Organic cocoa extract -loaded surfactant-based systems intended to skin bioadhesion

ABSTRACT This study was to develop, characterize, and evaluate the physical-chemical stability, in vitro antioxidant activity and in vitro safety profile of liquid crystalline systems (LCS) and microemulsions (MEs) with and without organic cocoa (OC) extract. LCS stabilized by surfactant polyoxyethylene 20 cetyl ether, containing water and oleic acid were studied. LCS and MEs were characterized using polarized light microscopy, small angle X-ray scattering, rheology and in vitro bioadhesion, and were evaluated for a period of 30 days by visual aspects, centrifuge test, pH value and relative density. PLM and SAXS assays showed the presence of domains of MEs, cubic and hexagonal mesophasephases, varying the proportions of the components of the formulations; where in the addition of the extract did not change rheological behavior of the formulations. All of the formulations were stable in the period analyzed and presented higher bioadhesive strength. In vitro antioxidant activity suggests that LCS and MEs presented a high capacity to maintain the antioxidant activity of OC extract. The results showed that the incorporation of OC in LCS improved the safety profile, according to cytotoxicity assays of systems may be a promising platform to OC extract for topical application for the potential treatment of skin disorders.

Development of nanotechnology-based drug delivery systems with olive vegetable oil for cutaneous application

ABSTRACT Liquid-Crystalline Systems represent active compounds delivery systems that may be able to overcome the physical barrier of the skin, especially represented by the stratum corneum. To obtain these systems, aqueous and oily components are used with surfactants. Of the different association structures in such systems, the liquid-crystalline offer numerous advantages to a topical product. This manuscript presents the development of liquid-crystalline systems consisting, in which the oil component is olive oil, its rheological characterizations, and the location of liquid crystals in its phase map. Cytotoxic effects were evaluated using J-774 mouse macrophages as the cellular model. A phase diagram to mix three components with different proportions was constructed. Two liquid crystalline areas were found with olive oil in different regions in the ternary diagram with two nonionic surfactants, called SLC1 (S1) and SLC2 (S2). These systems showed lamellar liquid crystals that remained stable during the entire analysis time. The systems were also characterized rheologically with pseudoplastic behavior without thixotropy. The texture and bioadhesion assays showed that formulations were similar statistically (p < 0.05), indicating that the increased amount of water in S2 did not interfere with the bioadhesive properties of the systems. In vitro cytotoxic assays showed that formulations did not present cytotoxicity. Olive oil-based systems may be a promising platform for skin delivery of drugs.

RESUMO Os cristais líquidos representam um sistema de liberação de substâncias ativas capazes de vencer a barreira cutânea, representada especialmente pelo estrato córneo. Água, óleo e tensoativos são misturados para se obter esses sistemas. Diferentes estruturas podem ser formadas nesses sistemas, as quais oferecem muitas vantagens para os produtos de uso tópico. Esse trabalho visou ao desenvolvimento de sistemas líquido-cristalinos preparados com óleo de oliva, sua caracterização reológica e a identificação das fases cristalinas no diagrama ternário. Efeitos citotóxicos foram avaliados usando células de rato como modelo celular. Construiu-se um diagrama de fases que mistura três componentes em diferentes proporções. Duas áreas de cristal líquido, denominadas SLC1 (S1) e SLC2 (S2), foram encontradas com óleo de oliva em diferentes regiões no diagrama ternário preparado com dois diferentes tensoativos não-iônicos. Esses sistemas mostraram fase cristalina lamelar, que permaneceu estável durante o tempo estudado. Os sistemas foram também caracterizados reologicamente e apresentaram comportamento pseudoplástico com tixotropia. Os ensaios de textura e bioadesão mostraram que as formulações foram similares (p < 0.05), indicando que o aumento da quantidade de água em S2 não interferiu nas propriedades bioadesivas dos sistemas. Os ensaios de citotoxicidade mostraram que as formulações não foram citotóxicas. Sistemas à base de óleo de oliva são interessantes para a liberação de fármacos na pele.

