Dissertations / Theses on the topic 'Extrusion-spheronization'

Transarterial chemoembolization (TACE) has been practiced in patients for over 30 years and describes the infusion of chemotherapeutic agents followed by embolic particles. This infusion is normally performed by selecting tumor feeding arteries with a catheter under image guidance. The overall goal of TACE is to deliver a high dose of drug directly to a tumor, prevent drug clearance, and induce ischemic necrosis of the tumor. The limitations for current beads system including non-biodegradable and biodegradable beads used for TACE are low drug loading and only water soluble drug can be loaded in beads. The drug loading methods used in current beads system were ion-exchange method and expanding-loading-shrinking method, but these methods didn't allow loading high drug content (up to 10% drug loading) and water insoluble drug. The other limitation for current biodegradable beads used for TACE only had narrow size range beads. In those instances where treatment is not complete or the tumor recurs, physicians would like to be able to access a tumor on multiple occasions in order to administer additional TACE treatments as needed. It may not be possible to re-enter the feeding artery once this artery had been occluded by non-biodegradable beads. For overcoming above limitations, the goal in this study is developing a new biodegradable bead which should have wide size range, achieve high drug loading and high drug loading efficiency, and load water soluble and water insoluble drug. Extrusion/spheronization technology was chosen for drug loading method. It must be noted that not every polymer can be successfully extruded and spheronized. Oxidized cellulose (OC) was chosen in this study, which is biodegradable polymer. OC was evaluated as new excipient for extrusion/spheronization in this study. Differential scanning calorimetry (DSC) and dynamic vapor sorption analysis were used to compare the interaction and distribution of water within MCC and OC. The amounts of nonfreezing and freezing water in hydrated samples were determined from melting endotherms obtained by DSC. The moisture sorption profiles were analyzed according to the GAB equations. The adsorbed monolayer was not statistically different for MCC and OC after accounting for the amorphous content of the polymers. These results suggest that OC can act as a “molecular sponge,'' and thus aid in the production of beads by extrusion and spheronization. A composite central design was used to evaluate the influence of spheronizer speed, spheronizer time and water level (granulation liquid,) on pellet yield and sphericity. All factors as well as the interactions between water level and spheronizer speed were significant (P<0.05) for sphericity. And water level was significant (P<0.05) for pellet yield. The water insoluble drug, methotrexate (MTX), was used in this study. The drug content of OC and OC/carbopol beads was up to 40% and drug loading efficiency was 100%. The swelling ratio of the MTX loaded OC/carbopol beads were up to 200%, and the swelling ratio was decreased when drug content was increased. Comparing to commercial embolization produce Contour SE, OC and OC/carbopol beads were significantly more compressible. Recoverability of OC/carbopol beads is close to Contour SE. The beads stability increased with an increase in the MTX content. 100-900 μm beads could be delivered through from 18G to 23G needles. The release method involved the use of a T-Apparatus where the drug experiences an element of diffusion through a static environment. This method was developed to resemble the in -vivo situation in embolization procedures more closely. Release results showed from 57% to 78% MTX was released from OC/carbopol beads in 6 days depending on the drug content. OC as new pelletization aid can be used to produce beads by using extrusion/spheronization. The new biodegradable OC base beads have wide size range, achieve high drug loading (up to 40%) and high drug loading efficiency, and are able to load water soluble and water insoluble drug. Physical and mechanical properties of MTX loaded OC base beads match the requirement for catheter deliverability. The result of release study showed slow release. The biodegradable OC base beads are suitable for TACE.

Doctor Pharmaceuticae - DPharm
The popularity and increasing complexity of sustained release dosage forms has resulted in increased costs to the patient. One approach to achieve cheaper, yet effective, sustained release medication is through the simplification of production processes. Matrix tablets have been used to sustain the release of numerous drugs and are cheap to prepare. Since they are single-unit dosage forms, however, they display less predictable transit through the gastrointestinal tract. Hence, they provide less reliable blood levels of the drug in comparison with multi particulate dosage forms. Of the various types of multiparticulates available, pellets are popular for oral administration. A fairly recent innovation, in pelletization technology, is extrusion and spheronization. With this technique it is possible to produce pellets with a high degree of drug loading directly and rapidly. The drug loaded beads are usually coated for a sustained release effect. If one could omit the coating step, it would avoid many problems (thus reducing the number of quality control procedures required) and save chemicals, labour and capital for the purchase of additional equipment. The primary aim of this project was to investigate the preparation of non-coated, spheronized sustained release pellets, while a secondary aim was to prepare beads that can be compressed into sustained release tablets. A tablet can accommodate a larger mass and the compaction forces involved may enhance the sustained release effect. Several techniques were used in an attempt to sustain the release of drugs of different solubilities. In one series of formulations, a novel method was used to incorporate a binder consisting of ethylcellulose in ethanol. Using this technique, the release of Theophylline was sustained for approximately 8 hours. In other formulations, several materials were added to beads with the aim of forming sustained release matrixes. Only magnesium stearate was able to prolong the release of Acetaminophen and Theophylline for a reasonable time. In an attempt to explain why materials that were successfully used in sustained release matrix tablets were of very limited value in beads, an equation was developed to calculate the approximate distance between the retardant particles. Calculations using this equation revealed that the retardant particles were too far apart, within each bead, to expect consolidation to occur. The discrete retardant particles do not retard drug release effectively. Eudragit?-containing beads, which sustained the release of the drug to a small extent, were successfully compressed into tablets, both on their own and in combination with non pareil seeds. In each case, the sustained release effect was improved by compaction. In the case of the products manufactured with non pareil seeds, the tablets disintegrated rapidly to release the beads, thus ensuring that the advantages of multiparticulates were maintained. Because it was realised that a large amount of the matrix material could not be incorporated within the beads if a high dose drug was formulated with Avicel? PH 101, the idea of forming the matrix outside the beads was developed. Several materials were tried in an attempt to form a sustained release external matrix. Eudragit? RSPO prolonged the dissolution of Theophylline for more than four hours. Magnesium stearate was able to sustain the release of Acetaminophen and Theophylline appreciably. In the latter case, the dissolution, in water, of a standard adult dose of the drug was prolonged for more than 12 hours. However, the dissolution in an acidic medium was much faster. The described technique represents an advance in extrusion and spheronization technology. While beads containing Cutina? HR did not show promise as sustained release units, they compacted to form sustained release tablets of good appearance and acceptable strength. These tablets were considered to have been efficiently prepared because the constituent beads were easily manufactured and showed good flowability, and because a glidant and a lubricant were not required. The production of sustained release Indomethacin beads with a more steady release profile than the innovator's product has also been described in other experiments. The research described in this thesis represents progress towards the widespread commercial production of effective non-coated sustained release beads and may encourage further work towards this goal.

