• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 3
  • 2
  • Tagged with
  • 6
  • 6
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • 2
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Mise au point et évaluation des microparticules lipidiques solides en vue du développement galénique de préparations pour inhalation à libération prolongée/ Development and evaluation of solid lipid microparticles as sustained release system for pulmonary drug delivery

Jaspart, Séverine 26 January 2007 (has links)
Le développement de formes à libération prolongée destinées à ladministration pulmonaire est un domaine qui a, jusquà présent, été relativement peu étudié mais pour lequel il y a actuellement un intérêt croissant. Le but de notre travail est de développer une forme destinée à ladministration par inhalation qui libérerait de façon prolongée un agent bronchodilatateur. Dans le cadre de ce travail, les microparticules lipidiques solides (MLS) ont été choisies comme véhicule en vue de lobtention dune libération prolongée. Les MLS présentent en effet de nombreux avantages en termes de coûts de production, de stabilité et de biocompatibilité comparativement à dautres systèmes microparticulaires. Le salbutamol, principe actif ß2-mimétique choisi initialement pour cette étude, nétant pas suffisamment lipophile pour sincorporer de façon efficace dans les MLS, un dérivé plus lipophile du salbutamol, lacétonide de salbutamol (AS) a été synthétisé. Les caractéristiques physico-chimiques de lAS ont été déterminées, sa stabilité a été évaluée et des méthodes de dosage ont été mises au point. Des MLS vierges (non chargées en AS) ont tout dabord été produites après optimisation des paramètres de fabrication en vue dobtenir une taille adéquate pour ladministration par inhalation. Des études de tolérance au niveau pulmonaire effectuées in vivo sur des rats ont montré la biocompatibilité de ces MLS. Lactivité pharmacologique de lAS a été évaluée à la fois par des essais ex vivo de bronchodilatation sur organes isolés ainsi que par des essais daffinité (binding) envers les récepteurs ß1 et ß2-adrénergiques. Ces études nont malheureusement pas permis de conclure avec certitude quant à léventuel effet ß2-mimétique de lAS. Cependant, en raison de son caractère lipophile, lAS sera utilisé comme molécule modèle tout au long du processus de développement. LAS a donc été incorporé dans les MLS et les paramètres de production ont été étudiés et fixés par la méthodologie des plans dexpérience en vue doptimiser le pourcentage de particules possédant un diamètre géométrique convenant à ladministration par inhalation. La concentration en AS naffectant pas de façon significative la taille des MLS, celles-ci pourront être produites en utilisant la concentration en AS désirée. La caractérisation de ces MLS par microscopie électronique a montré que, lorsque la charge théorique initiale augmente, des cristaux dAS sont observés à lextérieur des MLS. Des essais de libération menés in vitro dans un premier temps puis ex vivo (en présence de fragments de poumons de porcs) ont permis de montrer une prolongation de la libération de lAS à partir des MLS comparativement à la libération à partir de mélanges physiques de MLS vierges et dAS. Ces résultats montrent la capacité des MLS possédant une taille pour administration pulmonaire, à libérer de façon prolongée la molécule qui y est incorporée. Cette libération est dautant plus prolongée que la charge en AS diminue. La présence denzymes pulmonaires na cependant pas modifié la cinétique de libération. Des poudres pour inhalation à base de MLS à 5% en AS ont été formulées en utilisant différents excipients porteurs et compétiteurs en différentes concentrations relatives. Les fractions respirables mesurées in vitro sont, dans le meilleur des cas, égales à 15%. Cependant, les MLS à 5% en AS administrées seules ont une fraction respirable proche de 25%. Leurs propriétés découlement savérant acceptables, il peut être envisagé dadministrer les MLS telles quelles en tant que poudre pour inhalation./ The sustained release of drugs for pulmonary delivery is a research field which has been so far rather unexploited but which is currently becoming increasingly attractive. The aim of this research work is to develop a pulmonary delivery system which will be able to sustain the release of a bronchodilator agent. Therefore, solid lipid microparticles (SLMs) were chosen in order to provide a sustained release to its incorporated substance. Indeed, this kind of drug carrier offers many advantages. In comparison with other microparticulate dosage forms, SLMs production costs are relatively low, they are physiologically compatible and their physical stability is well established. Salbutamol, a well-known short-acting ß2-adrenergic receptor agonist, was initially chosen for this study but this molecule proved to be not lipophilic enough to be efficiently incorporated into SLMs. Thats the reason why salbutamol acetonide (SA) was synthetized from salbutamol in order to