Fig. 6.

Metamorphosis of the calcipotriene and betamethasone dipropionate foam. From the solution in the manufactured product, in which the drugs are dissolved, and upon application and collapse of the foam, the drug’s attain their saturation solubilities (and maximum diving forces for skin penetration), and then create a residual ‘ointment’ film where a transient period of supersaturation may occur and in which thereafter finite amounts of the drugs remain in solution (at saturation) to sustain delivery