Microcrystalline cellulose (MCC) is the most commonly used excipient in the manufacture of spherical particles or beads by extrusion spheronisation. However, the use of MCC in beads has its limitations such as prolonged release of drugs due to lack of disintegration. The aim of this study was to determine if Aloe vera and Aloe marlothii leaf materials can be used as excipients in the production of beads prepared by extrusion spheronisation. A 23 full factorial design was employed for optimisation and to explore the effects of the concentration of MCC, polyvinylpyrrolidone and aloe materials on the sphericity and release rate of ketoprofen. Scanning electron microscopy revealed more porous beads when aloe materials were included in the bead formulations compared to the formulation with MMC alone. The bead formulations containing aloe materials exhibited faster drug release compared to that of the formulation containing MCC alone. Dissolution data of the optimised formulations were analysed in terms of mean dissolution time (MDT) as well as fit factors (f1 and f2). The optimised bead formulations had dissolution profiles comparable to that of the formulation containing MCC alone at pH 1.2 and 4.5 (f2 values > 70), but less comparable to the reference at pH 6.8 (50 < f2< 65) due to faster drug release. Aloe vera and Aloe marlothii leaf materials can be used successfully together with MCC in the production of beads by extrusion spheronisation.
Thesis (MSc (Pharmaceutics))--North-West University, Potchefstroom Campus, 2013.

L'amélioration de la dissolution des médicaments peu solubles présente de nombreux défis.Dans cette thèse, un procédé d'extrusion-sphéronisation a été étudié en profondeur pour améliorer la dissolubilité du médicament avec une formulation de nano-émulsion. Le but du travail de thèse est de décrire les propriétés et les procédés de fabrication de minigranules permettant d'augmenter la solubilité des principes actifs peu solubles dans l'eau et donc d‘améliorer leur biodisponibilité lors de l'administration par voie orale, pour deux modèles de molécules différentes qui sont l‘acide folique (vitamine peu soluble dans l'eau) et le kétoprofène (anti-inflammatoire non stéroïdien qui présente une solubilité limitée dans les fluides gastriques à cause de son pKa (classe II dans le système de classification biopharmaceutique – BCS, ayant une action anti-inflammatoire, antalgique et antipyrétique). Cette étude décrit la préparation par extrusion-sphéronisation, caractérisation et étude de dissolution in vitro d'acide folique et de pastilles de kétoprofène revêtues de Acryl-EZE®, Advantia® Performance dans un minicoatère à lit fluidisé. Les résultats des essais ont montré la faisabilité de la préparation de pastilles enrobées entériques contenant un AINS et que, en revêtant le système multiparticulaire avec Acryl-EZE® 93A92545 et Advantia® Performance190024HA49 à un gain pondéral de 17,5%, 12,0%, respectivement, du médicament à partir des pastilles peuvent être obtenus. Les résultats des essais de dissolution ont indiqué que dans un milieu acide, le revêtement de film a entraîné un retard dans la libération du médicament, alors qu'aucun retard n'a été observé dans un milieu tampon à pH 6,8
Improvement in dissolution of poorly soluble drugs has many challenges.In this thesis, an extrusion-spheronization process was thoroughly studied forimproving dissolubility of drug with nano-emulsion formulation.The aim of the thesis work is to describe the properties and manufacturing processes ofpellets to increase the solubility of poorly soluble active ingredients in water and thus improvetheir bioavailability when administered orally: folic acid (water-insoluble vitamin) andketoprofen (Non-steroidal anti-inflammatory, having anti-inflammatory, analgesic andantipyretic action, class II in the Biopharmaceutical Classification System).This study describes the preparation by extrusion-spheronization, characterisation andin vitro dissolution study of folic acid and ketoprofen pellets. Ketoprofen pellets coated withAcryl-EZE®, Advantia® Performance in a fluid-bed minicoater. The results of the tests showedthe feasibility of the preparation of enteric-coated pellets containing a NSAID and that bycoating the multiparticulate system with either 17.5% Acryl-EZE® 93A92545 or with 12%Advantia® Performance 190024HA49 weight gain, an enteric release of the drug from thepellets can be obtained. The results of dissolution testing indicated that in acidic media, entericfilm coating resulted in a delay in the release of the drug, while no delay was observed in pH6.8 buffer media

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Pellets are spherical solid oral dosage forms that can be used in the development of new pharmaceutical products with standardized plant extracts. Brosimum gaudichaudii Trécul (Moraceae) and Lafoensia pacari A. St.-Hil. (Lythraceae) are typical species from the Cerrado biome. The extract obtained from the roots of B. gaudichaudii is traditionally used in the treatment of vitiligo, its effectiveness is due to the presence of the chemical markers psoralen and bergapten. As for L. pacari, the barks of the branches and trunk are traditionally used in the treatment of gastric ulcers, highly valued for there anti-inflammatory and wound healing because of there ellagic acid content. For each of these species optimal extractive methods exist to obtain standardized liquid extracts. However there are no studies that propose the development of solid oral dosage forms from them. Thus, the present study is aimed at obtaining pellets from the standardized liquid extract of the B. gaudichaudii roots, furthermore to determine the efficiency of a photoprotector coating on the stability of psoralen and bergapten and also obtaining pellets with standardized liquid extract of the L. pacari barks from the branches and trunk. The B. gaudichaudii roots were collected in the city of Jussara, Goiás, and the L. pacari barks in Niquelândia, Goiás. Separately, the raw materials were cleaned, dried in an oven with forced air circulation, then subsequently milled for the extractive process. After the standard liquid extract of B. gaudichaudii had been obtained, six formulas were developed at bench scale. Among these, one stood out by the homogeneity of the lot and the sphericity of its pellets. This formula had been selected to be sacaled-up and it`s composition had been formed by 49.5% (w/w) of microcrystalline cellulose (MCC), 1% (w/w) of hydroxypropylmethyl cellulose (HPMC) and 49.5% (w/w) of that extract. The pellets obtained from the scaled formula were divided into two portions, one of them had been coated with a photoprotective layer and both were subjected to a photostability test. The degradation of the markers had been evident only in the uncoated pellets. The reduction of 1.87% (w/w) in the content of psoralen and 8.1% (w/w) in bergapten content had been observed after 3 J/cm2 exposure to UVB radiation. After exposing to 30 J/cm2 of UVA, there had been a reduction of 24.1% (w/w) of psoralen and 28.48% (w/w) of bergapten. Therefore, the application of the photoprotective coating had been an effective alternative and ensured the stability of the chemical markers after the test. With respect to the liquid extract of L. pacari, 13 formulas were obtained among which only two formed pellets whose batch homogeneity had been greater than 70%. Among them, only one had been chosen to obtain the first scaled-up model. With the production of the scaled-up batch, it had been observed that formulas prepared with a lower proportion of standardized liquid extract of L. pacari had enabled us to obtaing more homogeneous, spherical and a smoother pellets. Based on these results and due to the innovative character of the studies, this work can be used as a model for future trials designed to obtain pellets with standardized liquid extract of B. gaudichaudii or L. pacari.