get a more lipophilic molecule and thereby to increase the incorporation into SLMs. Then, the physico-chemical properties of SA were characterized, its stability was studied and chromatographic assays were developed. Drug free SLMs were produced using manufacturing parameters which were optimized in order to get particles with a suitable range of size for pulmonary administration. Tolerance studies were then carried out in vivo on rats to check SLMs biocompatibility in the respiratory tractus. Ex vivo tests using isolated organs were carried out in order to investigate the bronchodilating activity of SA. The obtained results were completed with a binding study to evaluate the affinity between SA on the one hand and ß1 and ß2-adrenergic receptors on the other hand. Unfortunately those studies didnt allow us to conclude about the possible ß2-mimetic activity of SA. Owing to its lipophilic character, SA will be used all along this research work as a model molecule for the development of SLMs as sustained release system for pulmonary delivery. SA was then incorporated into SLMs: the production parameters were studied using the methodology of experimental design in order to optimize the percentage of particles with a suitable diameter for pulmonary administration. It has been noticed that SA concentration does not affect significantly the particle size. So SLMs can be produced using the pre-established production parameters whatever the desired SA concentration. The characterization of the obtained SLMs-SA by scanning electron microscopy showed especially that SA crystals appear outside of the particles when the theoretical drug loading increases. Drug release studies were carried out both in vitro and ex vivo i.e. using fragments of porcine pulmonary tissues. These studies showed that SA release from SLMs is sustained in comparison with SA release from physical mixtures of drug free SLMs and SA. The obtained results tend to prove that produced SLMs are suitable carriers in order to get a sustained release of the incorporated substance. It has also been noticed that the release rate increases when the drug loading increases. Concerning the ex vivo studies, it may be concluded that the presence of pulmonary enzymes does not modify SA release profiles. Inhalation powders containing SLMs with 5% SA were finally developed using different carrier excipients and ternary agents at different relative concentrations. Respirable fractions were determined in vitro and proved to be at best equal to 15%. However, SLMs 5% SA have also been administered alone without any additional excipients. In this case, the obtained respirable fraction is close to 25%. Seeing that the flowability of SLMs 5% SA appeared to be acceptable, they could be administered just as they are as inhalation powder.
2

Nanocristais de furosemida: preparação, caracterização físico-química e avaliação in silico de absorção oral e pulmonar / Furosemide nanocrystals: preparation, physical-chemical characterization and in silico evaluation of oral and lung absorption

Barbosa, Savio Fujita 19 August 2014 (has links)
Segundo a Organização Mundial de Saúde, a hipertensão arterial é responsável por uma crise global de saúde pública, sendo as doenças cardiovasculares implicadas em aproximadamente 17 milhões de mortes/ano, das quais, 9,4 milhões ocasionadas por complicações provocadas pela hipertensão, como edema pulmonar. Quanto ao arsenal terapêutico disponível, a furosemida, potente diurético de alça, é amplamente utilizada em situações de controle e emergência relacionadas à hipertensão e ao edema pulmonar cardiogênico. Apesar do elevado índice de sua prescrição, esse fármaco pertence à classe IV do Sistema de Classificação Biofarmacêutica (SCB), apresentando absorções intestinais erráticas e variáveis. Tais características representam desafio para o desenvolvimento de formas farmacêuticas orais. Assim, adoção de tecnologias inovadoras associadas à via de administração pulmonar pode permitir abordagem terapêutica alternativa, com elevado potencial de aplicação. Entre as tecnologias inovadoras, a obtenção de nanocristais de fármacos classes II e IV tem sido promissora. Nanocristais podem exibir desempenho in vivo superior quando comparados aos seus homólogos, na forma micronizada. Portanto, estratégias que permitam o desenvolvimento de medicamentos contendo furosemida, com maior eficácia e segurança, são de fundamental importância. Nesse sentido, a aplicação de tecnologia in silico, com propriedade preditiva, contribui para a racionalização de ensaios na pesquisa e no desenvolvimento de novas formas farmacêuticas. Objetivou-se, desse modo, a preparação e a caracterização físico-química de nanocristais de furosemida e sua avaliação in silico na absorção oral e pulmonar empregando ferramenta computacional. Os nanocristais foram obtidos por moagem à alta energia, utilizando movimentos simultâneos de revolução/rotação. A determinação da distribuição do tamanho e a morfologia foram realizadas por difração de raios laser