Factor That Affect the Emulsion

Factor : Size of droplets Other than emulsion stability and viscosity , the droplet size of the oil also do influence in the formulation of the Parenteral nutrition emulsions. This can be seen in the creaming of an emulsion. The creaming of an emulsion is best explained by the Stokes’ equation: Where ( ) is the rate of creaming , r is average radius of the droplet, (po-pw) is the different density between oil phase and water phase, g is the gravity and n is refer to the viscosity of the emulsion. [ David Jones, Pharmaeutics- Dosage Form and Design. First edition. Pharmaceutical Press 2008, page 54]
Based on the Stokes’ equation , the rate of creaming will be directly propotional to the average radius of the oil droplet (droplet size). When the value of the average radius, r increase, the rate of creaming( ) will also increase. The rate of creaming can be reduce by reducing the average particle size of the disperse phase like the size reduction methods namely colloid mill[ David Jones, Pharmaeutics- Dosage Form and Design. First edition. Pharmaceutical Press 2008, page 54] . Besides, there is a problem that associated with the size of droplet with the use of parenteral emulsion that potentially restricted their pharmaceutical use. When administered intravenously, we must make sure that the droplet size is less than 1μm in order to prevent the blockage of the blood flow within capillaries. If the droplet size is more than 1μm , it is potential that the emulsion will block the flowing blood in the capillaries. In addition, the physical instability of the emulsion that cause the droplets of the internal phase to coalesce is also potential dangerous outcome of poorly formulated emulsion. [ David Jones, Pharmaeutics- Dosage Form and Design. First edition. Pharmaceutical Press 2008, page 125 and