Liquid penetration into matrices

Abstract

Liquid penetration profiles of hydroxypropylmethylcellulose (HPMC)/drug matrices were studied using propranolol hydrochloride and ibuprofen as model drugs. The kinetics of liquid uptake into these matrices was fitted with different kinetic models. The classical Washburn equation failed to describe fully the liquid penetration into a matrix system compressed with a swelling polymer. A polynomial equation incorporating both Fickian Case I diffusion and Case II relaxational models was found to be more appropriate in these cases. The α-coefficient (Case I component) of HPMC/drug matrices increased with polymer concentration. On the other hand, the β-coeffcient (Case II component) remained relatively unchanged when the polymer content was varied. An increase in the polymer content of HPMC/drug matrices shifts the ratio of the two contributions towards an increase in Case I and a decrease in Case II contributions to overall uptake.