Tabriz University of Medical Sciences Advanced Pharmaceutical Bulletin 2228-5881 7 4 2017 12 31 Cross-Linked Hydrogel for Pharmaceutical Applications: A Review 515 530 10.15171/apb.2017.064 EN Rabinarayan parhi REVIEW 10.15171/apb.2017.064 2017 04 13 2017 09 16 Hydrogels are promising biomaterials because of their important qualities such as biocompatibility, biodegradability, hydrophilicity and non-toxicity. These qualities make hydrogels suitable for application in medical and pharmaceutical field. Recently, a tremendous growth of hydrogel application is seen, especially as gel and patch form, in transdermal drug delivery. This review mainly focuses on the types of hydrogels based on cross-linking and; secondly to describe the possible synthesis methods to design hydrogels for different pharmaceutical applications. The synthesis and chemistry of these hydrogels are discussed using specific pharmaceutical examples. The structure and water content in a typical hydrogel have also been discussed.