The rate of mass transfer per area unit is, among other factors, related to the shape of polymeric chains within the dosage form. Higher tortuosity or curviness retards mass transfer as it acts obstructively on the drug particles within the formulation.
The speed at which a substance moves through a dosage form is influenced by several factors, including the shape of polymer chains.  More twisted or curved chains slow down the movement of drugs because they create obstacles for the particles.