e microscopia eletrônica de varredura, respectivamente. As possíveis interações e/ou alterações do estado cristalino do fármaco foram investigadas por calorimetria exploratória diferencial, termogravimetria diferencial, difração de raio X e espectroscopia Raman de baixo deslocamento. Quanto à solubilidade do nanocristal, foram realizados ensaios para a determinação do aumento na solubilidade de equilíbrio e da velocidade dissolução, utilizando os métodos shake flask e velocidade de dissolução intrínseca (VDI), respectivamente. A moagem à alta energia permitiu a obtenção de nanocristais com tamanho médio trinta vezes menor (231nm) do que o tamanho inicial, na escala micrométrica (7,1 µm). Os nanocristais apresentaram estabilidade térmica. Não foram observadas interações entre os excipientes e os nanocristais, que, entretanto, exibiram estrutura cristalina menos definida, o que indica parcial amorfização do nanocristal. A solubilidade de saturação dos nanocristais aumentou aproximadamente três vezes; como consequência, houve aumento na VDI em 2,2 vezes, 1,8 vezes e 3,8 vezes, quando comparado à VDI da furosemida micronizada em meio SGF, tampão 4,5 e SIF, respectivamente. Quanto às avaliações in silico dos nanocristais, sua absorção oral revelou moderada alteração no perfil farmacocinético. Quando foi utilizada a via de administração pulmonar, os nanocristais apresentaram maior desempenho quando comparada a via de administração oral; destacando-se o aumento na Fa% e na Cmáx e a acentuada diminuição no Tmáx. Em conclusão, a plataforma tecnológica obtida tem potencial aplicação no desenvolvimento de formas farmacêuticas inovadoras para administração pulmonar de furosemida. / According to the World Health Organization, hypertension is responsible for global public health crisis, being the cardiovascular diseases involved in approximately 17 million deaths a year, of these, 9.4 million occasioned by hypertension complications such as pulmonary edema. Regarding therapeutic arsenal available, Furosemide is a potent loop diuretic widely used in control and emergency situations related to hypertension and cardiogenic pulmonary edema. Despite the high level of prescribing, this drug belongs a class IV drug, according to Biopharmaceutics Classification System (BCS), exposing erratic and variable intestinal absorption. These characteristics represent a challenge for the development of oral dosage forms. Thus, adoption of innovative technologies associated with pulmonary route of administration may allow an alternative therapeutic approach, with high potential for application. Among the new technologies, those for obtaining nanocrystals of classes II and IV drugs have been a promising approach. Nanocrystals can exhibit in vivo higher performance when compared to their counterparts in micronized form. Therefore, strategies to develop medicines containing Furosemide, with greater efficacy and safety, are of critical importance. In this sense, the application of technology in silico, with predictive property, contributes to the rationalization of testing in research and development of new dosage forms. The objectives, as a result, were the preparation and the physicochemical characterization of Furosemide nanocrystals, and it\'s in silico evaluation on oral and pulmonary absorption using a computational tool. The nanocrystals were obtained using a high-energy milling technology under simultaneous revolution/rotation motion. The determination of the size distribution and morphology was performed using laser diffraction and scanning electron microscopy, respectively. Furthermore, differential scanning calorimetry, differential thermogravimetry, X-ray diffraction and Low Shift Raman spectroscopy were performed to investigate possible interactions and changes in the crystalline state of the nanocrystals. To measure the increase in the equilibrium solubility and dissolution rate, the shake flask and intrinsic dissolution rate (IDR) methods were used respectively. The nanocrystals size appeared thirty times lower (231 nm) compared to the initial size (7,1 µm). The nanocrystals were stable with concern to its thermal characteristic not showing interactions between the excipients and the nanocrystals; however, they exhibited less defined crystal structure, indicating partial amorphization. The nanocrystals saturation solubility increased approximately three times. Consequently, 2.2, 1.8 and 3.8 folds increase were observed in IDR when compared to the Furosemide raw material in SGF, buffer 4.5 and SIF, respectively. The in silico nanocrystal studies revealed moderate changes in its oral absorption and pharmacokinetic profile. When the pulmonary route of administration was used, the nanocrystals showed higher performance compared to oral route administration; highlighting the increase in Fa % and Cmax and a significant decrease in Tmax. In conclusion, the technology platform obtained has potential application in the development of innovative dosage forms for Furosemide pulmonary delivery.
