Alloys with good toughness and elevated temperature properties like A201 are expensive and can be more difficult to process. This results in the use of heavier but less expensive alternatives in many applications where toughness is of concern, such as steels. Common alloys such as A356 and E357 are relatively cheap and easy to work with. However, these alloys have considerably lower toughness than premium alloys. This research aims to investigate surface modification treatments that could yield better toughness at a low cost in a common aluminum alloy. The process must show significant improvement in said properties, be cost effective, and easily adaptable in a common foundry. Diffusion of coating material into the substrate was investigated with a variety of coating metals. The diffusion process was facilitated in the solutionizing step for the given substrate aluminum in order to strengthen the sub-surface region of the parts. This research aims to provide a platform for further research into the practical effects of the coating and tempering on impact and toughness properties. These samples were characterized by optical and scanning electron microscopy, EDS, impact testing, and tensile testing.

Introdução e objetivos: As nanocápsulas, uma vez que são produzidas com polímeros, representam sistemas mucoadesivos promissores. O uso desse tipo de sistema é importante no delineamento de medicamentos que vislumbrem a membrana sublingual como via de administração, devido ao constante fluxo de saliva. Em vista disso, esse trabalho tem como objetivos: estudar o efeito da nanoestruturação em nanocápsulas de polímeros de diferentes características iônicas, quanto as suas propriedades mucoadesivas, quando veiculadas em suspensão, hidrogel ou pós, e frente a distintas superfícies mucoadesivas (discos de mucina, mucosa vaginal ou mucosa bucal); desenvolver nanocápsulas contendo carvedilol, avaliando as suas propriedades mucoadesivas e perfil de permeação do fármaco em diferentes modelos de membrana sublingual; e produzir, a partir das nanocápsulas secas, comprimidos sublinguais contendo carvedilol nanoencapsulado. Metodologia: Nanocápsulas formadas por Eudragit® RS100, Eudragit® S100 ou poly(ε-caprolactona) [PCL] foram produzidas pelo método de deposição interfacial do polímero. Suas propriedades mucoadesivas foram avaliadas empregando analisador de textura. As nanocápsulas contendo carvedilol foram produzidas pelo mesmo método citado acima, utilizando Eudragit® RS100 e a PCL. A mucoadesão dessas nanocápsulas foi avaliada quanto a sua interação com moléculas de mucina, além do efeito da sua interação com a mucosa sublingual de porco na permanência do fármaco sobre a mucosa e na sua permeação, em presença de um fluxo salivar mimetizado. O transporte de carvedilol através de uma monocamada celular de células de epitélio oral (SCC4) também foi estudado. As suspensões de nanocápsulas foram, então, secas por aspersão e as propriedades das nanocápsulas redispersas foram reavaliadas. Na última etapa, foram produzidos comprimidos sublinguais pelo método de compressão direta, a partir dos pós desenvolvidos. Resultados: A mucoadesividade dos polímeros Eudragit® RS100, Eudragit® S100 e PCL foi potencializada pela sua estruturação em nanocápsulas. Dentre as formulações analisadas, as nanocápsulas catiônicas, formadas por Eudragit® RS100, veiculadas em gel, foram as que apresentaram melhores propriedades adesivas. Além disso, o processo de secagem não interferiu na adesividade das nanocápsulas originais. Em relação a superfície utilizada, a mucina se mostrou uma superfície mais adesiva comparada as mucosas suínas. Entretanto, a mucina reproduziu as diferenças observadas entre as formulações. As nanocápsulas contendo carvedilol interagiram bem com moléculas de mucina, sendo essa interação mais intensa para as nanocápsulas catiônicas [Eudragit® RS100], que para as aniônicas [PCL]. No entanto, ambas as nanocápsulas melhoraram o contato do carvedilol com a mucosa sublingual suína, o que fez com que mais fármaco permeasse através da mucosa, na presença de um fluxo salivar mimetizado, em comparação com uma solução do fármaco. Além disso, as nanocápsulas controlaram a permeação do fármaco através de mucosa sublingual de porco, bem como através de monocamadas