTG was calibrated using a CaC2O4·H2O standard in conformity to ASTM 2.2.3 X-ray diffaction X-ray diffraction of CHI, TPP, PVP, BMV and membranes (CH and CH-PVP) with or without the presence of BMV were performed in a Rigaku Diffractometer, with CuKα (1.5406 Å) in the range of 3° < 2θ < 40° using 40 kV of voltage and 30 mA of current The measurements were carried out using steps at 0.02 and speed of 2°/min Material and methods 2.1 Material 2.2.4 Scanning electron microscopy (SEM) The morphology of the membranes was analyzed by scanning electron microscope (model JCM-5700, Tokyo, Japan) with LV acceleration voltage of 20 kV, and a magnitude of 500× and 1000× The samples were placed on copper strips, attached to a blade, and then covered with gold film SEM analysis was performed in the Northeast Center for Strategic Tecnologies (CETENE, Pernambuco, Brazil) Lower molecular weight chitosan (degree of deacetylation 95.25% obtained experimentally) was acquired from Sigma-Aldrich® (St Louis, USA), betamethasone-17-valerate (BMV) was purchased from Henrifarma® (São Paulo, Brazil), and polyvinylpyrrolidone (PVP), sodium tripolyphosphate (TPP) from SYNTH® (São Paulo, Brazil) Also were used monobasic potassium phosphate USP-standard (KH2PO4) (SYNTH®, São Paulo, Brazil), sodium hydroxide (NaOH) analytical grade from SYNTH® (São Paulo, Brazil), ethanol analytical grade (NEON®, São Paulo, Brazil), and propylene glycol (PPG) (VETEC®, Rio de Janeiro, Brazil) Water used in this study was obtained from the Milli-Q® purification water system (Millipore, Darmstadt, Germany) 2.2.5 Thickness and swelling studies The thickness of the membranes were measured in five different points of each sample using a manual micrometer Starrett® n° 436.2, 0–25 mm Swelling degree was evaluated through (%) hydration determination The membranes of cm2 were weighed and immersed in phosphate buffer pH 7.4 at 37 ± °C After immersion, the membranes were taken out from the medium, excess fluid was removed with filter paper and then the membranes were weighed at predetermined times (10, 30, 60, 90, 120 min) All samples were performed in triplicate Swelling ratio was calculated based on the mass gain in relation to dry membrane, according to Eq (1) The results were expressed by the average percentage and its standard deviation In the equation, the swollen membrane weight is represented by Pf and the dry membrane 2.2 Methods 2.2.1 Preparation of CH membranes The membranes were obtained by using the casting/solvent evaporation technique (Liang, Liu, Huang, & Yam, 2009; Srinivasa, Ramesh, Kumar, & Tharanathan, 2004) Firstly, CHI (1.5% w/v) was solubilized in a 2% (v/v) acetic acid solution, and kept under stirring for 24 h For the membranes containing PVP, PVP solution (15%, w/v) was added to the chitosan hydrogel, as described in Table The obtained hydrogel had the pH adjusted to 5.0 using NaOH mol L−1 340 Carbohydrate Polymers 190 (2018) 339–345 R.H Sizílio et al by Pi One-way ANOVA followed by the Tukey’s post-test was carried out using the statistical program Graph Pad Prism v 5.0 DEMO %W = 100 + (Pf − Pi)/(Pf) (1) 2.2.6 In vitro release studies In vitro release studies of BMV were conducted using suitable apparatus connected to thermostatically-controlled water bath at 37 ± 0.5 °C Release medium was composed by phosphate buffer pH 7.4 and ethanol (7:3) which was kept under constant stirring (600 rpm) The membranes were attached in proper holders and immersed in the release medium that was appropriately sealed At time intervals of 0–8 h, mL of release medium was taken out and immediately replaced by new medium solution, at each sample, in order to maintain sink conditions Drug released amount was measured by spectrophotometry (UV/VIS FEMTO®, 800 XI, São Paulo, Brazil) at the wavelength of 240 nm (Rodrigues et al., 2009) In addition, BMV release data was evaluated using kinetic models such as zero order, first order, Higuchi, Korsmeyer & Peppas and Weibull by KinetDS Copyright (C) 2010 Aleksander Mendyk software Fig TG/DTG obtained at 10 °C min−1 under dynamic nitrogen atmosphere (50 mL min−1) for the blends (CH:PVP, CH:PVP-B) and membranes (CH, CH-B) change significantly in relation to the inert membranes (Fig 1) For the CH-B, the first loss in mass was lower (1°Δm = 17% and 14% − DTGpeak = 53 °C; CH and CH-B, respectively) which indicates that some water molecules were displaced in order to accommodate the drug The second event also