Pellets são formas farmacêuticas sólidas orais esféricas que podem ser utilizadas no desenvolvimento de novos produtos farmacêuticos a partir de extratos vegetais padronizados. Brosimum gaudichaudii Trécul (Moraceae) e Lafoensia pacari A. St.-Hil. (Lythraceae) são espécies típicas do bioma Cerrado. O extrato obtido das raízes de B. gaudichaudii é utilizado tradicionalmente no tratamento de vitiligo, cuja eficácia se deve pela presença dos marcadores químicos psoraleno e bergapteno. Quanto à espécie L. pacari, são tradicionalmente utilizados as cascas dos galhos e do tronco no tratamento de úlceras gástricas, cuja ação anti-inflamatória e cicatrizante é atribuída ao ácido elágico. Para cada uma destas espécies existem métodos extrativos otimizados para obtenção de extratos líquidos padronizados nos respectivos marcadores químicos. No entanto, não há estudos que proponham o desenvolvimento de formas farmacêuticas sólida orais a partir destes. Assim, o presente trabalho teve como objetivo obter pellets a partir do extrato hidroalcoólico das raízes de Brosimum gaudichaudii, padronizado em psoraleno e bergapteno, determinar a eficácia do revestimento fotoprotetor na estabilidade do psoraleno e bergapteno, além de obter pellets com o extrato hidroalcoólico das cascas dos galhos e do tronco de Lafoensia pacari, padronizado em ácido elágico. As raízes de B. gaudichaudii foram coletadas no município de Jussara, Goiás, e as cascas dos galhos e do tronco de L. pacari em Niquelândia, Goiás. Separadamente, as matérias-primas vegetais foram limpas, secas em estufa com circulação forçada de ar, posteriormente trituradas para a obtenção dos respectivos extratos líquidos padronizados. A partir do extrato líquido padronizado de B. gaudichaudii, foram obtidas seis fórmulas em escala de bancada. Dentre estas, uma se destacou pela homogeneidade do lote e pela esfericidade dos pellets. Deste modo, a fórmula que se destacou foi selecionada e escalonada, sua composição é formada pela mistura de XX% (m/m) de celulose microcristalina (CMC), X% (m/m) de hidroxipropilmetilcelulose (HPMC) e 49,5% deste extrato. Os pellets obtidos a partir da fórmula escalonada foram divididos em duas partes, em uma foi aplicado o revestimento fotoprotetor e ambas foram submetidas ao ensaio de fotoestabilidade. Desse modo, a degradação dos marcadores foi evidente apenas nos pellets sem o revestimento, cuja redução de no teor de psoraleno e bergapteno foi igual a 1,87% (m/m) e 8,1% (m/m), após a exposição a 3 J/cm2 de radiação UVB. Após a exposição a 30 J/cm2 de UVA, houve a redução de 24,1% (m/m) de psoraleno e 28,48% (m/m) de bergapteno. Portanto, a aplicação do revestimento fotoprotetor foi uma alternativa eficaz e garantiu a estabilidade dos marcadores químicos após o ensaio. Com relação ao extrato líquido de L. pacari, foram obtidas 13 fórmulas, dentre as quais apenas duas formaram pellets cuja homogeneidade dos lotes foi superior a 70% e apenas uma foi escolhida como modelo para a obtenção do lote piloto. Com a produção do lote piloto foi observado que fórmulas elaboradas com menor proporção do extrato padronizado de L. pacari e a mecanização do processo de mistura dos componentes da fórmula, possibilitam a obtenção de pellets mais esféricos, homogêneos e com superfície menos irregular. Diante dos resultados obtidos e devido ao caráter inovador dos estudos realizados, este trabalho pode ser utilizado como modelo para ensaios futuros destinados a obtenção de pellets com o extrato líquido padronizado de B. gaudichaudii ou L. pacari.

Sistemas monolíticos particulados contendo os constituintes ativos veiculados na forma de grânulos revestidos - pellets - têm recebido crescente atenção nos últimos anos, em função da otimização na biodisponibilidade e segurança na liberação do fármaco. A utilização destas unidades, como componentes de comprimidos traz, como principal vantagem, a divisibilidade da forma sem a perda do perfil biofarmacêutico desejado para o fármaco. Para sua produção, é indispensável a manutenção da integridade do revestimento daquelas unidades. Uma estratégia para o alcance deste objetivo envolve a utilização de grânulos inertes deformantes, comprimidos em conjunto com os grânulos revestidos, que atuam como um sistema de amortecimento das forças de compressão. Neste trabalho investigou-se a produção de grânulos deformantes através de dois métodos de granulação por via úmida, avaliando a influência de adjuvantes sobre as características dos produtos obtidos. Empregando a técnica de extrusão/esferonização obtiveram-se grânulos com propriedades de fluxo, empacotamento e resistência mecânica aceitáveis. O efeito dos adjuvantes sobre as etapas tecnológicas foi estudado por meio de um planejamento fatorial. Testaram-se duas variedades de celulose microcristalina, os desintegrantes croscarmelose sódica e crospovidona e soluções aglutinantes aquosas e hidroetanólicas de povidona. Para o desenvolvimento dos comprimidos utilizaram-se, como modelo, grânulos revestidos gastro-resistentes contendo omeprazol. A influência da composição dos grânulos deformantes sobre a liodisponibilidade do fármaco dos comprimidos foi avaliada através de análise fatorial 23. Os grânulos deformantes protegeram o revestimento polimérico dos pellets com diferentes intensidades.