de células SCC4. A partir destes resultados, as suspensões de nanocápsulas foram secas por aspersão. As nanopartículas foram recuperadas após redispersão aquosa dos pós e mantiveram suas propriedades mucoadesivas e biofarmacêuticas. Na sequência, os comprimidos foram produzidos como forma farmacêutica final. A presença de nanoestruturas foi observada nos comprimidos, as quais foram liberadas após total desintegração destes em saliva artificial. Além disso, a liberação do fármaco partir dos comprimidos contendo as nanocápsulas apresentou um perfil controlado comparado aos comprimidos contendo o fármaco livre, reforçando a manutenção da estrutura supramolecular das nanocápsulas nos comprimidos. Conclusão: As nanocápsulas produzidas com Eudragit® RS100, Eudragit® S100 ou PCL apresentaram boas características mucoadesivas. As, nanocápsulas de Eudragit® RS100 e PCL também melhoraram a interação do carvedilol com a membrana sublingual de porco. Em ambos os estudos, um melhor desempenho mucoadesivo foi observado para as nanocápsulas catiônicas. Além disso, o carvedilol apresentou boa permeação através de mucosa sublingual suína e através de monocama celular de células de epitélio oral. Ainda, a secagem por aspersão das suspensões de nanocápsulas não alterou significativamente as suas propriedades. A compressão direta dos pós secos por aspersão produziu comprimidos inovadores contendo um sistema nanotecnológico mucoadesivo para administração sublingual de carvedilol, como um nanomedicamento. / Introduction and objectives: Nanocapsules may represent promissing mucoadhesive systems since they are produced with polymers. The use of these systems is very important for drug administration by the sublingual route due to the constantly salivary flux in the oral cavity. In view of this, the objectives of this study were: to study the effect of the nanostructuration in nanocapsules on the mucoadhesiveness of polymers with different charge surface and the effect of the vehicle (suspension, hydrogel, and powder) on the mucoadhesiveness of nanocapsules as well as the effect of different mucosal surfaces (mucin, vaginal mucosa, and buccal mucosa); to develop carvedilol-loaded nanocapsules and to evaluate their mucoadhesive properties and drug permeation profiles using different models of sublingual membrane; and to produce sublingual tablets using spray-dried carvedilol-loaded nanocapsules. Methods: Eudragit®RS100, Eudragit®S100 or poly(ε-caprolactone) [PCL] nanocapsules were produced by interfacial deposition of the polymer method. Their mucoadhesiveness were evaluated by tensile stress tester. Carvedilol-loaded nanocapsules were produced by the method cited above and using Eudragit® RS100 or PCL as polymers. Mucoadhesiveness of nanocapsules were studied analyzing their interaction with mucin molecules and analyzing the effect of their interaction with porcine sublingual mucosa on drug retention as well on the amount of drug permeated to the receptor fluid in the presence of simulated salivary flux. The transport of carvedilol across monolayers of oral epithelial cells (SCC4) was also evaluated. In the next step, nanocapsules suspensions were spray-dried and the properties of redispersed nanocapsules were evaluated. In the last step, sublingual tablets were produced by direct compression using the spray-dried nanocapsules. Results: Mucoadhesiveness of Eudragit® RS100, Eudragit® S100 and PCL were improved by their structuration in nanocapsules. Among the tested formulations, the cationic Eudragit® RS100 nanocapsules formulated as a hydrogel showed the best behavior. Moreover, the drying process did not interfer in the adhesiveness of original nanocapsules. Regarding the surface substrate, mucin discs were more adhesive than porcine mucosas. However, mucin was able to reproduce the differences observed between the formulations. Carvedilol-loaded nanocapsules interacted with mucin molecules and this interaction was more intense for cationic Eudragit® RS100 nanocapsules than for anionic PCL nanocapsules. However, both nanocapsules increased the amount of drug retained on porcine sublingual mucosa and improved the amount of drug permeated through mucosa, in comparison to the drug solution, in presence of a mimetic salivary flux was present. Furthermore, nanocapsules