Formulation and Evaluation of Repaglinide Buccal Tablet: Ex Vivo Bioadhesion Study and Ex Vivo Permeability Study.

The present work was performed to develop and evaluate buccal tablet containing antidiabetic drug (Repaglinide). Ethyl cellulose was used as backing membrane and Carbopol 934p, Polyox wsr N-80 NF, HEC and HPC was used as bucco adhesive polymer. Aspartame was used as sweetener. Thickness, Hardness, weight variation and drug uniformity were investigated. The tablet formulations were also subjected to drug release in 250ml 6.8 phosphate buffer. Ex vivo bioadhesion, retention time and permeation through porcine buccal mucosa membrane. Effects of different bucco adhesive polymer were evaluated on release and bioadhesion, retention time and permeation of drugs. F5 formulations showed maximum amounts of drugs release (87.18%) at the end of 10 h dissolution study. F5 also showed maximum bioadheion (0.0754N) and the resident time of F5 formulation was 9.2 h. It shows 41.52% drug release after 10 h permeation study through porcine buccal mucosa mounted in Franz cell. The tablet also found stable in human saliva after 10hr. The tablet was not showed any type of physical changes after the completion of 10 h. The results of the study suggested that new buccal tablet formulations of combined bucco adhesive polymers can be suitably developed as an alternate to conventional dosage forms.

Bioadhesive buccal gels impregnated with fluconazole: formulation, in vitro and ex vivo characterization.

This study describes the formulation of bioadhesive buccal gels for fluconazole delivery via buccal mucosa. In the present study the polymer with well-defined mucoadhesive properties like Carbopol 934 was used. Carbopol- Poloxamer gels of 1% fluconazole was formulated with various absorption enhancers like polyethylene glycol, propylene glycol, glycerol, phosphatidylcholine, mannitol and sodium lauryl sulphate by cold method. The gels were characterised for gelation temperature, bioadhesive force, pH, viscosity, drug release profile, ex vivo permeation across goat buccal mucosa and stability profile. The percent drug permeated through the buccal mucosa was in the range of 62-76%. Polyethylene glycol and propylene glycol were found to be better absorption enhancers as compared to others and followed zero order release kinetics.

In vitro and in vivo adhesion properties evaluation carbomer six kinds bioadhesive material / 中国药学杂志

OBJECTIVE: To comprehensively evaluate bioadhesive properties these materials by testing adhesion properties in vitro and in vivo. METHODS: Mucin from porcine stomach model, homemade adhesion measuring device and intestinal propulsion were used for in vitro and in vivo evaluation adhesive materials. RESULTS: Carbomer 934P and HPMCK100M with high viscosity had optimal adhesion in their class, besides chitosan can be specifically bound by mucin from porcine stomach and it performed better than other materials in vivo adhesion. CONCLUSION: Above researches indicate that the bioadhesive properties had a positive correlation with viscosity in the same type material, and the relative molecular mass the materials, moisture absorption capacity, specific binding mucin and other factors should be considered in different types materials in the comprehensive evaluation.

Progress in research of chitosan derivatives in bioadhesive drug delivery system / 中国药学杂志

OBJECTIVE: To review the applications and progress in research of chitosan derivatives in bioadhesive drug delivery system.

Formulation and in vitro evaluation of mucoadhesive controlled release matrix tablets of flurbiprofen using response surface methodology

The objective of the current study was to formulate mucoadhesive controlled release matrix tablets of flurbiprofen and to optimize its drug release profile and bioadhesion using response surface methodology. Tablets were prepared via a direct compression technique and evaluated for in vitro dissolution parameters and bioadhesive strength. A central composite design for two factors at five levels each was employed for the study. Carbopol 934 and sodium carboxymethylcellulose were taken as independent variables. Fourier transform infrared (FTIR) spectroscopy studies were performed to observe the stability of the drug during direct compression and to check for a drug-polymer interaction. Various kinetic models were applied to evaluate drug release from the polymers. Contour and response surface plots were also drawn to portray the relationship between the independent and response variables. Mucoadhesive tablets of flurbiprofen exhibited non-Fickian drug release kinetics extending towards zero-order, with some formulations (F3, F8, and F9) reaching super case II transport, as the value of the release rate exponent (n) varied between 0.584 and 1.104. Polynomial mathematical models, generated for various response variables, were found to be statistically significant (P<0.05). The study also helped to find the drug's optimum formulation with excellent bioadhesive strength. Suitable combinations of two polymers provided adequate release profile, while carbopol 934 produced more bioadhesion.