3

Nanocristais de furosemida: preparação, caracterização físico-química e avaliação in silico de absorção oral e pulmonar / Furosemide nanocrystals: preparation, physical-chemical characterization and in silico evaluation of oral and lung absorption

Savio Fujita Barbosa 19 August 2014 (has links)
Segundo a Organização Mundial de Saúde, a hipertensão arterial é responsável por uma crise global de saúde pública, sendo as doenças cardiovasculares implicadas em aproximadamente 17 milhões de mortes/ano, das quais, 9,4 milhões ocasionadas por complicações provocadas pela hipertensão, como edema pulmonar. Quanto ao arsenal terapêutico disponível, a furosemida, potente diurético de alça, é amplamente utilizada em situações de controle e emergência relacionadas à hipertensão e ao edema pulmonar cardiogênico. Apesar do elevado índice de sua prescrição, esse fármaco pertence à classe IV do Sistema de Classificação Biofarmacêutica (SCB), apresentando absorções intestinais erráticas e variáveis. Tais características representam desafio para o desenvolvimento de formas farmacêuticas orais. Assim, adoção de tecnologias inovadoras associadas à via de administração pulmonar pode permitir abordagem terapêutica alternativa, com elevado potencial de aplicação. Entre as tecnologias inovadoras, a obtenção de nanocristais de fármacos classes II e IV tem sido promissora. Nanocristais podem exibir desempenho in vivo superior quando comparados aos seus homólogos, na forma micronizada. Portanto, estratégias que permitam o desenvolvimento de medicamentos contendo furosemida, com maior eficácia e segurança, são de fundamental importância. Nesse sentido, a aplicação de tecnologia in silico, com propriedade preditiva, contribui para a racionalização de ensaios na pesquisa e no desenvolvimento de novas formas farmacêuticas. Objetivou-se, desse modo, a preparação e a caracterização físico-química de nanocristais de furosemida e sua avaliação in silico na absorção oral e pulmonar empregando ferramenta computacional. Os nanocristais foram obtidos por moagem à alta energia, utilizando movimentos simultâneos de revolução/rotação. A determinação da distribuição do tamanho e a morfologia foram realizadas por difração de raios laser e microscopia eletrônica de varredura, respectivamente. As possíveis interações e/ou alterações do estado cristalino do fármaco foram investigadas por calorimetria exploratória diferencial, termogravimetria diferencial, difração de raio X e espectroscopia Raman de baixo deslocamento. Quanto à solubilidade do nanocristal, foram realizados ensaios para a determinação do aumento na solubilidade de equilíbrio e da velocidade dissolução, utilizando os métodos shake flask e velocidade de dissolução intrínseca (VDI), respectivamente. A moagem à alta energia permitiu a obtenção de nanocristais com tamanho médio trinta vezes menor (231nm) do que o tamanho inicial, na escala micrométrica (7,1 µm). Os nanocristais apresentaram estabilidade térmica. Não foram observadas interações entre os excipientes e os nanocristais, que, entretanto, exibiram estrutura cristalina menos definida, o que indica parcial amorfização do nanocristal. A solubilidade de saturação dos nanocristais aumentou aproximadamente três vezes; como consequência, houve aumento na VDI em 2,2 vezes, 1,8 vezes e 3,8 vezes, quando comparado à VDI da furosemida micronizada em meio SGF, tampão 4,5 e SIF, respectivamente. Quanto às avaliações in silico dos nanocristais, sua absorção oral revelou moderada alteração no perfil farmacocinético. Quando foi utilizada a via de administração pulmonar, os nanocristais apresentaram maior desempenho