PREPARATION AND CHARACTERIZATION OF A PEPTIDE-CONTAINING W/O EMULSION

Human insulin as a model peptide drug was incorporated into a water-in-oil emulsion prepared by high-pressure homogenization. The formulation of the emulsion was developed with regard to oral compatibility and enhancing properties of the excipients. A fine and stable dispersion of the aqueous phase was achieved by a valid complex of emulsifiers dissolved in a mixture of triglycerides. The resulting droplet size distribution was determined by microscopical means and photon correlation spectroscopy (PCS). The stability of insulin in the formulation was examined by ELISA and HPLC methods over a period of 3 months. Human insulin as a high molecular mass peptide (5800 Da) stayed immunologically active after preparation and the formulation showed high compatibility with the peptide in longer term stability by HPLC. The emulsion was able to protect insulin against gastric degradation in vitro without further encapsulation. Simultaneous incorporation of aprotinin as a suitable protease inhibitor was performed.