A novel approach to the preparation of injectable emulsions by a spontaneous emulsification process

Abstract

Submicronic emulsions of muramyltripeptide-cholesterol (MTP-Chol), diazepam and amphotericin B were prepared using an original and simple method. This procedure is based on a spontaneous emulsification process, comprising the following steps: (1) dissolving the oil phase containing phospholipid in the alcoholic solution: (2) optionally dissolving the drug into the oily alcoholic phase and (3) mixing the product of step (2) with an aqueous preparation of surfactant, forming an oil-in-water emulsion, and finally, (4) removing at least most of any co-solvent which is present. The emulsions exhibited a mean droplet size in the range 200–300 nm. The results indicated that emulsions prepared by this method are very stable. They can also be sterilized by heat sterilisation or by filtration. In the case of MTP-Chol, the emulsion retained biological activity. Taken together, these results suggest that an emulsion obtained by spontaneous emulsification process would be very suitable for use as a drug carrier.