quando comparada a via de administração oral; destacando-se o aumento na Fa% e na Cmáx e a acentuada diminuição no Tmáx. Em conclusão, a plataforma tecnológica obtida tem potencial aplicação no desenvolvimento de formas farmacêuticas inovadoras para administração pulmonar de furosemida. / According to the World Health Organization, hypertension is responsible for global public health crisis, being the cardiovascular diseases involved in approximately 17 million deaths a year, of these, 9.4 million occasioned by hypertension complications such as pulmonary edema. Regarding therapeutic arsenal available, Furosemide is a potent loop diuretic widely used in control and emergency situations related to hypertension and cardiogenic pulmonary edema. Despite the high level of prescribing, this drug belongs a class IV drug, according to Biopharmaceutics Classification System (BCS), exposing erratic and variable intestinal absorption. These characteristics represent a challenge for the development of oral dosage forms. Thus, adoption of innovative technologies associated with pulmonary route of administration may allow an alternative therapeutic approach, with high potential for application. Among the new technologies, those for obtaining nanocrystals of classes II and IV drugs have been a promising approach. Nanocrystals can exhibit in vivo higher performance when compared to their counterparts in micronized form. Therefore, strategies to develop medicines containing Furosemide, with greater efficacy and safety, are of critical importance. In this sense, the application of technology in silico, with predictive property, contributes to the rationalization of testing in research and development of new dosage forms. The objectives, as a result, were the preparation and the physicochemical characterization of Furosemide nanocrystals, and it\'s in silico evaluation on oral and pulmonary absorption using a computational tool. The nanocrystals were obtained using a high-energy milling technology under simultaneous revolution/rotation motion. The determination of the size distribution and morphology was performed using laser diffraction and scanning electron microscopy, respectively. Furthermore, differential scanning calorimetry, differential thermogravimetry, X-ray diffraction and Low Shift Raman spectroscopy were performed to investigate possible interactions and changes in the crystalline state of the nanocrystals. To measure the increase in the equilibrium solubility and dissolution rate, the shake flask and intrinsic dissolution rate (IDR) methods were used respectively. The nanocrystals size appeared thirty times lower (231 nm) compared to the initial size (7,1 µm). The nanocrystals were stable with concern to its thermal characteristic not showing interactions between the excipients and the nanocrystals; however, they exhibited less defined crystal structure, indicating partial amorphization. The nanocrystals saturation solubility increased approximately three times. Consequently, 2.2, 1.8 and 3.8 folds increase were observed in IDR when compared to the Furosemide raw material in SGF, buffer 4.5 and SIF, respectively. The in silico nanocrystal studies revealed moderate changes in its oral absorption and pharmacokinetic profile. When the pulmonary route of administration was used, the nanocrystals showed higher performance compared to oral route administration; highlighting the increase in Fa % and Cmax and a significant decrease in Tmax. In conclusion, the technology platform obtained has potential application in the development of innovative dosage forms for Furosemide pulmonary delivery.
