Self-emulsifying drug delivery systems: assessment of the efficiency of emulsification

Self-emulsifying formulations have potential uses as vehicles for the administration of lipophilic drugs by the oral route. In this study model oil-surfactant mixtures were allowed to self-emulsify under conditions of gentle agitation. During emulsification the relative intensity of light scattered by the dispersion was monitored continuously which enabled the rates of emulsification to be compared. The particle sizes of resultant emulsions were compared by light microscopy and using a Coulter Nano-Sizer. Efficient self-emulsifying formulations were produced by the oils Miglyol 812 or Miglyol 840 in combination with the surfactant Tween 85. The properties of these systems have been studied over a range of mixture compositions. The finest dispersions were produced rapidly and in reproducible time by a mixture of 30% w/w Tween 85 and 70% w/w Miglyol 812.