were able to control the drug permeation across porcine sublingual and through SCC4 monolayer. Subsequently, suitable powders were obtained by spray-drying. The original nanoparticles were recovered after aqueous redispersion of powders and the maintenance of their mucoadhesiveness and biopharmaceutics properties was observed. Moreover, sublingual tablets were produced as a final pharmaceutical form. The presence of nanometric particles in the tablets was observed and they were released after tablet disintegration in artififcial saliva. The drug was released by a controlled way from tablets containing nanocapsules when compared to tablets containing the non-encapsulated drug, reinforcing the maintenance of supramolecular structure of nanocapsules in the tablets. Conclusion: The Eudragit® RS100, Eudragit® S100 and PCL nanocapsules showed good mucoadhesive characteristics. Moreover, Eudragit® RS100 and PCL nanocapsules improved the carvedilol interaction with porcine sublingual mucosa. In both studies, cationic nanocapsules showed the best mucoadhesive performance. Additionally, carvedilol showed a good permeation across porcine sublingual mucosa and through oral epithelial cells monolayer. The spray-drying process did not change the properties of the original aqueous nanocapsules. Furthermore, their direct compression produced innovative tablets containing a mucoadhesive nanotechnological system for sublingual administration of carvedilol as a nanomedicine.

Monascus é um fungo ascomiceto tradicionalmente utilizado na China. Os povos orientais utilizam o produto de sua fermentação em arroz não aglutinado, ao qual dão o nome de \"Ang-kak\", e no inglês, \"Red yeast rice\". Sabe-se que este extrato contém substâncias hipocolesterolêmicas, como a Monacolina K, inibidor competitivo da enzima HMG-CoA. Este trabalho se insere neste contexto uma vez que consiste na otimização da fermentação e secagem do extrato de Monascus ruber. Embora já existam estudos sobre a atividade biológica deste extrato, os quais comprovam seus benefícios, não há muitos estudos que visam otimizar a sua fermentação em meio submerso e a secagem do extrato. Para tanto, foram avaliados diversos parâmetros na fermentação através de dois planejamentos fatoriais. No primeiro planejamento, as variáveis estudadas foram o meio de cultura (meio arrozina-glicose e meio sólido de arroz) e agitação (0 rpm e 10 rpm). A agitação promoveu um leve aumento na produção de monacolina-K, já o meio líquido foi mais eficiente na produção desta substância do que o meio sólido de arroz. Baseado neste experimento escolheu-se o meio fermentativo para os demais estudos. No segundo experimento as variáveis estudadas foram a adição no meio arrozina-glicose de zinco, amônio e glutamato. Neste experimento pôde-se verificar que o a produção de monacolina K e de pigmentos foi maior no meio com concentrações intermediárias de zinco e de glutamato e com concentrações maiores de amônio. No estudo da secagem, realizou-se um planejamento Box Benkhin, a fim de se avaliar a influência da proporção do adjuvante: fármaco, do tempo de incorporação do excipiente e da temperatura sobre características do extrato seco como: densidade aparente, densidade de compactação, fator de Hausner, umidade residual, atividade de água, atividade antioxidante e teor de monacolina K. Em relação à proporção do adjuvante: droga pode-se afirmar que a menor produz pós com menor atividade de água e teor de umidade, porém todos os pós obtidos tiveram seu teor de umidade e atividade de água dentro do ideal e a análise estatística mostrou que a proporção do adjuvante: droga não influenciou de forma significativa a atividade de água e o teor de umidade; a proporção 7,5:1 produz melhor rendimento e pós com melhores propriedades de fluxo, por possuírem menores valores de índice de compressibilidade e fator de hausner, já com a proporção 10:1 fornece pós com maior teor de monacolina e maior atividade antioxidante. Em relação à temperatura pode-se afirmar que utilizando-se 50°C obteve-se pós com melhores propriedades de fluxo, ou seja, menor índice de compressibilidade e menor e fator de hausner. Utilizando temperatura de 80°C obteve-se menor atividade antioxidante, maior rendimento e maior teor de monacolina K. Contudo, a