Abstract:

This paper concerns with matrix-diffusion mechanism in slab monolithic matrixin the case that a drug loading is above its saturation level. A comprehensive model is proposed andthe general solutions are acquired by Laplace transform, from which a special case can be derived.The equations obtained are compared with Higuchi's model and tested with a 5-fluorouracil(5-Fu) loaded poly (ethylene-vinylalcohol), i. e., 5 -Fu/EVAL matrix system. The experimental data haveconfirmed the validity of the theoretical model at middle drug loadings, e.g., those between 15.5 and 123.6 mg.cm^-3. The model proposed is superior to Higuchi's for a relatively low loading system, muchas that less than 15.5 mg.cm^-3 and can theoretically support the hypotheses of Higuchi's model.Neither of these two theoretical models can describe the high drug loading systems, such as thoseloaded over 210 mg.cm^-3. This case has been discussed elsewhere.

Key words: 5-Fluorouracil(5-Fu), Poly(ethylene-vinyl alcohol), Modeling, Planar matrix, Sustained drug