occurred in the same range and identical DTGpeak with higher loss in mass for CH, indicating that BMV demonstrated a better thermal stability for these temperature ranges (2°Δm = 39% and 30% − DTGpeak = 231 °C; CH and CH-B, respectively) On the other hand, the presence of the drug was enough to increase in 100% the last loss in mass step (11–32%) The higher the amount of organic material, higher the loss in mass of carbonaceous compounds that occurs exactly in this range of temperature For the membranes containing PVP was observed a strong possibility of favorable interaction between BMV and polymeric matrix due to the disappearance of the last loss in mass in the membrane containing BMV The membranes (CH:PVP-B, CH-B, CH:PVP and CH) also were evaluated by DSC (Fig 2(a)) The inert membranes (CH:PVP and CH) exhibited endothermic events associated to water loss and hydroxyl groups of the chitosan and PPG at 108 and 125 °C for CH and CH:PVP, respectively (Abdelrazek et al., 2010; Li et al., 2010) CH membranes presented lower temperature of this first event than CH:PVP membranes, probably due to the interaction between hydroxyl groups of chitosan and carbonyl group of PVP suggesting the blend formation Moreover, CH:PVP showed other endothermic events at 188 and 319 °C, absent in CH, which also indicates an interaction between CHI and PVP (Fig 2(b)) Marsano, Vicini, Skopińska, Wisniewski, and Sionkowska (2004) reported that the pyrrolidone rings in PVP contain a proton accepting carbonyl moiety, while chitosan presents hydroxyl and amino groups as side groups and, therefore, a hydrogen-bonding interaction may take place between these two chemical moieties They also stated that the hydrogen bonds between two macromolecules compete with the formation of hydrogen bonds between molecules of the same polymer Another type of interaction that may occurs is associated with the crosslinking of chitosan with TPP The electrostatic interaction between CHI and TPP occurs at molecular level with release of water molecules and displacement of the main thermal events of the polymer (Hashad, Ishak, Fahmy, Mansour, & Geneidi, 2016) BMV interfered in thermal profile of the blend The membranes containing BMV exhibited an intensity reduction of the DSC peaks The first DSC event of the membranes shift to lower temperatures may be associated with the presence of BMV in polymer matrix, since BMV contributed with hydroxyl groups, indicating the incorporation of BMV in the membranes In absence of PVP (CH-B membrane), the DSC profile 2.2.7 Mucoadhesive property evaluation The mucoadhesive property evaluation was determined by the relation of load (N) as a function of time (s) using texture analyzer (Stable Micro Systems - TA-XT Plus Analyzer Surrey, United Kingdom) The texturometer was, previously, calibrated with kg load cell and equipped with 10 mm diameter analytical probe To determine the mucoadhesive property, a compact disc of the mucin from porcine stomach was used (150 mg and 0.2 mm of thickness) The discs were fixed with double-sided cohesive tape on the lower base of the test piece (n.15347) The samples were transferred to mucoadhesion test apparatus (n.15467) Mucin discs were previously hydrated with ultrapure water During the whole experiment, the temperature was kept constant at 37 °C The method executed in this test was adapted from (Fransén, Björk, & Edsman, 2008), and performed in speed compression mode at 0.5 mm s−1, under a force of g After 60 s of contact, the test piece was moved in opposite direction at 1.0 mm s−1 of speed The maximum force required to separate the mucin disc on the sample surface was detected and analyzed by Texture Expoente Lite software The measurements were performed in triplicate One-way ANOVA followed by the Tukey’s post-test was carried out using the statistical program Graph Pad Prism v 5.0 DEMO Results and discussion Thermal analysis is an important technique for the evaluation of polymeric membranes regarding mass variations and thermal events related to the blend formation (Abdelrazek, Elashmawi, & Labeeb, 2010; Rafique, Zia, Zuber, Tabasum, & Rheman, 2016) TG/DTG curves of the membranes are shown in Fig All samples presents different losses in mass possibly related to chemical changes that occurred after the membrane formation PVP as blend forming provides changes in the thermal profile of the membranes The first thermal event regarding water loss (Nieto-Suárez, López-Quintela, & Lazzari, 