4

Nanoparticle formulations of poorly water soluble drugs and their action in vivo and in vitro

Purvis, Troy Powell 01 February 2011 (has links)
Poorly water soluble drugs have been manipulated to make them more soluble, increasing the bioavailability of these drugs. Several cryogenic processes allow for production of drug nanoparticles, without mechanical stress that could cause degradation. The Ultra Rapid Freezing (URF) process is a technique which improves water solubility of drugs by reducing primary drug particle size by producing amorphous solid dispersions. Heat conduction is improved, using a cryogenic material with a high thermal conductivity relative to the solution being frozen to maintain the surface temperature and heat transfer rate while the solution is being frozen. With URF technology, the freezing rate is fixed, which drives the particle formation and determines its characteristics. Supersaturation of drug in aqueous solution can allow for better absorption of the drug via the oral and pulmonary routes. Drug formulations that supersaturate the dissolution media show the possibility for increased bioavailability from an amorphous drug form. If the concentration of drug in solution is significantly increased, higher chemical potential will lead to an increase in flux across an exposed membrane, leading to higher blood levels for an amorphous drug, compared to an identical crystalline formulation. During oral delivery, supersaturated drug concentrations would also saturate PGP efflux sites in the gut lumen, increasing the drug's bioavailability. Saturated PGP sites show zero order efflux kinetics, so increasing the drug concentration in supersaturated biological fluid will increase serum drug levels. High supersaturation levels maintained for prolonged periods would have a beneficial effect on a drug's absolute bioavailability. Pulmonary administration offers therapeutic advantages over more invasive routes of administration. Limited amount of metabolizing enzymes like CYP 3A4 in lung tissue along with avoidance of first pass metabolism are advantages to pulmonary delivery. The objective of the research presented in this dissertation is to show the versatility of nanoparticulate poorly water soluble drug formulations. Due to the reduced particle size and the URF manufacturing process, a wide range of applications can be used with these nanoparticles. Oral and pulmonary administration routes can be explored using nanoparticles, but in vitro cell culture testing can show clinical benefits from this type of processing technology. / text
5

Role of the Endocannabinoid System in Extinction of Learned Behaviours Motivated by Opioid-Induced Reward and Aversion in Rats

Manwell, Laurie 26 August 2013 (has links)
Recent evidence suggesting that the endogenous cannabinoid (ECB) system can be selectively manipulated to facilitate or impair the extinction of learned behaviours — specifically regarding drug-induced aversive memories — has important consequences for research on opiate withdrawal and abstinence. Data presented here support and expand previous findings that the ECB system has an important function in the extinction of aversively motivated behaviors and is mediated by i) an increase in available endogenous CB1 receptor agonists, primarily anandamide, and ii) the exogenous CB1 receptor agonist Δ9-THC, in a manner that is dependent upon both the dose and route of administration. Experiments demonstrated that the fatty acid amide hydrolase (FAAH) inhibitor, URB597, which blocks deactivation of endogenous CB1 ligands, such as anandamide, significantly facilitated extinction of naloxone-precipitated morphine withdrawal-induced conditioned cue aversion, whereas the CB1 receptor antagonist/inverse agonist SR141716 significantly impaired extinction. Several experiments demonstrated that neither the CB1 antagonist AM251 nor the FAAH inhibitor URB597 had any effect on extinction learning for morphine-induced conditioned cue preference. A method was developed for analysing cannabinoid levels in blood by liquid chromatography/mass spectrometry (LC/MS) to compare bioavailable levels of Δ9-THC and its primary psychoactive metabolite. Experiments were designed to meet three primary objectives: 1) to provide further support for the role of the ECB system in the extinction of aversively-motivated behaviours, 2) to compare bioavailable levels of Δ9-THC and its primary psychoactive metabolite, 11-OH-Δ9-THC, after pulmonary and parenteral administration, and 3) to demonstrate that the route of administration of Δ9-THC can have a significant impact on whether or not it facilitates or impairs extinction learning. Results showed that inhaled Δ9-THC dose- and time-dependently facilitated rates of extinction learning of the conditioned aversion whereas injected Δ9-THC significantly impaired extinction. These data suggest that the route of administration of Δ9-THC has important consequences for its resulting pharmacokinetic and behavioural effects, specifically, that pulmonary exposure facilitates, whereas parenteral exposure impairs, rates of extinction learning for conditioned cue aversion. Thus, pulmonary administration of Δ9-THC may prove more beneficial for pharmacological potentiation of extinction learning for aversive memories, such as those supporting drug-craving/seeking in opiate withdrawal-syndrome. / NSERC and OGS
