“…[4][5][6][7][8] Several beneficial characteristics of hydrogels 9,10 allow their use as drug delivery systems for oral, nasal, buccal, rectal, vaginal, ocular, and parenteral routes of administration. 1,5 Polymers from natural, synthetic, or semisynthetic sources can be used for synthesizing hydrogels for delivery of both hydrophilic and hydrophobic drugs, 4,7,[10][11][12][13][14][15][16] with cylindrical and spherical hydrogels being commonly used. 1,5 Drugs are commonly incorporated into hydrogels by physical entrapment, by either placing a preformed hydrogel in a suitable drug solution or letting the hydrogel monomer(s), mixed with drug, an initiator, and, if necessary, a crosslinker, polymerize.…”