Monolythic particulate systems containing the active constituents as coated pellets became great interest due to the improvement of safety and bioavailability. The use of such units as components of tablets shows as main advantages the divisibility of the pharmaceutical dosage form without loosing the desired biopharmaceutical profile of the drug. Consequently for the tablet production, the integrity of the polymeric film must be attained. A strategic option involves the utilization of inert soft pellets, which could be compressed together with the film coated pellets, absorbing the compaction forces. In this work the production of soft pellets was investigated using two wet granulation methods and evaluating the influence of formulation adjuvants on the pellets properties. The extrusion/spheronization technique yielded pellets with acceptable flow, packing and mechanical characteristics. The influence of the adjuvants on the technological steps was carried out through a statistical designed experiment. Microcrystalline cellulose from two producers, the disintegrants sodium croscarmellose and crospovidone, and aqueous and hydroethanolic dispersions of povidone, as binder, were tested. For the tablets development omeprazol gastroresistant film coated pellets were used as model. Aiming at the study of the influence of the soft pellets composition on drug lyoavailability was performed a 23 factorial experiment. The soft pellets protected at different intensities the polymeric coating of the gastroresistant pellets.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Inflammatory bowel diseases are chronic conditions that affect different portions of the gastrointestinal tract. The treatment of these conditions aims to induce and maintain the remission of the symptoms, controlling recurrences. The clinical efficacy of the treatment can be enhanced using colon-specific drug release systems, since they allow topical treatment, lower systemic drug absorption and therefore increase the safety of therapy. The use of time-dependent polymers, such as ethylcellulose, and/or polymers that can be degraded by colonic bacteria, such as pectin, are both strategies used to develop colonic drug delivery systems. The association of these strategies has been performed in order to further increase the efficiency of the systems. Thus, the aim of the present work was develop pellets and matricial tablets containing different amounts of ethylcellulose and pectin for colon-specific release of prednisone. Pellets were obtained by extrusion-spheronization method and were evaluated for wet mass processability, sphericity, size distribution, flowability and drug content. Hydroethanolic mixtures and alcoholic or aqueous dispersions (Surelease®) of ethylcellulose were tested as granulation liquid. The release profiles of prednisone from pellets were determined using the apparatus III of the United States Pharmacopoeia, simulating the path of the dosage form through the gastrointestinal tract. The drug release from the pellets seems to be dependent on the ethylcellulose dispersion in the matrix, which was defined by the production method used. The addition of ethylcellulose in ethanol gave rise to a prednisone sustained release profile, whereas its incorporation as a dry powder resulted in rapid drug release. The use of ethylcellulose aqueous dispersion (Surelease®) resulted in an intermediate release performance. Furthermore, the amount of granulation liquid and its ethanol concentration have affected the shape of the pellets. Lower ethanol concentration (24%) impaired the spheronization of extrudates. Granulation liquid prepared with 40% ethanol enabled the formation of spherical pellets, but with reduced mechanical stability. The appropriate amount of solution prepared with 35% ethanol resulted in formulations with spherical shape and adequate mechanical strength. The sphericity of the pellets affected their flowability. In addition, tablets containing pectin and ethylcellulose were prepared by wet granulation or direct compression. The average weight, content uniformity and in vitro release from the tablets were evaluated. The tablets obtained by direct compression have provided better control release compared to those prepared by wet granulation. The reduction of particle size of the ethylcellulose in the tablets prepared by direct compression was critical to increasing the efficiency of the system. Thus, tablets prepared with ethylcellulose finer fraction (diameter <180μm), containing 20% pectin showed the highest efficiency of colon-specific drug release. These systems may represent a simple option for the control of inflammatory bowel disease.
As doenças inflamatórias intestinais são condições patológicas crônicas que afetam diferentes porções do trato gastrointestinal. O tratamento dessas condições objetiva induzir e manter a remissão dos sintomas, controlando as recidivas. A eficácia clínica dos tratamentos pode ser aumentada pelo emprego de sistemas de liberação cólon-específica, pois os mesmos possibilitam a realização de tratamento tópico, reduzem a absorção sistêmica dos fármacos e, por isso, aumentam a segurança da terapia. O emprego de polímeros de liberação tempo-dependente, como a etilcelulose, e a utilização de materiais degradáveis especificamente pela microbiota colônica, como a pectina, são duas importantes estratégias usadas no desenvolvimento de sistemas colônicos de liberação. A associação destas estratégias tem sido realizada no intuito de aumentar a eficiência de liberação dos sistemas. Dessa forma, foram desenvolvidos no presente trabalho, pellets e comprimidos matriciais contendo diferentes proporções de etilcelulose e pectina, para liberação cólon-específica de prednisona. Os pellets foram obtidos pelo método da extrusão-esferonização e foram avaliados quanto à processabilidade da massa úmida, esfericidade, distribuição de tamanho, fluxo e teor. Misturas hidroetanólicas e dispersões alcoólicas ou aquosas (Surelease®) de etilcelulose foram testadas como líquido de granulação. Os perfis de liberação da prednisona a partir de pellets contidos em cápsulas foram obtidos utilizando o aparato III da Farmacopéia Norte-Americana, simulando o trajeto da forma farmacêutica pelo trato gastrointestinal. O controle da liberação a partir dos pellets se mostrou dependente do grau de dispersão da etilcelulose na matriz e, por sua vez, este dependeu do método de incorporação usado. A adição de etilcelulose dispersa em etanol proporcionou liberação prolongada da prednisona, ao passo que sua incorporação à seco resultou na liberação rápida do fármaco. A adição de etilcelulose na forma de dispersão aquosa (Surelease®) proporcionou desempenho de liberação intermediário. Além disso, a quantidade de líquido de granulação e a concentração de etanol neste afetaram a forma dos pellets. Menor concentração de etanol no líquido de granulação (24%) dificultou a esferonização dos extrusados. Por outro lado, a adição de líquido com 40% de etanol possibilitou a formação de pellets esféricos, mas com reduzida estabilidade mecânica. O uso de quantidade adequada de solução preparada com 35% de etanol resultou em formulações esféricas e com resistência mecânica adequada. A esfericidade dos pellets afetou diretamente seu fluxo. Adicionalmente, foram obtidos comprimidos contendo pectina e etilcelulose pelos métodos de granulação úmida e compressão direta e os mesmos foram avaliados quanto ao peso médio, teor, uniformidade e liberação in vitro. Os comprimidos obtidos por compressão direta propiciaram melhor controle de liberação quando comparado aos obtidos por granulação via úmida. A redução no tamanho das partículas de etilcelulose na matriz obtida por compressão direta foi fundamental para aumentar a eficiência do sistema. Dessa forma, comprimidos preparados com fração fina de etilcelulose (diâmetro < 180μm), contendo 20% de pectina e obtidos por compressão direta apresentaram a mais alta eficiência de liberação cólon-específica. Esses sistemas podem representar opção simples para o controle das doenças inflamatórias intestinais.