O objetivo do presente estudo foi formular comprimidos mucoadesivos de flurbiprofeno, de liberação controlada, e otimizar o perfil da liberação do fármaco e a bioadesão, utilizando a metodologia de superfície de resposta. Prepararam-se os comprimidos via técnica de compressão direta, que foram avaliados in vitro quanto aos parâmetros de dissolução e da força bioadesiva. Planejamento com componente central para dois fatores em cinco níveis cada foi empregado para esse estudo. Carbopol 934 e carboximetilcelulose sódica foram tomados como variáveis independentes. Efetuaram-se estudos de espectroscopia por transformada de Fourier (FTIR) para observar a estabilidade do fármaco durante a compressão direta e para avaliar a interação a fármaco-polímero. Aplicaram-se vários métodos cinéticos para avaliar a liberação do fármaco dos polímeros. Gráficos de superfície de contorno e de resposta foram efetuados para retratar a relação entre as variáveis dependentes e a resposta. Os comprimidos mucoadesivos de flurbiprofeno apresentaram cinética de liberação não-fickiana, estendendo para ordem zero, para algumas formulações (F3, F8 e F9), alcançando transporte super caso II, à medida que o valor do expoente (n) de taxa de liberação variou entre 0,584 e 1,104. Modelos matemáticos polinomiais, gerados por diversas variáveis de resposta, foram estatisticamente, significativos (P<0,05). O estudo também auxiliou a encontrar a formulação ótima do fármaco, com excelente força de bioadesão. Combinações adequadas dos dois polímeros resultaram em perfis de liberação adequado, sendo que o Carbopol 934 produziu mais adesão.

Formulation development and characterization of mucoadhesive patch of atenolol.

The buccal region of oral cavity is an attractive site for administration of drug of choice. Buccal route is an excellent for systemic delivery of drug providing great bioavailability. A significant reduction in dose and dosing frequency can be achieved, thereby reducing dose dependent side effects, patient compliance and prolonging duration of action.Buccal dosage form increase bioavailability and prevent first pass metabolism of drug. The present study involves formulation and evaluation of patch of atenolol using chitosan with a hydrophilic polymer like PVP K-30 in various proportions and combinations fabricated by solvent casting technique. Propylene glycol has been used as plasticizer as well as penetration enhancer. Atenolol an antihypertensive drug which undergoes first pass metabolism with t ½ 6-7 hrs.. Various physicomechanical parameters like weight variation, thickness, folding endurance, drug content, water vapour transmission moisture content, moisture absorption, in vitro and ex vivo drug release, in-vitro permeation, stability in simulated saliva and various mucoadhesion parameters like mucoadhesive strength, force of adhesion and bond strength were evaluated. The swelling percentage was found to be function of solubility of drug and PVP K-30. The mucoadhesive strength, vapour transmission and in-vitro release of water soluble drug through water insoluble chitosan base matrix were found satisfactorily. All the fabricated patches were able to sustain for 6 hrs and the optimized formulation obeyed Korsmeyer-Peppas release kinetics. The physical appearance of patch was examined by scanning electron microscopy.

Enhanced Bioavailability of Nimodipine from Bioadhesive Buccal Bilayered Patches in Human Volunteers.

