APPLICATION OF TRIANGULAR PHASE DIAGRAMS TO INVESTIGATE THE FORMULATION CONDITIONS OF PHARMACEUTICAL MICROEMULSIONS

AIM　To establish innovational triangular phase diagrams for preparation of pharmaceutical microemulsion (ME) with low toxicity as a result of reducing the amount of the emulsifiers. METHODS Lecithin and polyoxyethylene octyl phenyl ether (OP) were used as emulsifiers (E), absolute alcohol and n-octyl alcohol as assistant emulsifiers (A), ethyl oleate and olive oil as the oil phase (O). For the innovational triangular phase diagrams, lecithin-ethyl oleate-water and absolute alcohol (optimized ratio W/A=0.6)system, and OP(olive oil and n-octyl alcohol (O/A=0.34)-water system were used for preparation of the ME. While for the traditional triangular phase diagrams, OP and n-octyl alcohol (E/A=K_m=1.5)-olive oil-water system, lecithin and absolute alcohol (E/A=K_m=1.12)-ethyl oleate-water system were used. Then, the corresponding amounts of the emulsifiers used in both methods were compared. RESULTS　In the ME of lecithin systems by the innovational and the traditional methods, the amounts of emulsifier are 6%-28% and 28%-29.6%, respectively. In the ME of OP systems by the innovational and the traditional methods, the amounts of emulsifier are 23%-40% and 27.6%-49.8%, respectively. CONCLUSION　The method of innovational triangular phase diagram for preparation of ME is superior to the traditional method in finding out the lower amounts of emulsifiers for ME, and is a feasible method with guiding significance for preparing ME.