O presente trabalho teve como objetivos produzir um extrato seco de Ilex paraguariensis por spray-drying, em escala semi-industrial, e desenvolver grânulos esferoidais a partir do extrato seco, pelo método de extrusão/esferonização, bem como caracterizar as propriedades físicas, químicas e tecnológicas e investigar a estabilidade dos principais constituintes polifenólicos de ambos produtos frente à radiação UVC e ao calor. O extrato seco apresentou partículas esféricas (tamanho médio de 19,6 μm), com superfície lisa, boas propriedades de fluxo e rendimento satisfatório (67 %). No teste de fotoestabilidade, o extrato seco se manteve estável frente à radiação UVC, por 48 h, nos diferentes materiais de acondicionamento (frascos de vidro âmbar, frascos de vidro transparente ou vidros de relógio). No teste de estabilidade acelerada (40 ºC, 75 % de umidade relativa, 4 meses), o extrato seco demonstrou ser higroscópico e sensível ao calor, especialmente quando acondicionado em frascos de polietileno, por serem permeáveis à umidade. Os grânulos esferoidais, por sua vez, apresentaram tamanho médio de 1,10 mm, forma e rendimento (78,7 %) satisfatórios, boa dissolução em água (89,44 a 100,05 %) e adequada recuperação (> 95 %) do conteúdo de polifenóis totais em relação ao extrato seco. Os grânulos esferoidais foram estáveis frente à radiação UVC quando acondicionados em frascos de vidro âmbar, entretanto, o teor de polifenóis totais foi reduzido quando as amostras foram acondicionadas em vidro de relógio ou em frascos de vidro transparente. No teste de estabilidade acelerada, os grânulos esferoidais demonstraram ser higroscópicos e sensíveis ao calor. Este efeito foi mais pronunciado quando as amostras foram acondicionadas em frascos permeáveis (de polietileno) do que em frascos impermeáveis (de vidro transparente). Os resultados apontam para a importância da redução da umidade residual tanto do extrato seco quanto dos grânulos esferoidais, bem como para a necessidade de acondicioná-los em embalagens com proteção contra a umidade e a luz, sob baixas temperaturas.
The present work was designed to produce a dry extract of Ilex paraguariensis by the spray-drying process, in semi-industrial scale, and to develop pellets from dry extract, by the extrusion/spheronization method, as well as to characterize the physical, chemical and technological properties and to investigate the stability of the main polyphenol constituents from both products against UVC radiation and heat. The dry extract presented spherical particles (mean size of 19.6 μm), with smooth surface, good flow properties and satisfactory yield (67 %). In the photo stability test, the dry extract remained stable against UVC radiation, for 48 h, in all packaging material (amber glass bottles, transparent glass bottles or open-dishes). In the accelerated stability testing (40 ºC, 75 % relative humidity, 4 months), the dry extract demonstrated to be hygroscopic and sensible to the heat, especially when conditioned in polyethylene ethyl bottles because they are permeable to the humidity. The pellets presented mean size of 1.10 mm, satisfactory shape and yield (78.7 %), good dissolution in water (89.44 to 100.05 %) and good recovery (> 95 %) of the total polyphenol content in comparison with dry extract, the pellets were stable against UVC radiation when conditioned in amber glass bottles, however, the total polyphenol content was reduced when the samples were conditioned in open-dishes or in transparent glass bottles. In the accelerated stability testing, the pellets demonstrated to be hygroscopic and sensible to the heat. This effect was more pronounced when the samples were conditioned in permeable flasks (polyethylene ethyl bottles) than in semi-permeable flasks (transparent glass bottles). These findings point to the relevance of reducing the residual moisture of both dry extract and pellets, as well as to the necessity of conditioning both into opaque humidity tight packing, at low temperatures.

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Inflammatory bowel diseases (DII) are pathological conditions that affect the gastrointestinal mucosa. Crohn's disease and ulcerative colitis are the most prevalent DII. The current therapy for these diseases aimed to control relapses and are based on the oral administration of anti-inflammatory drugs, immunosuppressants, antibiotics and biological agents. These agents have been used chronically and generally have low efficacy and significant systemic side effects. The use of herbal medicines has shown good results in the treatment of inflammatory diseases, including DII. The Bidens pilosa L. is a species widely used in Brazilian popular medicine and some studies have proven its anti-inflammatory effect. Another strategy to improve DII treatment is to target the active compounds to the colon, thus ensuring the topical treatment of inflammatory diseases, with greater efficiency and safety. Objective: The objective of the present work was to develop multiparticulate systems (pellets) coated with pH-dependent and/or time-dependent polymers, to provide colonic release of the constituents of the Bidens pilosa extract. Materials and Methods: Two different commercial extracts of Bidens pilosa (glycolic and hydroethanolic) were purchased and characterized. These extracts were then concentrated on rotaevaporator under reduced pressure. The amount of total polyphenols was determined by Folin-Ciocauteau colorimetric reaction. Then, microcrystalline cellulose pellets were obtained by extrusion-spheronisation technique using concentrated extracts as binder. The pellets were coated in a fluidized bed with different polymers (ethylcellulose, Opadry® 94k and Eudragit® FS30D). Morphological, size and flow rate analysis were performed and polyphenols content in pellets was determined. Finally, in vitro release of the polyphenols was determined. Results and Discussion: The concentration step resulted in products with total polyphenol content 5 times higher compared to the original extracts. The concentrated extracts were successfully used as a binder in the pellet preparation by extrusion-spheronization. Pellets prepared with the glycolic extract and coated with ethylcellulose showed vacuoles in the coat layer and released almost 100% in 120 minutes. On the contrary, pellets containing the hydroethanolic extract coated with 28% ethylcellulose showed only 30% of polyphenol released after 6 h of experiment; however, these pellets showed incomplete drug release at the end of the experiment. In view of these results, the pellets containing hydroethanolic extract were also coated with Eudragit® FS 30D or Opadry® 94k. The in vitro drug release showed no colon-specific release of polyphenols, even in the absence of glycerin. Then, an internal layer of ethylcellulose (10% weight gain) and an external coat of Eudragit FS30D were applied on the pellets. This association resulted in an increase in the colon-specific release efficiency and this formulation should be further studied aiming its future use as a phytomedicine to the treatment of the inflammatory bowel diseases.
