Slow release hydrophilic matrix systems; investigation of the interactions between water and hydroxypropylmethylcellulose

摘要

Hydroxypropylmethylcellulose (HPMC) is a non-ionic cellulose ether which has been widely studied for its applications in slow release hydrophilic matrix systems. When HPMC matrices are exposed to an aqueous medium, the polymer interacts with water, swells and hydrates to form a gel-like barrier around the core of the tablet. This barrier controls the core of the tablet. This barrier controls the ingress of water into, and also release of drug from the device. The structure across this barrier is complex and it is not homogenous (2). It has been shown that the water mobility across the gel barrier is not uniform (3). In has been shown that the water mobility across the gel barrier is not uniform (3). In addition, depending on the levels of methoxyl and hydroxypropoxy. substitution, the water mobility and therefore drug release from these matrices vary (3). Therefore, the interaction between water and HPMC polymers play a critical role in the initial gel formation and also subseuqent drug release from their matrix tablets. Here, some fundamental studies have been carried out to characterise the nature of this interaction and also investigate the factors that may influence the interaction between water and HPMC polymers.