Aims: The objective of the present study was to develop a bioadhesive bilayered buccal patch of Nimodipine (15 mg) using Eudragit Rs 100 as secondary layer and a primary layer with Hydroxy propyl methyl cellulose and Hydroxy propyl cellulose JF. Methodology: Bilayered buccal patches were prepared by solvent casting technique. The absence of physiochemical interactions between NMDP and the polymer were investigated by differential scanning calorimetry (DSC). Bilayered buccal patches of NMDP were evaluated for in vitro drug permeation through porcine buccal membrane, in vitro drug release, moisture absorption, surface pH, mechanical properties and in vitro bioadhesion. Results: The results indicated that suitable bioadhesive bilayered buccal patches with desired permeability could be prepared. The bioavailability study was performed in healthy humans in a crossover experimental design. Bioavailability studies revealed that nimodipine possessed good buccal absorption. The relative bioavailability of the optimized buccal patch was found to be 205% in comparison to 30 mg marketed oral tablet. The formulation CC3 showed 68.84 ± 1.4% release and 46.85 ± 5.1% of drug permeated through porcine buccal membrane in 4 hr. A good correlation was seen between percentage in vitro release the extent of bioavailability for nimodine buccal patch. Conclusion: An improvement of bioavailability was obtained by buccal route to the extent of 2.05 times higher than that of oral route for NMDP. Hence, the development of a bioadhesive bilayered buccal patch for NMDP might be a promising one, as the necessary dose of drug could be decreased, resulting less side effects. Good ex vivo - in vivo correlation was obtained for NMDP.

Diltiazem-loaded buccoadhesive patches for oral mucosal delivery: Formulation and in vitro characterization.

The objective of the present study was to develop and evaluate bioadhesive buccal patches for mucosal delivery of diltiazem. The antihypertensive agent, diltiazem, undergoes first pass metabolism which compromises its bioavailability and the buccal route is a viable alternative to bypass this metabolism. In the present study, the buccal patches were fabricated with Eudragit L100 as the film forming polymer and hydroxypropyl methylcelluose, Carbopol 934 and sodium carboxymethylcellulose as the mucoadhesive polymer. The patches were characterized for various physicochemical attributes viz., weight uniformity, surface pH, folding endurance, swelling profile, content uniformity, permeability study, in vitro drug release profile and stability study in saliva. The results indicate that the Carbopol 934 is suitable for fabricating buccoadhesive patches with requisite release and stability profile.

Evaluation of Cedrela gum as a binder and bioadhesive component in ibuprofen tablet formulations

The compressional, mechanical and bioadhesive properties of tablet formulations incorporating a new gum obtained from the incised trunk of the Cedrela odorata tree were evaluated and compared with those containing hydroxypropylmethylcellulose (HPMC). Compressional properties were evaluated using Hausner's ratio, Carr's Index, the angle of repose, and Heckel, Kawakita and Gurnham plots. Ibuprofen tablets were prepared using the wet granulation method. Bioadhesive studies were carried out using the rotating cylinder method in either phosphate buffer pH 6.8 or 0.1 M hydrochloric acid media. The gum is a low viscosity polymer (48 cPs), and Fourier transform infrared spectroscopy revealed the presence of a hydroxyl group. Py and Pk values, which are measures of plasticity, showed the gum to be significantly (p<0.05) more plastic than HPMC, and plasticity increased with polymer concentration. All tablet formulations were non-friable (<1.0%), and the formulations containing the gum had a higher crushing strength (130.95 N) than those containing HPMC (117.85 N) at 2.0% w/w binder. Formulations incorporating the gum were non-disintegrating and had a significantly longer drug release time than those containing HPMC. At the highest binder concentration, Cedrela gum formulations adhered to incised pig ileum longer than those containing HPMC. Cedrela gum exhibited better compressive, flow and binding properties than HPMC and is suitable as a bioadhesive and for sustained release of drugs.