As doenças inflamatórias intestinais (DII) são condições patológicas que acometem a mucosa do trato gastrointestinal, sendo suas principais representantes a doença de Crohn e a retocolite ulcerativa. A terapia atual para essas doenças objetiva o controle das recidivas e é baseada na administração oral de antiinflamatórios, imunossupressores, antibióticos e agentes biológicos. O tratamento dessas doenças é crônico e está relacionado a ocorrência de importantes efeitos adversos oriundos da absorção sistêmica dos fármacos. O uso de plantas medicinais tem apresentado bons resultados no tratamento das doenças inflamatórias, aumentando o interesse pelo desenvolvimento de formas farmacêuticas contendo esses produtos de origem vegetal. A espécie Bidens pilosa L. (picão-preto) é bastante utilizada na medicina popular brasileira e estudos tem comprovado o seu efeito antiinflamatório, inclusive em modelos de inflamação intestinal. O tratamento das DII pode ser melhorado não apenas pelo uso de materiais vegetais, mas também pelo desenvolvimento de sistemas capazes de liberar os compostos ativos especificamente no cólon, garantindo assim o tratamento local seguro e eficiente dessas doenças. Objetivo: O presente trabalho teve como objetivo o desenvolvimento e avaliação de pellets revestidos com polímeros de liberação pH ou tempo-dependente capazes de proporcionar liberação cólon-específica dos constituintes do extrato da Bidens pilosa. Materiais e Métodos: Dois diferentes extratos de Bidens pilosa (extrato glicólico e hidroetanólico) foram adquiridos comercialmente e caracterizados quanto ao teor de polifenóis totais e teor de sólidos. Esses extratos foram então concentrados em rotaevaporador, sob pressão reduzida, e o teor de polifenóis totais nessas preparações foi determinado pelo emprego da reação colorimétrica de Folin-Ciocauteau. Em seguida, pellets de celulose microcristalina foram obtidos pela técnica de extrusão-esferonização, utilizando os extratos concentrados como líquido aglutinante. Os pellets foram então revestidos em leito fluidizado com diferentes polímeros (etilcelulose, Opadry 94k, Eudragit FS30D, ou ainda a associação de etilcelulose + Eudragit FS30D). As caracterizações morfológica, granulométrica, de fluxo e do teor de polifenóis nos pellets foram realizadas. Por fim, a liberação in vitro dos marcadores vegetais foi determinada em aparato III de dissolução da Farmacopéia Norte-Americana. Resultados e Discussão: Os extratos concentrados apresentaram teor de polifenóis totais cerca de cinco vezes maior em comparação com os extratos originais e foram utilizados, com sucesso, na obtenção de pellets. O revestimento dos pellets com os diferentes polímeros aumentou sua esfericidade, diâmetro médio e melhorou seu fluxo. O tipo de extrato (glicólico ou hidroetanólico) incorporado nos pellets afetou a funcionalidade e estrutura dos filmes de revestimento constituídos por etilcelulose, com formação de vacúolos e liberação rápida dos polifenóis (quase 100% em 120 minutos), observada a partir dos pellets contendo extrato glicólico. A liberação prematura dos polifenóis foi evitada pelo emprego do extrato hidroetanólico em pellets revestidos com 28% de ganho de massa de etilcelulose. Esses pellets liberaram cerca de 30% de polifenóis após 6 horas de ensaio, mas a liberação ao final do experimento (10 horas) foi de apenas 46%. Adicionalmente, os pellets contendo extrato hidroetanólico foram revestidos com dois diferentes polímeros acrílicos de solubilidade pH-dependente, o Opadry®94k e o Eudragit® FS 30D. No entanto, esses pellets também apresentaram liberação prematura dos polifenóis, apesar da ausência de glicerina na formulação. Dessa forma, foi proposta a associação da etilcelulose (10% de ganho de massa, como revestimento interno) com o Eudragit FS30D. Os pellets revestidos com essa associação mostraram aumento na eficiência de liberação cólon-específica dos polifenóis presentes nos extratos de Bidens pilosa, e devem ser adicionalmente estudados visando seu futuro emprego como medicamento fitoterápico para o tratamento das doenças inflamatórias intestinais.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Ketoprofen is a nonsteroidal anti-inflammatory drug used for the treatment of mild to moderate pain in chronic inflammatory conditions. Due to its superior potency ketoprofen can be used in the treatment of inflammatory bowel disease (IBD). The treatment of IBD becomes safer and more effective when the drug is incorporated into colon-specific drug delivery systems. Pellets are multiparticulate solid dosage forms extensively investigated as colon-specific drug delivery systems. Pellets can be introduced into capsules or compressed into tablets. The industrial production of tablets containing pellets has several advantages when compared to the production of capsules. However, the compression of the pellets should not affect the release of the drug and the tablets should quickly disintegrate following administration. Therefore, the aim of this study was to develop tablets containing ketoprofen coated pellets for colon-specific drug release. For this, pellets were produced by extrusion and spheronization technique containing 40% (w / w) ketoprofen. Ketoprofen pellets obtained were coated with two different pH - dependent polymers derived from methacrylic acid (Opadry ® k 94 or Eudragit ® FS 30D) with weight gains of 10 or 20% (w / w). The coated pellets were then compressed under different pellets’ amounts and different compression forces. An extra- granular mixture of lactose and microcrystalline cellulose was used as compression aid. The in vitro release of ketoprofen from the systems obtained was evaluated in Bio Dis ® apparatus. The morphological and physical properties of pellets and tablets were assessed. The Eudragit ® FS 30 D coated pellets with weight gains of 10 or 20% showed higher efficiency of colon-specific delivery (94 %), however, the drug was released slowly and incompletely in conditions mimicking the pH of the colonic region. After compression of the pellets, the efficiency of colon – specific drug delivery was lowered after compression (between 20% and 61%, depending on the formulation). The lowest decrease of colon specific efficiency was observed in formulations containing lower amount of pellets, which also produced disintegrating matrices with potential for use in the topical treatment of IBD.
