抄録
In order to investigate the rapidity of transfer of drug molecules from micellar to aqueous phase in nonionic surfactant solutions, theoretical equations were derived assuming that the transfer occurs instantaneously corresponding to the decrease of drug concentration in the aqueous phase. Applicability to the equations was examined with static dialysis of methylparaben, propylparaben and benzocaine in Tween 80 solutions using two kinds of dialysis apparatus at 30°. It was proved that these results were well applicable to the equations and the transfer is instantaneous. But a little increase of dialysis beyond the theoretical value was observed when drug molecules were partitioned predominantly into the micellar phase and the ratio, γ, became large. This phenomenon was attributed to direct dialysis from the micellar phase. Therefore the direct dialysis could be neglected when the ratio, γ, was relatively small. When volume of the outer fluid was enough large, decrease of drug concentration in the inner surfactant solution also became theoretically the first order process and its apparent decreas■g coefficient, Pd, became P′/γ. These relationships were well applied to the dialysis of various drugs.