2016) was Δm = 17% and 12% (DTGpeak = 53 °C), with and without PVP respectively Thermal decomposition and release of carbonaceous material are higher in the membrane containing PVP (Δm = 23%, DTGpeak = 436 °C, and Δm = 4%, DTGpeak = 534 °C, against Δm = 11%, above 343 °C of the membrane without PVP) After the incorporation of PVP, the thermal stability of the membranes changed exhibiting new losses in mass Similar results were found by Bigucci et al (2015) in which blends composed of chitosan and hyaluronic acid presented different losses in mass compared with pure chitosan The thermal profile of the membranes containing BMV did not 341 Carbohydrate Polymers 190 (2018) 339–345 R.H Sizílio et al Fig (a) DSC curves for CH:PVP, CH, CH:PVP-B and CH-B; (b) DSC curves for CHI, TPP, PVP and BMV; obtained with a heating rate of 10 °C min−1 and dynamic atmosphere of nitrogen (20 mL min−1) Croisier & Jérôme, 2013; Gonsalves, Ferro, Barreto, Nunes, & Valerio, 2016; Lewandowska, 2011) TPP presented several well-defined peaks, which are related to its crystalline nature The XRD pattern of BMV showed main peaks in 14°, 17°, 28° and a wide peak with maximum intensity between 11° and 12° Observing the membrane’s diffraction patterns, their similarity was evident and both showed diffraction peaks (two low intensity ones at 18 and 25°, and two high intensity ones at 14 and 16) The pattern shift when comparing to the isolated components suggests a conformational change when the membrane is formed Conformational changes were also observed by Abugoch, Tapia, Villamán, Yazdani-Pedram, and DíazDosque (2011) and by Lewandowska (2011), when they evaluated chitosan/quinoa protein membranes, and chitosan acetate/PVP, respectively The XRD peaks related to the BMV were not observed in the membranes containing the drug (CH-B and CH-PVP-B) According to Subha, Mallikarjuna, Pallavi, Rao, and Rao (2015), this indicates that the drug is dispersed at the molecular level in the membrane and therefore, no drug peaks could be observed SEM analysis of the membranes is shown in Fig It is possible to observe that the membranes present a smooth, compact and homogeneous surface The absence of defects in the CH and CH-B indicates that PPG contributed to CHI dispersion capacity during solvent casting process showing a good compatibility between them Usually, plasticizers acts on the polymer compatibility with CHI during membrane formation (Van Den Broek, Knoop, Kappen, & Boeriu, 2015) is similar to the raw materials with slightly shifts No BMV melting point is observed in the membranes containing PVP suggesting a good miscibility of BMV in the blend Fig 2(b) shows the DSC curves of chitosan, TPP, PVP and BMV Chitosan exhibited: i an endothermic event at 97 °C, which corresponds to water loss; ii an endothermic event at 277 °C, related to decomposition of amino groups of chitosan (Abdelrazek et al., 2010; Santos, Soares, Dockal, Campana Filho, & Cavalheiro, 2003); iii a third event, exothermic, close to 300 °C TPP presents one main endothermic peak at 114 °C related to melting PVP exhibited an endothermic event at 113 °C regarding glass transition Kadota, Otsu, Fujimori, Sato, and Tozuka (2016) and Knopp et al (2015) reported PVP glass transition at 168 and 160 °C respectively This difference in glass transition temperature may be associated to changes in molecular weight, purity and crystallinity degree of PVP obtained from different origins (Homayouni, Sadeghi, Varshosaz, Garekani, & Nokhodchi, 2014; Knopp et al., 2015) BMV is considered a crystalline drug, presenting melting point at 195 °C There are three polymorphs of BMV commercially available, and they differ in crystal lattice due to preparation process and crystallization It was observed that the BMV polymorph studied in this work is the polymorph II (Näther, Jess, Seyfarth, Bärwinkel, & Senker, 2015) The XRD profile of the polymers, PVP and CHI are shown in Fig It is possible to observe two main wide assymetric peaks at 11° and 21°; 12° and 20°, respectively, which are indicative of semi-crystalline materials, as previously described in the literature (Azevedo et al., 2011; Fig X-ray diffraction pattern for (a) PVP, CHI, TPP and BMV; (b) CH, CH-B, CH:PVP and CH:PVP-B membranes 342 Carbohydrate Polymers 190 (2018) 339–345 R.H Sizílio et al Fig Photomicrographs of inert and drug loaded membranes through scanning electron microscopy The blend formation between CHI