Effect of additives on liquid uptake into hydroxypropylmethylcellulose matrices

Abstract

The penetration of water into hydroxypropylmethylcellulose (HPMC)/propranolol matrices containing 25% HPMC K15 and varying quantities of an additive was studied. The kinetics of liquid uptake into these matrices was fitted with a second-order polynomial equation incorporating both Fickian Case I diffusion and Case II relaxational models. Lactose improved the Case I uptake into HPMC/propranolol matrices. However, Case I uptake was reduced in matrices with dicalcium phosphate compared with matrices with lactose. Starch had a minimal effect on the overall water uptake profile. It improved Case I transport marginally but did not affect Case II transport. Sodium carboxymethylcellulose (NaCMC) altered the water penetration profile of HPMC/propranolol matrices two-fold. The presence of 50% NaCMC in the matrices encouraged higher water uptake whilst matrices with 25% NaCMC increased the water uptake only during the initial stages.