Propriedades de compressão, mecânicas e de formulações de comprimidos bioadesivos, que incorporam nova goma de mascar obtidas a partir de incisão de tronco da árvore de Cedrela odorata, foram avaliadas e comparadas com aquelas contendo hidroxipropilmetilcelulose (HPMC). Propriedades de compressão foram avaliadas usando a razão de Hausner, índice de Carr, ângulo de repouso e os gráficos de Heckel, Kawakita e Gurnham. Prepararam-se comprimidos de ibuprofeno utilizando o método de granulação a úmido. Realizaram-se estudos de bioadesividade utilizando o método de cilindro rotativo em tampão fosfato pH 6,8, ou meio ácido com 0,1 M de ácido clorídrico. A goma é um polímero de baixa viscosidade (48 cPs) e a espectroscopia no infravermelho por Transformada de Fourier (FTIR) revelou a presença de um grupo hidroxila. Valores de Py e Pk, que são medidas de plasticidade, mostraram que a goma é significativamente (p <0,05) mais plástica do que HPMC e que a plasticidade aumenta com a concentração de polímero. Todas as formulações de comprimidos mostraram-se não-friáveis (<1,0%) e aquelas contendo a goma apresentaram maior resistência ao esmagamento (130.95N) do que aquelas contendo HPMC (117.85N) em 2,0% (p/p) do ligante. As formulações que incorporaram a goma eram não-desintegrantes e apesentaram tempo de liberação significativamente maior do que aquelas contendo HPMC. As formulações de goma de Cedrela aderiram à incisão de íleo de porco por tempo maior do que aquelas contendo HPMC com a maior concentração de ligante. A goma Cedrela apresentou melhor fluxo, compressão e propriedades de ligação do que HPMC e é adequada como bioadesivo e para a liberação sustentada de fármacos.

Isolation and characterization of novel mucoadhesive biomaterial from Phoenix dactylifera.

Phoenix dactylifera belongs to the family Arecaceae. The current aim of our research work is to isolate bio-material from the fruit pulp of Phoenix dactylifera and evaluate its mucoadhesivity. The bio- material was isolated by simple economical process. The isolated biomaterial was subjected for determination of solubility, colour changing point, viscosity, surface tension, pH and chemical tests. The mucoadhesivity of the biomaterial was assessed by shear stress method and rotating cylinder method using Capra aegagrus labium and intestine as mucosal substrates. The results were compared with HPMC and sodium CMC. The research study revealed that the biomaterial from Phoenix dactylifera exhibits promising inbuilt mucoadhesivity. So it can serve as a powerful natural mucoadhesant and may be used to develop mucoadhesive transmucosal drug delivery systems.

Isolation and characterization of novel mucoadhesive biomaterial from Phoenix dactylifera.

Phoenix dactylifera belongs to the family Arecaceae. The current aim of our research work is to isolate bio-material from the fruit pulp of Phoenix dactylifera and evaluate its mucoadhesivity. The bio- material was isolated by simple economical process. The isolated biomaterial was subjected for determination of solubility, colour changing point, viscosity, surface tension, pH and chemical tests. The mucoadhesivity of the biomaterial was assessed by shear stress method and rotating cylinder method using Capra aegagrus labium and intestine as mucosal substrates. The results were compared with HPMC and sodium CMC. The research study revealed that the biomaterial from Phoenix dactylifera exhibits promising inbuilt mucoadhesivity. So it can serve as a powerful natural mucoadhesant and may be used to develop mucoadhesive transmucosal drug delivery systems.

Preparation of bioadhesive cyclosporine a ocular nanostructured lipid carriers and its ocular distribution in rabbits / 中国药学杂志

