The development of polycarbophil as a bioadhesive material in pharmacy

Polycarbophil (PCP), a kind of pharmaceutical polymers with superior bioadhesive properties has been widely used in the field of controlled drug delivery systems. It could be used as a highly efficient thickener, bioadhesive agent, suspending aid and emulsion stabilizer when dispersed in water or other polar solvents. These exceptional utilities of the polymers result from their hydrophilic nature. Hydrogen bonding plays an important role in most adhesion behaviours and becomes the main adhesion force. This paper reviews the applications of PCP in pharmacy over the past decades, and clarifies its unique advantages in the bioadhesive formulations. After an introduction discussing its structural characteristics and action mechanism, the focus turned to the description of its available applications in detail with particular emphasis on the ocular, nasal, vagina and oral drug delivery systems. The other less developed formulations are also described, including the buccal and the transdermal delivery systems.