Diffusional release of a dispersed solute from a cylindrical polymeric matrix into an infinite external volume

Numerical and analytical exact solutions of diffusional release from a cylindrical polymeric matrix into an infinite medium have been developed in which the initial solute loading (A) is greater than solubility limit (Cs  ). Also, the effects of boundary layers on the drug release rate have been studied. The numerical solution is valid for any initial drug loading whereas analytical solution can be used for high values of drug loading. Comparisons have been made between numerical and analytical exact solutions in upper and lower bounds (A/Cs≫1A/Cs≫1 and A/Cs→1A/Cs→1) and previously presented approximate solution. The presented results validate the proposed numerical solution.