OBJECTIVE: To develop a bioadhesive nanostructured lipid carrier (P407-NLC) for ocular delivery of cyclosporine A and investigate its ocular distribution in rabbits. METHODS: Melt-emulsification method was chosen to prepare CsA-NLC. Poloxamer 407 (P407) was dissolved in borate buffer solution (pH 8.0), then added into CsA-NLC to prepare P407-NLC. The morphology of P407-NLC was observed by transmission electron microscopy (TEM). The mean particle size and Zeta potential were measured by laser particle size analyzer. The viscosity was measured by rheometer. Dialysis method was employed to investigate the in vitro release of CsA from P407-NLC at 34°C. The concentrations of CsA in ocular tissues were studied by RP-HPLC, and the pharmacokinetic parameters were calculated by linear trapezoidal method. The topical ocular irritation study of P407-NLC was carried out in rabbits. RESULTS: The obtained P407-NLC was approximately spherical in shape with average particle size of (41.2 ± 0.2) nm and Zeta potential of (-15.2 ± 0.21) mV, and P407 was coated on the appearance of NLC. P407-NLC was non-newtonian fluids. The in vitro release of CsA from P407-NLC was slowed down and fitted well with single exponential distribution model. AUC0-24h of CsA in cornea, aqueous humor and iris after ocular administration of P407-NLC containing 6.0% P407 were 10.75, 4.45 and 4.62 times higher than that of CsA oil solution, and 2.77, 1.22 and 1.54 times higher than that of CsA-NLC, respectively. MRTs in aqueous humor, cornea and iris were 3.28, 2.26 and 3.46 times higher, respectively, than that of CsA oil solution, and 1.69, 1.50 and 1.62 times higher than CsA-NLC, respectively. There was no irritation for P407-NLC to rabbit eyes. CONCLUSION: P407-NLC can be used to increase the level of CsA in ocular tissues and would be a promising nanocarrier for ocular drug delivery. Copyright 2012 by the Chinese Pharmaceutical Association.

Formulation and evaluation of buccoadhesive quetiapine fumarate tablets

The aim of present study was to develop and evaluate buccoadhesive Quetiapine Fumarate (QF) tablets, which is extensively metabolised by liver. Buccoadhesive tablets of QF were prepared using HPMC K4M, HPMC K15M and combination of carbopol and HPC as mucoadhesive polymers by direct compression method. Sodium deoxycholate was added to formulation to improve the permeation of drug. The formulations were tested for bioadhesion strength, ex vivo residence time, swelling time and in vitro dissolution studies and ex vivo permeation studies. Optimized formulation (F3) showed 92% in vitro release in 8 h and 67% permeation of drug through porcine buccal mucosa and followed fickian release mechanism with zero order kinetics. FTIR studies of optimized formulation showed no evidence of interaction between the drug and polymers. In vivo mucoadhesive behaviour of optimized formulation was performed and subjective parameters were evaluated.

O objetivo do presente estudo foi desenvolver e avaliar os comprimidos bucoadesivos de fumarato de quetiapina (FQ), que é extensivamente metabolizada no fígado. Os comprimidos bucoadesivos de FQ foram preparados utilizando-se HPMC K4M, HPMC K15M e a combinação de carbopol e HPC como polímeros mucoadesivos pelo método de compressão direta. O desoxicolato de sódio foi adicionado à formulação para melhorar a permeação do fármaco. As formulações foram testadas quanto à força de bioadesão, tempo de residência ex vivo, tempo de inchamento, dissolução in vitro e permeação ex vivo. A formulação otimizada (F3) mostrou 92% de liberação in vivo em 8 h e 67% de permeação do fármaco através da mucosa bucal de porco e seguiu o mecanismo fickiano de liberação com cinética de ordem zero. Os estudos de FTIR da formulação otimizada não mostraram evidência da interação entre o fármaco e os polímeros. O comportamento mucoadesivo in vivo da formulação otimizada foi efetuado e avaliaram-se os parâmetros subjetivos.

Mechanism responsible for mucoadhesion of mucoadhesive drug delivery system: a review.

Mucoadhesion had been a topic of interest in the design of drug delivery system to prolong the residence time of the dosage form with the under lying absorption surface to improve and enhance the bioavailability of drugs. Mucoadhesion occurs between two surfaces, one of which is a mucous membrane and another is drug delivery system. Pharmaceutical aspects of mucoadhesion had been the subject of great interest during recent years because mucoadhesion could be a solution for bioavailability problems that result from a too short length of stay of the pharmaceutical dosage form at the absorption site within the gastro-intestinal tract. It had been a great challenge to the pharmaceutical sciences in order to enhance localised drug delivery or to deliver ‘difficult’ molecules (proteins and oligonucleotides) into the systemic circulation. Mucoadhesive systems remain in close contact with the absorption tissue, the mucous membrane releasing the drug at the action site leading to increase in bioavailability (both local and systemic effects). Extending the residence time of a dosage form at a particular site and controlling the release of drug from the dosage form are useful especially for achieving controlled plasma level of the drug as well as improving bioavailability. The main objective of this study was to selectively collect the data which were extended the gastrointestinal residence time of the dosage form and controlled the release of mucoadhesives.

