Title: Emulsions and Emulsifications Methods and Processes | LLS Health CDMO
Headings: Emulsions and Emulsifications
Emulsions and Emulsifications
Table Of Contents hide
Emulsification
Stabilization
Addition of API
Conclusions

Content: This energy usually comes from mechanical shear provided by various types of mixers, and the final droplet size of the emulsion is dependent on not only the chemistry but also the amount of energy applied. Simple paddle-type mixers are suitable when the required droplet size is above ~10 µm but to make smaller droplets, higher shear is generally required. High shear rotor-stator mixers are commonly used. These operate by pumping the emulsion phases through the narrow gap between a perforated cylinder (the stator) and the blades of a rapidly rotating stirrer housed inside it (the rotor) where the forces are sufficient to make droplets as small as around 1 µm (Figure 2). To make even smaller nano-sized droplets, at small scale, ultrasonic devices can be used, but they are generally not practical to scale up. High-pressure homogenizers are readily scaled and can also produce emulsions with nano-sized droplets. The emulsion phases are pumped together under high pressure into a small volume or through a small orifice – the interaction chamber where pressures in the tens of thousands of PSI create very high shear forces (Figure 3). Emulsions with an average droplet size as small as 0.2 µm can be formed this way, which is significant as these are amenable to sterilization by filtration through a 0.2 µm filter. Emulsions are prepared by adding one phase to the other over time, with one or both phases containing emulsifier, and applying shear. In some cases, one or both phases are heated prior to mixing to aid emulsification.