and PVP also was observed by SEM, in which minor imperfections with circular shape were detected These imperfections may be related to casting process or an incompatibility between the polymers Generally, polymeric blends surfaces are smooth and homogeneous with a certain degree of immiscibility Yin, Luo, Chen, and Khutoryanskiy (2006) reported that CHI/cellulose derivatives blends presented smooth surface, but in crosssection view they showed irregularities probably related to polymer immiscibility Nevertheless, DSC analysis did not demonstrate any polymer immiscibility suggesting that the imperfections occurred due to solvent casting process No changes were detected after drug incorporation (CH:PVP-B and CH-B) No clusters were observed, suggesting BMV incorporation in the polymeric matrix These results are in agreement with previous characterizations The thickness of the inert chitosan membrane containing PVP (48.66 ± 7.57 μm) was slightly thicker than the membrane without PVP (39.33 ± 1.15 μm) On the other hand, almost no changes in thickness were observed after BMV incorporation Swelling studies can be very useful to understand the drug delivery mechanism, since the higher release can be attributed to the higher extent of water uptake, resulting in increased wetting and penetration of water into the film matrices, and hence, increased diffusion of the drug (Koland, Charyulu, Vijayanarayana, & Prabhu, 2011) Several parameters can affect the swelling ratio, hydrophilicity, stiffness and pore structure of a matrix The higher degree of swelling is, higher the surface area/volume ratio The hydrophilic nature of chitosan material may be a major factor that influences the extent of swelling of these matrices (Archana et al., 2013) Fig presents the swelling profile of the CH membranes with PVP (CH:PVP-B and CH: PVP) or without (CH-B and CH) It is possible to observe that the presence of PVP in the membrane allowed higher percentages of swelling (> 80%) Koland et al (2011) found similar Fig Swelling profile of the CH:PVP, CH:PVP-B, CH and CH-B performed at 37 °C using phosphate buffer (pH = 7.4) as media results where the presence of PVP, a hydrophilic polymer, increased the extent of swelling, and the maximum swelling was obtained in the formulation that contained higher amounts of PVP On the other hand, the presence of the drug in the membranes slightly decreased their swelling, which probably occurred due to the poor solubility of BMV in water (Lucangioli et al., 2003), influencing the extent of swelling of chitosan In addition, as previously shown in the DSC analysis, the presence of BMV in the membranes resulted in displacement of water molecules, which may also reduce the chitosan swelling ability Fig shows the in vitro release of betamethasone-17-valerate for chitosan films with (CH:PVP-B) or without PVP (CH-B), and in both formulations the drug release occurred very quickly, and plateaus were reached within 30 and h, respectively (Khoo et al., 2003) Thus, since the BMV needs to reach the oral mucosa quickly, the developed membranes were appropriate As expected, the drug release followed the trends for swelling ability; the chitosan films with PVP presented the final total drug release of ∼80%, greater than that chitosan films without PVP ∼40% 343 Carbohydrate Polymers 190 (2018) 339–345 R.H Sizílio et al organization, which promoted higher adhesivity These results suggest that there is two mechanism of mucoadhesion acting mutually One by electrostatic force between CHI- sialic acids and other by chain interpenetration of the PVP into the mucin layer In this case, the first one is more important than second In addition, the presence of BMV in the membranes causes decrease in mucoadhesion, and probably occurred due to the rearrangement of polymeric chain to accommodate the drug As previously observed in DSC, the incorporation of BMV resulted in displacement of water molecules in order to its incorporation This displacement of water molecules led to a reduction in swelling ability (as previously shown in swelling studies) and consequently in the decrease of mucoadhesion Conclusion Fig In vitro release profiles of betamethasone-17-valerate from CH and CH:PVP membranes This study proposed the preparation of mucoadhesive membranes constituted of CHI and PVP as a potential drug delivery system for BMV in the RAS treatment The presence of PVP in the membranes possibly provides chemical interactions