Mucoadhesive drug delivery systems / Sistemas de entrega de drogas mucoadesiva

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.

O efeito de fármacos pode ser potencializado através do desenvolvimento de novos sistemas de liberação como os sistemas mucoadesivos. Estes sistemas permanecem em contato íntimo com o tecido de absorção, as mucosas, liberando o fármaco no local de ação, com o consequente aumento da biodisponibilidade, podendo promover efeitos locais e sistêmicos. A mucoadesão, atualmente, é explicada por seis teorias, a eletrônica, da adsorção, da molhabilidade, da difusão, da fratura e a mecânica. Para estudar seus mecanismos e quantificá-la, são propostas várias metodologias in vitro e in vivo. Porém, a mucoadesão ainda não é totalmente compreendida. Esse trabalho tem por objetivo revisar os mecanismos e as teorias envolvidas na mucoadesão, além de descrever as metodologias e os polímeros mais utilizados em sistemas mucoadesivos para liberação de fármacos.

Elementos conceptuales para estudiar el comportamiento bioadhesivo en polímeros / Conceptual elements to study the bioadhesive behavior in polymers

La bioadhesión es un fenómeno interfacial que ocurre entre un material polimérico y una superficie biológica. Las interacciones entre las fases son el resultado tanto de las propiedades del polímero como de la naturaleza del sustrato. En este documento se estudian los aspectos teóricos fundamentales que permiten entender los mecanismos que se proponen para la interpretación del fenómeno desde cada una de las teorías existentes, considerando los factores que determinan el comportamiento bioadhesivo de un polímero y las características del sustrato. Finalmente se analizan las técnicas experimentales existentes para determinar la bioadhesividad en materiales poliméricos y las aplicaciones en el diseño de algunos sistemas terapéuticos farmacéuticos.

The bioadhesion is an interfacial phenomenon ocurring between a polymer and a biological surface. Due to the complex nature of polymers and molecules present in the biological surfaces, many factors determine the strength and duration of the adhesion. However, the specific interactions in the polymer/biological substrate interface are governed by both, the properties of the polymer and the nature of the substrate. In this document the theoretical fundamentals of the current mechanisms that have been proposed to explain bioadhesion are reviewed. Also, the main factors determining the bioadhesive behavior of a polymer and the properties of the substrate are discussed. Finally, the experimental techniques to evaluate the bioadhesion in polymers are analyzed, and the applications in some therapeutic pharmaceutical systems presented.

Determination of in Vitro Adhesion and Dissolution Rate of Total Puerariae Flavones(TPF)Bioadhesive Sustained-release Tablets / 中国药房

OBJECTIVE:To study the dissolution rate of total puerariae flavones(TPF)bioadhesive sustained-release tablet,and to determine its bioadhesive force to animal stomach and small intestine in vitro METHODS:Using rotating basket method,the dissolubility summation was determined with 0 1mol/L HCl as dissolution medium at speed of 100r/min,single-index model,Weibull distributing model,Higuchi equation and zero-class model were used to imitate the dissolution curve The biggest absolute error,the biggest relative error and AIC were used as comprehensive indices to select the best imitating model A new apparatus made by ourselves was used to compare the adhesive force between the sustained-release tablets and popular tablets in adhering to rabbits'stomach or small intestine RESULTS:The results showed that the dissolution rate in vitro imitated in single-index model was the best Bioadhesion study showed that there were obvious differences between bioadhesive sustained-release tablets and non-bioadhesive tablets in adhering with gastric mucosa and small intestines mucosa(P