O cetoprofeno é um antiinflamatório não esteroidal usado para o tratamento de dores leves a moderadas, em condições inflamatórias crônicas. Devido a sua elevada potência antiinflamatória, o cetoprofeno pode ser aproveitado no tratamento das doenças inflamatórias intestinais (DII). O tratamento das DII se torna mais seguro e eficaz quando o fármaco é incorporado em sistemas de liberação cólon-específica. Pellets são formas farmacêuticas multiparticuladas bastante investigadas como sistemas de liberação cólon-específica. Após sua produção, os pellets podem ser inseridos em cápsulas ou comprimidos. A produção industrial de comprimidos contendo pellets apresenta inúmeras vantagens quando comparada ao processo de enchimento de cápsulas. No entanto, a compressão dos pellets não deve afetar as características de liberação do fármaco e os comprimidos formados devem se desintegrar rapidamente. Dessa forma, o objetivo deste trabalho foi desenvolver comprimidos contendo pellets revestidos para liberação cólon-específica de cetoprofeno. Para tanto, foram produzidos pellets contendo 40% (p/p) de cetoprofeno e celulose microcristalina pela técnica de extrusão e esferonização. Os pellets de cetoprofeno obtidos foram revestidos com dois diferentes polímeros pH-dependentes, ambos derivados do ácido metacrílico (Opadry ® 94 k ou Eudragit ® FS 30) com ganhos de massa 10 ou 20% (p/p). Os pellets revestidos foram então comprimidos com diferentes cargas de pellets e submetidos a diferentes forças de compressão, utilizando como adjuvante extra-pellets uma mistura granulada de lactose e celulose microcristalina. A liberação in vitro do cetoprofeno a partir das formas farmacêuticas obtidas foi avaliada em dissolutor Bio Dis aparato III. As caracterizações morfológicas e físicas dos pellets e comprimidos foram conduzidas. Os pellets obtidos por revestimento com Eudragit ® FS 30 D, com ganhos de massa de 10 ou 20%, mostraram elevada eficiência de liberação cólon-específica in vitro (até 94%), no entanto, o fármaco foi liberado de forma lenta e incompleta em meio com pH similar ao encontrado na região colônica. Após a compressão dos pellets, os valores de eficiência de liberação cólon-específica sofreram reduções entre 20% e 61%. A menor diminuição da eficiência de liberação cólon-específica foi observada nas formulações contendo a menor carga de pellets, as quais deram origem à matrizes desintegráveis com potencial para utilização no tratamento tópico das DII.

O objetivo do presente trabalho foi desenvolver e avaliar péletes para compor sistema multiparticulado contendo ácido ascórbico, bem como validar metodologia analítica por cromatografia líquida de alta eficiência (CLAE) para aplicação em ensaio de dissolução destas formas farmacêuticas. A técnica de extrusão-esferonização foi utilizada por ser de fácil aplicação a nível laboratorial e industrial obtendo-se péletes matriciais, compostos de Methocel® K4M, Methocel® K100M e Eudragit® L 100, e péletes de liberação convencionais, para revestimento em leito fluidizado com Kollicoat® SR 30 D como agente regulador da liberação do fármaco. O sistema multiparticulado foi preparado na forma de comprimido pela compressão dos péletes com menor nível de revestimento, avaliando-se o nível de força aplicada e a presença da Microcel® 101 como protetor da camada de revestimento. Os péletes obtidos foram caracterizados quanto à esfericidade por análise imagem, friabilidade, dureza e perfil de dissolução comparativo com apresentações comerciais. Os péletes matriciais foram obtidos com grau de dificuldade variável em função do polímero utilizado, porém apresentaram esfericidade e resistência mecânica adequadas. O perfil de dissolução destas formulações demonstrou que não houve controle na liberação do fármaco, mesmo naquelas onde havia maior concentração de polímero. Os péletes revestidos com três níveis de polímero (5,07; 8,26 e 10,35% em relação à massa do pélete) apresentaram boas características granulométricas e o perfil de dissolução daqueles revestidos com 5,07% de polímero demonstrou semelhança com o da apresentação comercial. O perfil de dissolução comparativo entre os péletes isolados e os comprimidos obtidos sem a presença de excipiente mostrou que ocorre dano na camada de revestimento nos maiores níveis de força de compressão aplicada. Para os comprimidos obtidos a partir da mistura de péletes e Microcel® 101 este fato não foi observado, indicando que a presença do excipiente é fundamental para a manutenção da integridade da camada de revestimento além de promover a desintegração parcial dos comprimidos.
The present work aimed to develop and evaluate pellets to compound a multiparticulate system containing ascorbic acid, as well as, validate analytic methodology through high performance liquid chromatography and evaluate the essay of dissolution from these dosage forms. The extrusion-spheronization technique was used for its laboratorial and industrial application to obtain matrix pellets compounds of Methocel® K4M, Methocel® K100M, Eudragit® L 100, and conventional release pellets, for fluid bed coating with Kollicoat® SR 30 O as a regular occurrence release agent for the drug. The multiple system was prepared in tablets through the compression of the pellets with a lower coating levei, evaluating its applied compression force and the presence of Microcel® 101 as a protector of the coating layer. The obtained pellets were characterized according to its roundness through image analysis, friability, hardness and dissolution profile compared with those marketed products. The matrix pellets were obtained on varied difficulty degree due to the polymer utilized, even through they presented adequate spheroid and mechanical properties. The dissolution profile of these formulations didn\'t show any control in the release of the drug even in those, which had a high concentration of the polymer. The pellets coated with three polymers leveis (5,07%, 8,26% and 10,35% related to the pellets mass) presented good sphericity, and the dissolution profile of those pellets coated with 5,07% polymer demonstrated similarity with those ones marketed products. The comparative dissolution profile among isolated pellets and the tablets obtained without excipients presence, showed that damage right occur on the higher compression force levei is applied. This fact is not observed on the tablets obtained from the pellets blend and Microcel®101, which indicates that the presence of the excipients is fundamental for the maintenance and integrity of the coating layer, moreover, it causes the partial disintegration of the tablets.

No
The aims of the present work were to pelletize talc by extrusion-spheronization technique using microcrystalline cellulose (MCC) as a pelletization aid and to study its performance as a neutral substrate for coating. A 32 factorial design was used to study the effect of independent variables (X1, amount of talc, and X2, MCC) on pellet properties.

