Comparative study of two preparation methods of w/o/w emulsions: Stirring and membrane emulsification

Since a membrane method which employs a porous glass membrane for preparation of water-in-oil-in-water (w/o/w) emulsion from water-in-oil emulsions has been developed recently, a comparative study was made of properties of w/o/w emulsions prepared by a two-stage stirring method and this membrane method, w/o/w emulsions encapsulating cytarabine, doxorubicin and vancomycin, were prepared by the two techniques using the same formulation, Particles of the w/o/w emulsion prepared by the stirring method were less homogeneous, whereas particle distribution of the emulsion prepared by the membrane method was sharp and close to monodispersion, The mean particle size depended on pore size of the membrane, The membrane method proved the more useful of the two for encapsulation of low molecular weight drugs, Drug release from the emulsion prepared by this means was slower than that from the emulsion prepared by the stirring method, The membrane method was therefore found useful for preparation of a homogeneous w/o/w emulsion, effective encapsulation of small drugs and control of drug release.