análise estatística mostrou que a temperatura não influenciou de forma significativa o teor de monacolina K. Com uma temperatura maior, 110°C obteve-se menor teor de umidade e maior teor de pigmentos vermelhos. Em relação ao tempo de mistura do adjuvante pode-se afirmar que com 1 minuto obteve-se maior teor de pigmentos e pós com melhores propriedades de fluxo, com 5 minutos obteve-se menor teor de pigmentos, maior rendimento, maior teor de monacolina K e menor atividade de água, já com 10 minutos obteve-se menor teor de umidade e maior porcentagem de inibição. A análise estatística demonstrou que o tempo de mistura não influencia de forma significativa a atividade antioxidante. / Monascus ruber is an ascomycete fungus traditionally used in China. Eastern peoples use the product of its fermentation in rice non-agglutinated, which they call Ang-kak (red yeast rice, in English). It is known that this extract contains hypocholesterolemic substances such as the Monacoline K, a competitive inhibitor of the HMG-CoA enzyme. This work comes into this context since it consists in the optimization of the fermentative and drying processes of the Monascus rubers extract. Despite the existence of studies on the biological activity of this extract, which support its benefits, not many aimed at optimizing the fermentative process in submerged conditions and the drying of the extract. This work aimed at optimizing the fermentative process and the drying of the Monascus rubers extract. In order to do such, several parameters of the fermentative process were evaluated through two factorial plannings. In the first one, the variables studied were the modes of culture (liquid culture and solid-state culture) and agitation (0 rpm and 10 rpm). Agitation led to a slight increase in the production of Monacoline-K, and the liquid culture was more efficient in the production of this substance than the solid-state culture. Based on these findings, the fermentative substrate for the following experiments was chosen. In the second experiment, the variables studied were the addition of zinc, ammonium and glutamate in the liquid culture. It was observed that the production of monacoline-k and pigments was increased in the substrates with intermediary concentrations of zinc and glutamate and higher concentration of ammonium. In the drying study, a Box-Benkhin planning was adopted in order to assess the influence of the adjuvant: drug proportion, excipient incorporation time and temperature over the characteristics of the dried extract, such as: apparent density, compactation density, Hausner factor, residual humidity, water activity, antioxidant activity and monacoline-K levels. Regarding the adjuvant: drug proportion, it can be stated that the 5:1 proportion produces powders with smaller water activity and humidity levels, however, all the powders obtained presented humidity levels and water activity within the ideal and, besides that, the statistical analysis showed that the adjuvant: drug proportion had no significant influence on water activity or humidity levels; the proportion of 7,5:1 produces greater quantities and powders with better flow properties, since they have lower values of IC and FH; and with the proportion of 10:1, powders with higher levels of monacoline-K and greater antioxidant activity can be obtained. Concerning temperature, it was observed that powders with better flow properties (lower IC and FH) were obtained at 50°C. At 80°C, lower antioxidant activity, greater quantities and higher levels of monacoline-K were observed, however, the statistical analysis showed that the temperature had no significant effect on the levels of monacoline-K. With a higher temperature (110°C), lower humidity levels and higher red pigment levels were obtained. Concerning the mix time adjuvant: drug proportion, it can be stated that with 1 minute higher levels of pigment and powders with better flow properties were obtained; lower levels of pigment, greater quantities, higher levels of monacoline-K and lower water activity were obtained with 5 minutes and; lower humidity level and greater percentage of inhibition were observed with 10 minutes, however, the statistical analysis showed that the mix time has no significant influence on the antioxidant activity.

