Failure of calcium gluconate internal gelation for prolonging drug release from alginate–chitosanbased ocular insert of atenolol

Abstract

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.