Dissolution at porous interfaces III. Pore effects in relation to the hydrodynamics at a rotating disc surface

Abstract

The dissolution rate-increasing effect of pores drilled into a dissolving tablet surface was studied in a rotating disc apparatus. The increase of the dissolution rate due to one pore, ΔR, was measured as a function of the pore diameter, the pore position and the rotation speed of the tablet surface. From the obtained results the critical pore diameters were determined. They appeared to be inversely proportional to the friction velocity at the surface, a hydrodynamic variable dependent both on the radial position on the surface and on the rotation speed. In addition, ΔR was found to be related to the friction velocity on the one hand and to the extent the pore size exceeds the critical pore diameter on the other.