6

Encapsulation de la vitamine E dans des vecteurs pharmaceutiques inhalables préparés par des contacteurs à membrane / Vitamin E encapsulation within pharmaceutical drug carriers prepared using membrane contactors

Laouini, Abdallah 03 December 2013 (has links)
L'objectif de ce travail est de développer des vecteurs pharmaceutiques, encapsulant la vitamine E, adaptés à l'administration pulmonaire par aérosolisation. La vitamine E, antioxydant physiologique, peut être utilisée pour lutter contre les phénomènes du stress oxydatif en particulier ceux observés au niveau pulmonaire. L'encapsulation de la vitamine E dans des vecteurs inhalables a été envisagée afin d'optimiser son efficacité thérapeutique en améliorant la concentration du principe actif pouvant atteindre son site d'action, les alvéoles pulmonaires. Les différents systèmes d'encapsulation de la vitamine E ont été préparés par des méthodes utilisant des contacteurs à membrane. Le principe de préparation se résume au passage de la phase dispersée, à travers les pores d'une membrane microporeuse, au sein de la phase continue. Les avantages de cette technique sont en particulier une bonne reproductibilité et un faible apport d'énergie et par conséquent un coût d'exploitation modéré. De plus, les procédés à base de contacteurs à membrane se prêtent aisément au passage à l'échelle de production industrielle. Au cours de ce travail, les paramètres influençant le procédé de fabrication par contacteur à membrane ont été étudiés ; principalement la pression transmembranaire de passage de la phase discontinue, la force de cisaillement de la phase continue et la microstructure de la membrane utilisée. Différentes configurations membranaires ont été testées telles que (i) les modules membranaires tubulaires avec écoulement tangentiel de la phase continue, (ii) les membranes planes montées dans des cellules d'agitation et (iii) les membranes dotées d'un mouvement d'oscillation à l'intérieur de la phase continue. En cas d'émulsification directe, diverses membranes ont été utilisées : des membranes SPG, des membranes microsieves et des membranes en céramique. Pour la « premix emulsification » des membranes dites dynamiques, constituées par un lit de billes en verre, ont été étudiées / The present study investigated the preparation of pharmaceutical drug carriers encapsulating the vitamin E and intended for pulmonary administration after nebulisation. Vitamin E, a physiological antioxidant, could be used to prevent cigarette smoke toxicity since several pulmonary disorders are mainly caused by oxidative stress phenomena. The methods used for the drug carriers’ preparation were based on the membrane emulsification principle. In these methods, the to-be-dispersed phase was injected in the continuous phase through the pores of a microporous membrane. The advantages of this method are: a better control over the diffusive mixing at the liquid / membrane interface and thus a fine control of droplets size distribution, a less energy consumption and an easy extrapolation of the obtained results for an industrial large scale-up. In order to investigate the preparation processes, key parameters influence on particles characteristics was investigated. Different experimental set-ups were used: (i) tubular membranes with a cross flow circulation of the continuous phase, (ii) stirred cell device with a flat micro-engineered membrane, (iii) oscillating membrane module in a stationary continuous phase. For direct emulsification, various membranes were used such as : SPG membranes, micro-engineered membranes and ceramic membranes. For premix emulsification, a packed bed of glass beads, called dynamic membrane, was studied. Four different drug carriers were developed during this study: liposomes, micelles, nano-emulsion and solid-lipid particles. The different encapsulating systems were characterized in terms of size distribution, zeta potential, microscopic morphology, encapsulation efficiency and stability. Results showed that the obtained drug carriers presented convenient properties. After nebulization of vitamin E encapsulating systems, the obtained aerosols presented satisfying aerodynamic characteristics which allowed the prediction (using a mathematical model) of a high level of vitamin E deposit on its action site

Page generated in 0.1239 seconds