Dissolution of cholesterol–calcium bilirubinate compressed discs by microemulsions

Abstract

The purpose of the present work was to characterize the composition and the structure of a monophasic solution able to dissolve cholesterol–calcium bilirubinate compressed discs simulating cholesterol and pigment biliary stones. Thermodynamically stable microemulsions composed of methyl tert-butyl ether, sodium dodecyl sulfate, n-butanol, and of an aqueous ethylenediaminetetraacetate solution were investigated. Their structure was defined by viscosity and conductivity measurements. The kinetics of compressed disc dissolution served to determine the optimal composition of the mixtures for rapid dissolution of the two types of discs. All the experimental results show that cholesterol and calcium bilirubinate dissolutions occur simultaneously and that the more efficient microemulsions are those exhibiting a bicontinuous structure. Dissolution de pastilles de choleste′rol–bilirubinate de calcium par des microe′mulsions. Cette e′tude a pour objet de de′finir la composition et la structure d'une solution monophasique capable de dissoudre des pastilles de choleste′rol et de bilirubinate de calcium simulant les calculs biliaires choleste′roliques et pigmentaires humains. Des microe′mulsions thermodynamiquement stables compose′es de me′thyl tertio-butyl e′ther, de dode′cylsulfate de sodium, de n-butanol et d'une solution aqueuse d'e′thylène diamine te′traace′tate ont e′te′ e′tudie′es. Leur structure a e′te′ caracte′rise′e par des mesures de viscosite′ et de conductivite′. L'e′tude cine′tique de la dissolution des pastilles place′es au contact de ces microe′mulsions montre que les dissolutions du choleste′rol et du bilirubinate se font simultane′ment et que les meilleures performances sont obtenues avec des microe′mulsions à structure bicontinue.