Abstract:

The effect of additives on the rate of release of a drug (or a marker) from the internal phase of a multiple emulsion (water/oil/water) (w/o/w) without causing a decrease in its stability was studied. Electrolytes were added to the internal and/or external aq. phase in order to equalize osmotic pressures of the two aq. phases. Addn. of electrolytes to the outer phase does not slow the rate of drug migration while incorporation of electrolytes and drug to the inner phase decreases the leaching rate. The electrolytes, both cations and anions, which improve the salting-in effect of the emulsifier are effective in decreasing the drug transport. The drug transport can be controlled by altering the electrolyte-surfactant interaction at both interfaces. The right balance between counter-current flow of electrolytes and water in each direction is crit. for such control. [on SciFinder(R)]