Comparison of oil-in-water emulsions manufactured by microfluidization and homogenization

The purpose of this study was to compare drug-free model submicron oil-in-water (o/w) emulsions manufactured by high-speed homogenization and microfluidization. The study was aimed at evaluating the influence of these two manufacturing processes on the stability of the emulsions with respect to emulsifier concentration. Stability was defined in terms of dispersed droplet diameter growth over time. The study was also directed towards identifying the minimum emulsifier concentrations required by either processing method within the same model o/w systems to produce emulsions viable throughout the study period of three months. The Microfluidizer 110L was found to be more effective than the homogenizer in producing stable o/w submicron emulsions using triglycerides of caprylic/capric acid as the oil phase and combinations of emulsifiers (polyoxyethylene sorbitan oleate with high HLB and sorbitan monooleate with low HLB) at low emulsifier concentrations. Submicron emulsions prepared by the microfluidization process had smaller droplet diameters and exhibited less droplet diameter growth over time compared to high-speed homogenization. At emulsifier concentrations below 20% w/w, the droplet diameter or stability of the dispersed phase of the sub-micron emulsions prepared by either process was found to be dependent on the emulsifier content.