Trabalho Final de Mestrado Integrado, Ciências Farmacêuticas, Universidade de Lisboa, Faculdade de Farmácia, 2014
The extrusion/spheronization technology has already proved to have great potential for the production of multiparticulate dosage forms. The present work is dedicated to the study of the effects of different binders and different granulation fluids on pellets preparation, as well as in their properties and drug release. In this research, the production of pellets containing mixtures of different amounts (5%, 25% and 45%), of paracetamol or carbamazepine (which were used as model drugs) and microcrystalline cellulose was evaluated. In each batch different granulation fluids were used (water or a mixture of isopropanol/water) as well as different polymers as binders. Extrusion was carried out with a radial screen extruder, maintaining the same processing conditions: extrusion speed was kept to 20-50 rpm and the extrusion was performed twice. After spheronization, the pellets obtained were dried and then evaluated in terms of their physical characteristics like density, mechanical strength, shape and size distribution. Drug release from prepared pellets was also evaluated. Carbamazepine was released from uncoated pellets (matrix pellets), while paracetamol pellets were coated with release retarding polymers (reservoir pellets) using fluidized bed technology before drug release was tested. A mixture of elthylcellulose (EC) and hidroxyproprylcellulose (HPC) was used to coat these pellets. The differences between each wetting liquid (water or IPA:water) and each polymer were evaluated. When formulations were granulated with only water, pellets became stronger and harder than the ones which had an isopropanol/water mixture in their formulation. The same way, when hydrophilic polymers were used in the formulation, the pellets produced were denser and harder to break. There are two major factors influencing the drug release: the porosity of the pellets and the polymer’s solubility. Depending on the percentage of the different components in the formulation of the pellets, one or the other factor plays a more relevant role. When the pellets’ formula had a large percentage of MCC, the porosity of the pellets was the main factor influencing the drug release, which led to a faster release from the pellets containing EC (more porous than the ones with HPMC). On the other hand, when pellets had a higher amount of binder, its’ solubility was the main factor controlling the release. Therefore, HPMC pellets released the drug faster than EC ones, since HPMC is a water soluble polymer.
A tecnologia de extrusão/esferonização já demonstrou ter um grande potencial para a produção de diversas formas farmacêuticas. Este estudo tem como objetivo estudar os efeitos de diferentes aglutinantes e diferentes líquidos de granulação na preparação de pellets, assim como nas suas propriedades e na libertação de fármaco. Neste trabalho, foram avaliados lotes de pellets produzidos com misturas de diferentes frações (5%, 25% e 45%) de paracetamol ou carbamazepina (que foram usados como fármacos modelo) e microcelulose cristalina. Em cada um destes lotes foram usados diferentes líquidos de granulação (água ou uma mistura de isopropanol/água), assim como diferentes aglutinantes. A extrusão foi realizada recorrendo a um extrusor de ecrã radial, mantendo sempre as mesmas mesmas condições de processamento: velocidade de extrusão mantida entre 20-50 rpm e a extrusão foi efetuada duas vezes consecutivas. Após esferonização, os pellets obtidos foram avaliados no que diz respeito às suas características físicas tais como densidade, forma, distribuição de tamanhos e força mecânica. Foram também realizados ensaios de libertação de fármaco a partir dos pellets produzidos. A carbamazepina foi libertada a partir de pellets sem revestimento (matrix pellets) enquanto que os pellets de paracetamol foram revestidos com polímeros de libertação prolongada (reservoir pellets), recorrendo a uma tecnologia de leito fluidizado antes do teste de dissolução para o fármaco. Foi usada uma combinação de etilcelulose (EC) e hidroxiproprilcelulose (HPC) para revestir estes pellets. Quando foi usada apenas água como líquido de granulação, os pellets obtidos mostraram-se mais duros e menos porosos do que os que foram produzidos com uma mistura de isopropanol e água. Da mesma forma, quando foram utilizados polímeros hidrofílicos na sua formulação, os pellets produzidos revelaram-se mais densos e mais difíceis de quebrar. Existem essencialmente dois fatores que influenciam a libertação do fármaco: a porosidade dos pellets e a solubilidade do polímero utilizado como aglutinante. Dependendo da percentagem dos diversos componentes na formulação dos pellets, um ou outro destes fatores irá dar um maior contributo. Quando a fórmula dos pellets era constituída por uma grande quantidade de MCC, a porosidade era o facto dominante, pelo que os pellets contendo EC libertaram o fármaco mais rapidamente (mais porosos do que os que com HPMC). Por outro lado, quando foi utilizada uma maior percentagem de aglutinante, a solubilidade do mesmo revelou-se o principal fator a influenciar a libertação do fármaco. Assim, os pellets com HPMC libertaram o fármaco mais rapidamente do que os com EC, uma vez que o primeiro é um polímero solúvel em água.

碩士
嘉南藥理科技大學
生物科技研究所
95
The purpose of this study is to prepare and evaluate enteric coated pellets after extrusion/spheronization. The various formulation variables studied, including pellet size, amount of enteric polymer (coating thickness) and soluble polymer/enteric polymer ratio were found to affect drug release kinetics in various dissolution media. Both Didanosine and Doxycycline Hyclate were used as model drugs. Didanosine (DDI) is known to be effective in the treatment of patients with HIV virus by inhibiting HIV replication. DDI is an acid labile drug, therefore it has to be coated with enteric polymer in order to protect the drug in the stomach and to be released in intestine. Doxycycline Hyclate belongs to Tetracyclines antibiotics. DXH is irritant to stomach, thus to release the drug in intestine via enteric coating is necessary to reduce adverse effects. In the process of preparing drug containing pellets, the uncoated pellets are formed using extrusion/spheronization methodology. The granulation solvent mixed with the model drug and water soluble materals, a binder, and a disintegrant, to form a wet mass. The wet mass was extruded/spheronized and then dried to form uncoated pellets. Enteric coating of model drug are available after polymer coating process. Various formulation variables, including pellet size, amount of enteric polymer (coating thickness) and soluble polymer/enteric polymer ratio were found to affect drug release kinetics. On the pellet size, formulations with larger size have slower release rate. Uncoated pellets have faster drug release, where as pellets with thicker polymer coating results in slower drug release. Finally, pellets with higher HPMCP/HPMC ratio of polymer coating results in slower drug release. According to the results, via adjusting appropriate formulation variables, delayed release of model drugs is achievable in order to avoid drug degradation and drug irritation in stomach.