Theoretically, it could incorporate into the membrane during co-permeation, increasing its rigidity and decrease its permeability for CF. Further correlative evidence for this hypothesis is the plot of the relative amount released. When CF is mixed with this substance, the curve has no inflexion point, as is the case for all mixtures with other substances. At the same time, however, its incorporation does not seem to affect the partition coefficient in any way, so its presence does not displace CF from the membrane.