The effect of oil components and homogenization conditions on the physicochemical properties and stability of parenteral fat emulsions

The stability and physicochemical properties of different parenteral emulsion formulations containing 20% oil phase stabilized with soya lecithin were examined. Oil mixtures of castor oil with either soybean oil or middle-chain triglycerides (MCT) yielded very fine mean particle sizes (130-140 nm), which remained stable over 9 months. Moreover, a further aim was to produce emulsions containing 30% oil phase with small mean particle sizes and moderate viscosity. By optimizing the homogenization process and using only 1.5% soya lecithin, emulsions with 30% oil phase consisting of castor oil and MCT 1:1 with particle sizes in the range of 135-145 nm and moderate viscosity (3.8-3.9 mPas) could be prepared. These emulsions showed good stability over 9 months. The stability of these emulsions could be correlated with the decrease in interfacial tension by using castor oil as a component of the oil phase. This study shows the dominating influence of the nature of the oil phase as well as the importance of the homogenizing conditions on processing and stability. (C) 1998 Elsevier Science B.V. All rights reserved.