EFFECT OF ADDITIVES ON LIQUID UPTAKE INTO HYDROXYPROPYLMETHYLCELLULOSE MATRICES

The penetration of water into hydroxypropylmethylcellulose (HPMC)/prop ranolol matrices containing 25% HPMC K15 and varying quantities of an additive was studied. The kinetics of liquid uptake into these matrice s was fitted with a second-order polynomial equation incorporating bot h Fickian Case I diffusion and Case II relaxational models. Lactose im proved the Case I uptake into HPMC/propranolol matrices. However, Case I uptake was reduced in matrices with dicalcium phosphate compared wi th matrices with lactose. Starch had a minimal effect on the overall w ater uptake profile. It improved Case I transport marginally but did n ot affect Case II transport. Sodium carboxymethylcellulose (NaCMC) alt ered the water penetration profile of HPMC/propranolol matrices two-fo ld. 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.