The influence of selected properties on the stability of pharmaceutical emulsions

Assessment of stability for paraffin and soybean systems of emulsions have been carried out with the use of selected emulsifiers. The influence of microelements upon the stability of the investigated emulsions has also been considered. The soybean and paraffin emulsions stability research has been carried out with the use of oscillatory and centrifugal tests. On analysis of the results it has been found that it is necessary to select a proper emulsifier for the oil used. The paraffin emulsions--excluding those containing methyl cellulose (MC), hydroxyethyl cellulose (HEC), Span 20 and lecithin--broke after 4 month of storage. There was an immediate demulsification observed in case of soybean emulsions matched with these emulsifiers: MC, HEC, Span 20, 40, 65, 81 and lecithin. An average globule size has approximately doubled. Adding microelements to the examined emulsions caused a loss of stability. The oscillatory test is useful for a quick assessment of emulsive system stability.