Submicron emulsions as drug carriers - Studies on destabilization potential of various drugs

Few drugs have been successfully formulated as submicron emulsions. The phy sicochemical stability of submicron emulsions on admixture of drugs is the main factor limiting a wider use of this type of vehicle for parenteral or other routes of administration. In a short-term stability studies we have i nvestigated 35 drugs with regard to their compatibility with 20 or 5% paren teral fat emulsions. The study has shown that interaction of drugs with sub micron emulsions is complex in nature. Taking into consideration the physic ochemical properties: of a drug e.g. lipophilicity or ionization, it is dif ficult to predict changes in the physical stability of the system. If desta bilization occurs it is maximal at saturated concentrations and the presenc e of even significant amounts of the solid phase formed by undissolved drug does not influence the short-term stability of the system. Due to the incr eased ratio of emulgator to oil, emulsions containing 5% of oily phase are less susceptible to destabilization than 20% emulsions. (C) 2001 Elsevier S cience B.V. All rights reserved.