Crystal engineering study using spray dryer was performed for scale-up and rapid, continuous crystallisation of co-crystals from solution. The study emphasise on developing co-crystals of two structurally similar compounds, caffeine (CAF) and theophylline (THEO) with various di-carboxylic acids. The incongruently soluble pair of CAF and THEO with di-carboxylic acids acquires large solubility difference which is important to consider for its utility in product development. Based on previous assumption that maleic acid (MAL) elevates CAF’s solubility; solubility of the two similar compounds was tested in various dicarboxylic acids. Other solubility enhancement strategies such as introduction of surfactant and binary solvents were also scrutinised. A kinetically similar bench-scale technique, rotary evaporator (rotavap) was investigated as a pre-screening tool for the production of co-crystals via spray drying. Furthermore, various process parameters within the spray dryer were optimised to control the kinetic conditions which influence co-crystallisation and quality of the product. Another polymorphic co-crystal pair, CBZ (carbamazepine) and SAC (saccharin) was examined in various solvents and its degradation was evaluated over a period of few months. In this study, a two-step conversion of CBZ into its degradate was hypothesised. Rotavap delivered a true reflection of co-crystal favoured via spray drying apart from co-crystal pairs depicting polymorphism. Spray dryer offered a unique environment favouring metastable forms of co-crystals irrespective of the starting component stoichiometry; generating CAF:MAL 2:1. However, due to process limitation and solubility constraint, the impurity of CAF in CAF:MAL 2:1 co-crystals could not be abolished.

Resumo: O objetivo desta pesquisa foi identificar a cobertura mínima necessária ao controle do ácaro Brevipalpus phoenicis. O trabalho foi conduzido no Depto. Fitossanidade - UNESP, Jaboticabal, em frutos de laranja infestados artificialmente com ácaros criados em câmara climatizada. Testou-se o efeito residual e tópico de propargite e verificou-se que o acaricida possui ambos os efeitos. Investigou-se o efeito da cobertura de frutos com pulverização da calda dos acaricidas: cyhexatin, óxido de fenbutatina, dinocap e propargite na concentração comercial e metade desta. Verificaram-se efeitos diferenciados, sendo a maior eficiência verificada para o cyhexatin e a maior migração dos ácaros da área tratada para o óxido de fenbutatina. Neste ensaio foi confirmado que quanto maior a área do fruto tratada maior a mortalidade dos ácaros. Determinou-se, então a cobertura mínima com base no tamanho e número de gotas a ser depositada para obtenção de controle satisfatório do ácaro. Utilizou-se o acaricida propargite nas concentrações de 0,036%, 0,072%, com e sem espalhante-adesionante e 0,144% sem espalhante-adesionante. Verificou-se que a adição do espalhante-adesionante prejudicou o efeito acaricida da calda. A cobertura mínima necessária para o controle do ácaro com a calda de propargite a 0,072% determinada no trabalho, foi resultante de 18 gotas de 293 æm por centímetro quadrado. / Abstract: The aim of this research work was to identify the minimum adequate spray coverage number and size to control the mite Brevipalpus phoenicis. The research was conducted at Department of Crop Protection - UNESP, Jaboticabal, using oranges artificially infested by mites reared in a controlled chamber. Residual and topical actions of propargite were tested and it was observed that the mitecide has both of effects. Effects of fruit coverage with spray of mitecides: cyhexatin, fenbutatin oxide, dinocap and propargite were investigated using the commercially recommended dosage rate and half of this dosage. It was verified that the effects varied being cyhexatin the most effective and fenbutatin oxide causing more escape of mites from treated area. In this trial was confirmed that larger the sprayed area higher was the mortality of mites. Minimum effective coverage was studied using 0.036% and 0.072% propargite solution, with and without spreader-sticker and 0.144% without the spreader-sticker. It was verified that addition of the spreader-sticker had detrimental effect on mitecide action. The minimum spray coverage to achieve control of the mite using 0.072% propargite solution determined in this work is 18 droplets of 293 æm per square centimeter. / Orientador: Tomassa Matuo / Coorientador: Carlos Amadeu Leite Oliveira / Banca: Hamilton Humberto Ramos / Banca: Casimiro Dias Gadanha Júnior / Banca: Ulisses Rocha Antuniassi / Banca: Carlos Gilberto Raetano / Doutor

