T. Yoshioka et al., A NONIONIC SURFACTANT VESICLE-IN-WATER-IN-OIL (V W/O) SYSTEM - POTENTIAL USES IN DRUG AND VACCINE DELIVERY/, Journal of drug targeting., 2(6), 1995, pp. 533-539
An aqueous dispersion of niosomes (non-ionic surfactant vesicles) emul
sified in an external oil phase forms the vesicle-in-water-in-oil (v/w
/o) system described in this paper. The properties of the surfactant u
sed to form the vesicles, the surfactant or surfactant mixture used to
stabilize the emulsion and the nature of the oil phase can be changed
to provide systems of different capacities for drug or antigen and di
fferent release characteristics. The same nonionic surfactant is used
as the principle amphipile to form the niosomes and to stabilize the w
/o emulsion, thus promoting stability by decreasing transfer of surfac
tant between the stabilizing monolayers and the vesicle bilayers. The
in vitro release of carboxyfluoroscein and 5-fluorouracil encapsulated
within the niosomes of the v/w/o system has been investigated, the na
ture of the oil phase and surfactant-oil interactions being important
in determining the rate of solute release. Initial studies of the syst
em in vivo, as an adjuvant for tetanus toroid, using cottonseed oil as
the external oil phase, showed enhanced immunological activity over t
he free antigen or vesicles.