Hydroxypropyl Cellulose (HPC) Membrane

Hydroxypropyl cellulose (HPC) is a water-soluble polymer, often used as a thickening agent, a tablet binder, and a film-coating material for drug release. Combining with ethyl cellulose (EC) or cross-linked with polyacrylic acid, HPC can be used as a mucoadhesive delivery system or oral delivery system, where the drug release rate and the drug dosage can be controlled (Kamel et al. 2008). Figure 1shows the synthetic route for making hydroxypropyl cellulose. The hydroxyl groups on the glucose unit of cellulose can be partially or completely substituted by hydroxypropyl groups through an etherification reaction. The maximum molar substitution is 3, and consequently, the viscosity of the polymer increases with the degree of polymerization. The broad range of accessible viscosity leads to different applications in pharmaceutical formulation, e.g., hydroxypropyl cellulose with low viscosity has been used as tablet binder, while those with medium and high viscosities have been used in the...