Enteric pathogens form a large part of infectious diseases which contribute to a bulk of the healthcare costs. Enteric infections are usually contracted via the faecal-oral route or through contact with contaminated surfaces. Treatment by antibiotics is becoming increasingly ineffective due to the growing number of antibiotic resistant strains. Anti-microbial resistance poses a serious threat to the future of healthcare worldwide and necessitates the search for alternate forms of therapy. Bacteriophages (phages), are viruses which specifically infect and lyse bacteria. To introduce phages as a viable form of therapy, route of administration needs to be considered carefully. Model phages with broad host ranges are ideal for therapy however oral delivery to the lower gastro-intestinal (GI) poses several challenges. The acidic stomach environment can be detrimental to phages, rendering them inactive during passage. To overcome this challenge and improve the stability of phage during encapsulation and storage, this PhD research has been conducted. pH responsive polymers, Eudragit and alginate were used to develop composite microparticles which protected phage from acidic pH (pH 1-3). A novel method of acidifying oil was developed for crosslinking droplets in vitro to avoid the use of harsh solvent systems that can cause phage inactivation. Platform microfluidic technology was employed for phage encapsulation for the first time. Monodispersed droplets and particles were produced, offering fine-tuning of droplet diameter to tailor the release and pH protection of encapsulated phage. Process scale-up was attempted using membrane emulsification (ME) to produce larger volumes of encapsulated phage. In vitro and in-situ models investigated the efficacy of encapsulated phage-bacterial killing. Industrial scale method of spray drying, and electrospinning were also used to demonstrate the versatility of the formulation. Tableting dry powder phage, showed an effective method for producing solid dosage forms for therapy. Additionally, electrospun phage fibres also showed the potential use of pH responsive formulations in addressing wound infections. Improvement in encapsulated phage storage stability was observed with the addition of trehalose in the formulation. This research underpins the need for testing phage encapsulation for site-specific delivery and offers insight into the potential use of commercially available technologies.

Thesis (M. A. Agricultural Management (Horticulture)) -- University of Limpopo, 2003 / Refer to document

Tissue sealants of a liquid based formulation are widely studied in biomedical research with many starting to gain FDA approval. To date, little investigation has been put toward methods of application for tissue sealant materials, more specifically a powder based formulation. The focus of this research was to develop and prototype a powder spray device capable of administering powder based formulations with a long-term goal of integrating the device within the clinical setting. Powders can be administered in a variety of dry forms. These forms can range from non-homogenous nanoscale particles to homogeneous micro and nano-scale spheres. Incorporation of therapeutics within the powder makes this method of application favorable for the prevention or maintenance of disease. Pneumatic conveying is the transport of granulated solids using gas and is the principal basis from which the powder spray gun was designed. Fluidization aids were added to the device in order to increase powder flow properties. Analysis of spray field, spray rate, characterization of powder and ex-vivo testing was performed. All results suggest that the powder spray device is applicable for the deposition of powder based tissue sealants in a clinical setting.

