Failure of calcium gluconate internal gelation for prolonging drug release from alginate-chitosan-based ocular insert of atenolol

Background: The aim of the investigation was to develop and evaluate ocular polymeric film of atenolol for the management of glaucoma. Materials and Methods: Fixed concentration blends of sodium alginate (NaAlg) and chitosan were combined with the varying concentration of calcium gluconate and the resulting hydrogels were casted as ocular films. Various physicochemical studies and in vitro release tests of the prepared films were carried out to study the effect of calcium gluconate addition to alginate-chitosan blend films. Results: Cumulative % drug released from the formulations ranged from 95 to 99% within 5- to 12-hour period. The drug release enhanced with incorporation of higher ratios of calcium gluconate. F1 (2% NaAlg and 1% chitosan without calcium gluconate) sustained the drug release for the longest period of time (12 hours). Addition of calcium gluconate to the formulation resulted in faster drug release rather than sustained drug release. Conclusion: The results showed that the addition of calcium gluconate leads to a change in the release capacities of the matrices. Despite the presence of calcium ions and thus the possibility of an ionic interaction, the internal gelation of the polymer matrix lead to enhanced drug release and poor sustaining of drug. The sustained release effect of NaAlg-chitosan matrices alone was the best among the formulations studied.