PROLONGED DRUG RELEASE FROM A CYLINDRICAL MATRIX DEVICE WITH A SMALL RELEASE HOLE

Prolonged drug release from a simple cylindrical device with a small release hole was investigated by a dynamic mathematical simulation model based on the two-dimensional Fick's law of diffusion. Effects of the release hole radius, height and radius of the device, and hydrodynamic diffusion boundary layer formed on the device surface were numerically analyzed. The calculated results indicated that the release rate from the present device can be easily controlled within an effective level of release for a prolonged period of time by an optimum selection of the release hole radius, device radius and device length. The release profiles of numerical calculation were well agreed with the experimental release data of benzoic acid impregnated in the 1% agar gel at the saturated concentration.