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Thermal behaviour of a multicomponent solvent pharmaceutical hydrate during vacuum contact drying

1999; Elsevier BV; Volume: 38; Issue: 8 Linguagem: Francês

10.1016/s1290-0729(99)80062-3

1778-4166

S. Laurent, Joachim Allouche, Fre ́de ́ric Couture, M. Roques,

Thermodynamic properties of mixtures

A pharmaceutical drug is industrially dried with a vacuum drying process for which the energy is supplied by contact. This product is wetted with a multicomponent solvent i.e. a solvent for which components are miscible. Moreover, two hydration states exist for this drug (tetrahydrate and monohydrate). These singularities induce a different thermal behaviour from the one of porous media described in literature. The local analysis of temperature kinetics allows us to define accurately the operation progress. The free solvent vaporisation stage of the process does not result in a classical temperature plateau on account of a selective removing of one component. On the contrary, the change of hydration state (tetrahydrate to monohydrate) results in a new temperature plateau. Une substance pharmaceutique est industriellement se´che´e par un proce´de´sous vide, avec un apporte´nerge´tique effectue´par contact. Ce produit est impre´gne´d'un solvant multiconstituant, i.e. un solvant dont les composants sont miscibles. En outre, il pre´sente deuxe´tats d'hydratation (te´trahydrate et monohydrate). Ces singularite´s se traduisent par un comportement thermique sensiblement diffe´rent du comportement des millieux poreux de´crits dans la litte´rature. L'analyse locale des cine´tiques de tempe´rature permet de de´finir pre´cise´ment le de´roulement de l'ope´ration. La phase de vaporisation du solvant libre ne correspond pas au plateau classique de tempe´rature, en raison de l'e´limination se´lective de l'un des constituants. En revanche, le changement d'e´tat d'hydratation impose un nouveau palier en tempe´rature.