Studies on the release of solubilized drugs from ointment bases. Part 9: Modelling of drug release process of active substance from emulsive ointments (W/O)--the mathematical model.

A new mathematical model of the release process of solubilized active substance from emulsive (W/O) ointments is proposed. This model is based on Fick's diffusion law and additional assumptions. The most important assumption is recognition of the heterogeneous character of emulsive ointments. An equation has been derived, which expresses the functional relationship between the quantity of substance liberated from the ointment and the period of release.