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La fabrication d’un médicament sous forme de comprimés à base d'une plante fraîche reste actuellement encore un véritable enjeu et ce, à cause de la variabilité qui peut exister dans les différents lots d'extraits de plantes ainsi qu’à la limite imposée par les techniques de fabrication de comprimés existantes actuellement. Différents problèmes rencontrés avec la formulation actuelle de ce type de comprimés ont été observés tels que : les propriétés physiques du comprimé (très faible dureté des comprimés et temps de désagrégation assez long), goût désagréable, grande variabilité (variabilité de l'extrait sec) et mauvaise stabilité de la substance médicamenteuse. Des observations antérieures ont indiqué que la stabilité de la substance médicamenteuse dans les comprimés d'Echinacea purpurea ainsi que le goût peuvent être améliorés en la mélangeant avec de la bêta-cyclodextrine (β-CD). Dans la thèse de doctorat, une formulation actuelle commercialisée de comprimés d’Echinacea purpurea a été réalisée par la technique de la granulation par voie humide, avec un mélangeur à cisaillement élevé. Dans la formulation, presque la totalité de l'excipient (lactose monohydraté) est mouillé par le concentré d'Echinacea purpurea. Afin de réduire la quantité d'excipients à granuler et à sécher et d’obtenir un produit avec moins cher des couts de matériaux premières, un procédé de granulation classique a été proposé où seulement une fraction de la quantité totale de charge (cellulose microcristalline (MCC)) est utilisée pour la granulation et le séchage; le reste de la charge (sorbitol) est ajouté après la granulation. Ce granulat peut servir de matériau de base des différents comprimés. Dans les différentes expérimentations réalisées, la teinture d’Echinacea purpurea a été utilisée comme modèle pour l'optimisation de la fabrication des comprimés à base de plantes. L'objectif de la thèse était par conséquent de développer une nouvelle formulation de comprimés d’Echinacea purpurea en utilisant un procédé de granulation classique. Avec une meilleure maîtrise de la granulation humide (WGP) et son influence sur les propriétés physiques des comprimés, ceux-ci doivent être optimisés du point du vue de la stabilité de l'ingrédient actif qui se présente sous forme solide (alkylamides) et des propriétés physiques des comprimés, en particulier le taux de dissolution et les propriétés physiques des comprimés. / One current formulation of Echinacea tablets which is examined in the present thesis is to produce tablets in a wet granulation process (WGP) with a high shear mixer. During the manufacturing, almost the whole amount of the excipient (lactose monohydrate) is wetted by Echinacea purpurea concentrate. In order to reduce the amount of excipients being granulated and dried by a basis granulate method was proposed where only a fraction of the total amount of filler (Microcrystalline cellulose, MCC) is used for granulation and drying, the rest of the filler (sorbitol) is added after granulation. This granulate can serve as basis material for different tablets.Purpose: in the PhD thesis, tablets containing Echinacea purpurea tincture were used as a model for the optimization of herbal tablets. The aim of the dissertation was to develop a new Echinaforce formulation based on the “Basis Granulate” technology. With deeper understanding of the WGP and its influence on the physical tablet properties, the new Echinaforce tablets should be optimized in term of cost of goods, taste of tablets, stability of the active ingredient in solid forms (alkylamides) and the physical tablet properties of Echinaforce tablets, especially the dissolution rate and the compaction properties of the final tablet.

High shear melt granulation (HSMG) is an established technology for a production of densified granules. In this project, it was used as a novel solvent-free method for the preparation of cocrystals. Cocrystals produced by HSMG were compared to those prepared by Hot Melt Extrusion (HME) to investigate the influence of variable parameters and conditions on the process of cocrystal conversion. The potential for the active control of cocrystals polymorphism utilising the intrinsic properties of lipids was also investigated in this project. Different cocrystal pairs were prepared by both cocrystallisation methods using glycol derivative polymers. Thermal analysis, powder X-ray diffraction and Raman spectroscopy were used as analytical techniques to determine the cocrystal yield and purity. The results obtained from HSMG suggest that sufficient binder concentrations (above 12.5% w/w) in a molten state and continuous shearing force are necessary to achieve a complete cocrystals conversion. Further increase in binder concentration (15% w/w) was found to provide more regular shape and smooth surface to the prepared spherical granules. Cocrystals preparation by HME was achievable after introducing a mixing zone to the extruder configuration (Conf B and Conf C) providing densified extrudates containing pure cocrystals. In conclusion, HSMG was found as a versatile technique for the preparation of pure pharmaceutical cocrystals embedded in polymer matrix within a spherical shape granule of smooth surfaces, providing additional desirable characteristics. Intensive surface interaction, enhanced by sufficient mixing under optimal parameters, was found as a key influencing factor in cocrystallisation. Cocrystals polymorphism was actively controlled by employing the intrinsic properties of polymers and lipids.

<p>Relationships between stresses during the drying process, particle structural and functional properties, and particle engineering by the drying process were addressed in this thesis. In the first part, the importance of the drying phase and the effect of the drying rate on the intragranular porosity of microcrystalline cellulose pellets were investigated. Differences in porosities of dried pellets could be explained by liquid-related differences in densification during convective drying rather than by differences in densification during wet agglomeration. An increased drying rate gave more porous pellets with a lower compression shear strength, and thereby stronger tablets. The next part dealt with modulation of solid-state stability and tabletting behaviour of amorphous lactose by incorporation of different polymers by spray drying. Increased content and molecular weight of poly(vinylpyrrolidone) (PVP) resulted in an increased resistance to crystallisation provoked by heat and moisture. The stabilising effect was even more evident after long-term storage. However, the glass transition temperature was almost unaffected and may, therefore, be questioned as a stability indicator for these types of materials. The presence of the polymers resulted in somewhat less deformable particles. Incorporation of PVP increased the compactability, whilst a surfactant decreased it, which could be shown to be related to differences in particle-particle adhesivity between the different particles. This thesis contributes to increased mechanistic understanding in the area of particle engineering that may lead to better prediction and optimisation of the functionality of pharmaceutical particles, which is of the utmost importance in the development and production of solid dosage forms.</p>

Relationships between stresses during the drying process, particle structural and functional properties, and particle engineering by the drying process were addressed in this thesis. In the first part, the importance of the drying phase and the effect of the drying rate on the intragranular porosity of microcrystalline cellulose pellets were investigated. Differences in porosities of dried pellets could be explained by liquid-related differences in densification during convective drying rather than by differences in densification during wet agglomeration. An increased drying rate gave more porous pellets with a lower compression shear strength, and thereby stronger tablets. The next part dealt with modulation of solid-state stability and tabletting behaviour of amorphous lactose by incorporation of different polymers by spray drying. Increased content and molecular weight of poly(vinylpyrrolidone) (PVP) resulted in an increased resistance to crystallisation provoked by heat and moisture. The stabilising effect was even more evident after long-term storage. However, the glass transition temperature was almost unaffected and may, therefore, be questioned as a stability indicator for these types of materials. The presence of the polymers resulted in somewhat less deformable particles. Incorporation of PVP increased the compactability, whilst a surfactant decreased it, which could be shown to be related to differences in particle-particle adhesivity between the different particles. This thesis contributes to increased mechanistic understanding in the area of particle engineering that may lead to better prediction and optimisation of the functionality of pharmaceutical particles, which is of the utmost importance in the development and production of solid dosage forms.