Question

The dissolution of aspirin tablet is controlled by the diffusion of the drug into the surrounding stomach fluid. The table has a radius R. The drug concentration at the surface is always saturated, ie, C(r=R)=C0. What is the drug concentration profile outside the tablet in the stomach fluid? State all your assumptions and boundary conditions in your calculation.

Answer 1

Eleven different compounds representing various classes of buffering agents were studied with respect to their effect on the dissolution of aspirin from tablet formulations. In general, carbon dioxide-producing buffering agents (sodium bicarbonate, magnesium carbonate, and calcium carbonate) gave more rapid dissolution than the readily water-soluble buffering agents (sodium ascorbate and sodium citrate), and both of the preceding classes of buffering agents gave much faster dissolution than water-insoluble buffering agents such as magnesium and aluminum compounds.