ABSTRACT
Hydrogels.......................................................................................................................................... 83 Introduction .................................................................................................................................. 83 Physical and Chemical Properties of Hydrogels ......................................................................... 84
Applications of Hydrogels and Patches in Transdermal Delivery.................................................. 87 Hydrogels...................................................................................................................................... 89 Transdermal Patches..................................................................................................................... 90
Conclusions ...................................................................................................................................... 91 References......................................................................................................................................... 91
Hydrogels date back to 1960 when Wichterle and Lim first proposed the use of hydrophilic networks of poly(2-hydroxyethylmethacrylate) (PHEMA) in contact lenses [1]. Since then, the use of hydrogels has extended to various biomedical [2] and pharmaceutical [3] applications. In particular, due to their physical properties similar to those of human tissues (water content, soft, and pliable consistence) hydrogels have been used for different administration routes such as oral, rectal, ocular, epidermal, and subcutaneous [3, 4].