Face au manque de médicaments spécifiquement conçus et mis au point pour répondre aux besoins thérapeutiques de la population pédiatrique, les autorités nationales et européennes se sont vues dans l’obligation d’établir un cadre réglementaire visant à encourager le développement de médicaments à usage pédiatrique. Un médicament destiné à l’enfant nécessite une présentation galénique spécifique et adaptée à son âge, pour permettre une administration simple et sûre. L’Académie nationale de Pharmacie a également travaillé sur le sujet et élaboré un rapport en juin 2005 avec certaines propositions notamment favoriser les formes orales solides dispersibles ou orodispersibles. Cependant, les formes orales solides posent le problème de l’acceptabilité et de l’évaluation de la palatabilité, condition requise qui représente un véritable défi. L’objectif de ce travail était (i) de développer des techniques de masquage du goût d’un principe actif modèle, l'acétaminophène, (ii) de mettre au point des méthodes d’évaluation du masquage de goût et de caractérisation des particules obtenues et, (iii) d'élaborer un procédé de fabrication d’une forme dispersible : des minigranules à désintégration rapide. Le caséinate de sodium et la lécithine, excipients potentiellement tolérables et sans danger pour un usage pédiatrique, ont été utilisés pour encapsuler le principe actif par atomisation-séchage. Le masquage de goût est évalué in vitro de façon indirecte par des études de libération du principe actif. Nous avons développé une méthode simple avec une pompe à seringues qui utilise de faibles volumes et débits de tampon et simule le flux salivaire. La méthode d’évaluation de masquage de goût développée donne des résultats en accord avec ceux d’autres méthodes existantes comme la langue électronique. La caractérisation des particules obtenues, notamment grâce à la spectroscopie par Rayons X qui permet d’obtenir une cartographie de la composition à la surface des particules enrobées, a montré une différence de composition en fonction du ratio caséinate de sodium/lécithine utilisé lors de l’atomisation. Cette différence a pu être mise en relation avec l'efficacité de masquage de goût. Une étude a ensuite été menée pour évaluer l'effet des paramètres du procédé et de la formulation sur l'efficacité de masquage de goût. Un plan factoriel complet a permis de déterminer les variables les plus importantes influant sur la quantité de principe actif libéré durant les premières minutes, soit la quantité de caséinate de sodium et de lécithine. L’optimisation par la méthode du simplex a permis d’obtenir une formulation optimisée pour laquelle la quantité libérée était 7 fois inférieure à celle du principe actif initial durant les deux premières minutes de l’essai de libération. Une autre approche visant à améliorer l'effet de masquage de goût incluait l'utilisation de caséinate de calcium à la place de caséinate de sodium. Le caséinate de calcium a été montré capable de retarder la libération du principe actif de façon plus importante lors de son association avec de la lécithine, ce qui améliore le masquage de goût. En effet, le masquage de goût est obtenu quand sur une courte période de temps (1 à 2 minutes), soit le principe actif n’est pas détecté, soit la quantité détectée est sous le seuil de perception du patient. Une forme galénique multiparticulaire à base de minigranules à désintégration rapide a ensuite été élaborée par extrusion-sphéronisation suivie d’une lyophilisation. Les minigranules présentent des qualités appropriées à savoir, une bonne sphéricité, une faible friabilité, la capacité d’incorporer une quantité élevée de principe actif et de plus, ces minigranules sont presque immédiatement désintégrés en présence d'eau lors de la mesure du temps de désagrégation avec l'analyseur de texture. Ce type de minigranules promet une forme galénique adaptée à la population pédiatrique grâce à la facilité d’administration et la flexibilité de dosage. / The development of paediatric formulations involves an urgent need but also presents many difficulties, e.g. the safety data of existing and new excipients in children stay restrictive; the development of palatable formulations for better compliance is requisite and challenging; the appropriateness of dosage form faces to dysphagia issue and flexibility of dosing for a large range of age. The aim of this work was (i) to develop a taste-masking formulation of a model drug (acetaminophen) on the one hand, and (ii) to elaborate a process for manufacture of fast disintegrating minigranules on the other hand. Sodium caseinate and lecithin, potentially tolerable and safe excipients for paediatric use, were utilized in order to encapsulate the drug through spray-drying. Taste-masking effect was demonstrated by in vitro drug release study and electronic tongue analysis. The characterization of spray-dried particles showed a difference in the surface composition according to the sodium caseinate/lecithin ratio, which related to the taste-masking efficiency. A study was subsequently undertaken to evaluate the effect of process and formulation parameters on the taste-masking efficiency. A full factorial design allowed screening for the most important variables that affect the released amount of drug during the early minutes, i.e. quantity of sodium caseinate and lecithin. An optimized formulation was successfully achieved by simplex design that released the drug 7-fold less than the unmasked drug during the first two minutes. Another approach to improve the taste-masking effect included the use of calcium caseinate rather than sodium caseinate. Calcium caseinate was showed to be more effective in delaying the drug release to a higher extent in association with lecithin. Indeed, the lower the released amount, the better the taste-masking. A multiparticulate dosage form of fast disintegration was developed through extrusion-spheronization followed by freeze-drying. The pellets exhibited suitable quality, e.g. good sphericity, low friability, ability of high drug loading, and moreover, almost immediately disintegrated in contact with water during measurement of disintegration by texture analyzer. This type of pellets promises age-appropriate dosage form for pediatric population thank to facility of administration and flexibility of dosing.