with CHI which improves the thermal stability as observed in thermal analysis Moreover, PVP increased the swelling ratio of the membranes, and therefore improved the BMV release rate (∼80% in less than h) and promoted higher mucoadhesion On the other hand, BMV modifies the swelling ratio and the mucoadhesion, probably due to the displacement of water molecules originally found in the membranes by drug molecules Thus, the results of this study suggest that the developed system is appropriate to deliver BMV aiming the RAS treatment In addition, these systems may be further evaluated using animal model Table Mucoadhesive properties of CH, CH-B, CH:PVP, CH:PVP-B membranes Sample Area to Positive Peak (N s) Peak Positive Force CH CH-B CH:PVP CH:PVP-B −1.167 −2.590 −3.783 −2.461 0.326 0.186 0.479 0.249 ± ± ± ± 1.374 0.039 0.523 0.069 ± ± ± ± 0.048 0.021 0.050 0.039 The betamethasone 17-valerate release profiles were fitted to the Korsmeyer and Peppas model (Ritger & Peppas, 1987) to investigate whether the release of the drug was related to both the polymer relaxation, in contact with the solvent, and/or the diffusion of the active, through the hydrated matrix This phenomenon has been reported to occur in swellable polymers, such as chitosan (Talón, Trifkovic, Vargas, Chiralt, & González-Martínez, 2017) The generalized expression of the Korsmeyer and Peppas is described in Eq (2) Mt / M ∞ = kt n Acknowledgments The authors are grateful to CAPES (Coordenaỗóo de Aperfeiỗoamento de Pessoal de Nớvel Superior) and FAPITEC/SE (Fundaỗóo de Apoio Pesquisa e Inovaỗóo Tecnolúgica Estado de Sergipe) for financial support CETENE-PE (Centro de Tecnologia Nordeste, Pernambuco, Brazil), Departments of Physics and Chemistry of the Federal University of Sergipe (UFS) for carrying out the tests Rosangela H Sizílio is also grateful to CAPES for the Masters grant (2) where Mt/M∞ corresponds to the fraction of the drug released at time t, k is the rate constant of the membrane, related to the diffusion process, and n is the diffusional exponent that is related to the mechanisms involved in the release process Thus, for thin films a n value of 0.5 means that the release obeys the Fickian diffusion model, whereas if the n value is higher than 0.5, known as anomalous transport, the diffusion and the polymer relaxation are coupled (Serra, Doménech, & Peppas, 2009; Siepmann & Peppas, 2012) In this work the n value found was higher than 0.5, which corresponds to anomalous transport According to de Souza, Goebel, and Andreazza (2013), the anomalous transport suggests that the solvent diffusion rate and polymer relaxation process occur in the same order of magnitude, in other words, the transport consists in both drug diffusion in the hydrated matrix and polymer relaxation Among several factors, the swelling ability is closely related to the bioadhesive properties of polymers The ability of certain polymers in absorbing fluids, especially from human body, it becomes possible their application in mucoadhesive formulations The swelling ability is essential to enable the adherence of the formulation in the mucosa (Carvalho, Chorilli, & Gremião, 2014) In order to adhere to the mucosa, the polymers should absorb a certain amount of fluid until the polymeric structure reach the top of remodeling which is succeed by permeation of mucin and other proteins Only polymers with dissociated functional groups can interact electrostatically with mucin Table shows that the blends (CH:PVP and CH:PVP-B), which presented higher rates of water absorption (Fig 5), also demonstrates higher tensile strength rate, in other words, higher muco(bio)adhesivity As related previously, the chemical interaction between the functional groups of CHI and PVP provided a better structural Appendix A Supplementary data 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F., Yoshida, M I., Saliba, J B., Junior, A S C., & Faraco, A A G (2009) In vitro release and characterization of chitosan films as dexamethasone carrier International Journal of Pharmaceutics,... Thermal analysis is an important technique for the evaluation of polymeric membranes regarding mass variations and thermal events related to the blend formation (Abdelrazek, Elashmawi, & Labeeb,... 1016/j.ijpharm.2008.09.047 Rogulj, A A., Brkic, D., Alajbeg, I., Džanić, E., & Alajbeg, I (2014) Nonaromatic naphthalan for the treatment of oral mucosal diseases Acta Dermatovenerologica Croatica, 22(4),