抄録
A study was carried out with a liquid droplet dispersion system ointment (LDDS) using mometasone furoate as the drug and ethyleneglycol salicylate as the solvent. First, drug concentrations in the bleeding liquid (CBL) and in the liquid droplet (Cs) were determined. It was suggested that a partition equilibrium is established between the two.Next, an in vitro drug release test was performed. A slope obtained from plotting the cumulative amount of the drug released against the square root of time was used as an index of release. With changes in the drug concentration in ointment (Co) at a definite solvent concentration in ointment (So), Co was proportional to the slope. The result predicted from CBL based on the theory of thermodynamic activity corresponded with that of the actual in vitro drug release. On the other hand, with changes in So at definite Co, the slope remained nearly constant, regardless of changes in So. The result predicted from C<BL> based on the theory of thermodynamic activity did not correspond with that of the actual in vitro drug release.Thus, further studies from various theoretical aspects were done. It was confirmed that a proposed equation for LDDS can be put in order similar to ones either for a soluble type or a crystal dispersion type. In this process, the volume fraction of the liquid droplet phase was suggested to be an important parameter for LDDS. Further, good correlation between the found values and the proposed equation was noted. Therefore, the validity of the proposed equation was verified.