Pyruvate is a valuable chemical intermediate in the production of fine chemicals used by agrochemical, pharmaceutical, and food industries. Current technology for production of pyruvic acid is based on conversion from tartaric acid and results in environmentally incompatible byproducts. An enzymatic approach to making pyruvate was developed by cloning the glycolate oxidase (GO) gene from spinach into Pichia pastoris (Payne, et al., (1995). High-level production of spinach glycolate oxidase in the methylotrophic yeast Pichia pastoris: Engineering a biocatalyst. Gene, 167(1-2), 215-219). GO is a flavoprotein (FMN dependent) which catalyzes the conversion of lactate to pyruvate with the equimolar production of hydrogen peroxide. Hydrogen peroxide can lower GO activity and make non-catalytic byproducts, so catalase was also cloned into P. pastoris to create a double transformant. Process development work was completed at the University of Iowa's Center for Biocatalysis and Bioprocessing. High-density P. pastoris fermentation (7.2 kg cells/L) was completed at the 100 L scale. Critical fermentation set-points were confirmed at 14 h glycerol feeding followed by methanol induction at 2 - 10 g/L for 30 h. After fermentation, these cells were permeabilized with benzalkonium chloride (BAC) to enable whole-cell biocatalysis and increase enzyme activity, yielding 100 U/g for GO. In 30 L enzyme reactions, permeabilized cells were recycled three times for over 92% conversion of 0.5 M lactate with an "enzyme to product" ratio of approximately 1:2 (Gough, et al., (2005). Production of pyruvate from lactate using recombinant Pichia pastoris cells as catalyst. Process Biochemistry, 40(8), 2597-2601). Though effective, the post-fermentation process for GO recovery involved several unit-operations, including multiple washing steps to remove residual BAC. The present work has focused on minimizing unit-operations by spray-drying the fermentation product to create a powdered biocatalyst. Optimal spray-drying conditions for the Buchi B-190 instrument were 150°C drying air, 15 mL/min liquid feed rate, and 600 mg cells/mL liquid feed. These conditions resulted in P. pastoris biocatalyst with activities of 80 - 100 U/g for GO and 180,000 - 220,000 U/g for catalase. The spray-dried cells retained nearly 100% of the enzyme activity compared to BAC treated cells as reported by Gough et al. Additionally, the spray-dried biocatalyst was stable at room temperature for 30 days, and no measurable enzyme leaching was observed. Then, P. pastoris was spray-dried under optimal conditions and tested for conversion of lactate to pyruvate for an improved "enzyme to product" ratio. Enzyme reaction optimization was done at the one-liter scale in DASGIP reactors. The DASGIP system contained four parallel reactors with control of temperature, pH, and dissolved oxygen. Other key variables included substrate loading, conducting the reaction in buffer or water, minimizing enzyme concentration, and maximizing the number of enzyme recycles. Optimal performance was achieved in water at pH 7.0 with an operating temperature of 25°C and 1.0 M substrate loading. Enzyme loading was at 12 g/L for the first two cycles, and subsequently, 2 - 3 g/L of fresh cells were added every alternate cycle to reach 15 cycles. Under these conditions, 75 - 95% conversion of lactate to pyruvate was accomplished for every 12 - 16 h reaction cycle. Based on these parameters, an "enzyme to product" ratio of 1:41 was achieved.