Detection of low levels of amorphous materials using H/D exchange, FT-Raman and FT-Infrared spectroscopy

Water in oil emulsions (W/O) are good candidates as liquid delivery systems to encapsulate hydrophilic drugs: When contacted with a biological fluid, the oil phase of the emulsion behaves as a liquid membrane which separates two aqueous compartments. The use of W/O emulsions as delivery systems through IM or SC routes is currently limited for stability, viscosity or safety reasons. The use of safe oils compositions from the Montanide® range, which are widely used today in veterinary or human injectable vaccines, can solve safety and stability problems to formulate drug containing injectable emulsions. However, the proportion of internal aqueous phase in Montanide based emulsions is still limited to less than about 50%, in order to get fluid injectable emulsions. A new type of compositions, “Gel-and-Water-in-oil“ (GWO) has been now developed. It allows obtaining fluid and stable emulsions containing up to 80% of aqueous phase surrounded by an oily Montanide® layer. This study describes the manufacturing process of GWO emulsions and the influence of some composition parameters on the characteristics of this new type of emulsions. The in-vitro release of a model drug is also described. Finally, the study emphasizes the benefit which can be obtained with GWO compared to standard W/O emulsions.