Investigation of timolol maleate release from alginate-kappa carrageenan hydrogel systems

Glaucoma disease caused by increased intraocular pressure leads slow and permanent damage of the optic nerve at the back of the eye. The timolol maleate is used as an anti-glaucoma agent and reduces intraocular pressure. In this study, timolol maleate molecules were loaded into biocompatible alginate-kappa carrageenan hydrogel membranes and beads the release of timolol maleate molecules from these hydrogels was investigated in artificial tear fluid at 37°C. Alginate-kappa carrageenan hydrogel membranes and beads, which were synthesized by physical crosslinking with calcium chloride and potassium chloride solution, were characterized by using Fourier Transform Infrared Spectrophotometer (FT-IR), Differential Scanning Calorimetry (DSC) and Scanning Electron Microscopy (SEM). M7 membrane which has alginate/kappa-carrageenan ratio of 1.0/0.04 and was crosslinked by 10% salt solution showed the highest drug loading value of 94.2%. As the kappa-carrageenan concentration of hydrogels increased more smooth shaped membranes and beads were obtained. The cumulative release of timolol maleate from hydrogels decreased with increasing the salt concentration that used in crosslinking. The highest cumulative release was obtained as 73.5% with M5 membrane which has alginate/kappa-carrageenan ratio of 1.0/0.02 and was crosslinked with 4% salt solution. Keywords: Glaucoma, timolol maleate, alginate, kappa-carrageenan.