SOLID-STATE CHARACTERIZATION OF A DRY EMULSION - A POTENTIAL-DRUG DELIVERY SYSTEM

Dry emulsions were prepared by spray drying liquid emulsions in a labo ratory spray dryer. Lactose alone, and lactose in combination with mal todextrine, was used as a water soluble, solid carrier. Sodium caseina te was used as emulsifying agent and griseofulvin was used as an oil s oluble model drug substance in very low concentration. Different fats were applied; soybean oil (liquid), hardened coconut oil (semisolid) a nd hardened rapeseed oil, being solid at room temperature. The surface of the powder particles was mainly made up of sodium caseinate, while the core was made up of fat dispersed in a carrier matrix of amorphou s lactose. Amorphous lactose is very sensitive to moisture, and during moisture uptake recrystallisation of lactose takes place and the phys ical structure of the powder particle was changed. By addition of malt odextrine as carrier, the physical structure of the spray dried powder s was tried to be maintained during recrystallisation of lactose. Reco nstitution properties of the spray dried powders were investigated and correlated to solid state characterisation of the powders performed b y Scanning Electron Microscope (SEM), Differential Scanning Calorimetr y (DSC), X-ray powder diffraction and Electron Spectroscopy for Chemic al Analysis (ESCA). (C) 1998 Elsevier Science B.V. All rights reserved .