A new long acting ophthalmic formulation of Carteolol containing alginic acid

Alginic acid was evaluated as a potential vehicle in ophthalmic solutions f or prolonging the therapeutic effect of carteolol. This anionic vehicle was expected to slow down drug elimination by the lacrimal flow. both by under going in-situ gel formation and by interacting with the mucus. In vitro stu dies indicated that carteolol is released slowly from alginic acid formulat ions. suggesting an ionic interaction. The adhesive behavior of alginic aci d solution was better than that of another polymer, hydroxyethylcellulose ( HEC). Intraocular pressure (IOP) measurements of rabbit eyes treated with a 1% carteolol formulation with or without alginic acid showed that this pol ymer significantly extended the duration of the pressure-reducing effect of carteolol to 8 h. The increased ocular bioavailability of 1% carteolol in the presence of alginic acid led to an equivalent concentration in the targ et tissue although administration was only once a day compared with twice a day for 1% carteolol alone. The overall results of this study indicate tha t the alginic-acid vehicle is an excellent drug carrier, well tolerated, an d could be used for the development of a long-acting ophthalmic formulation of carteolol. (C) 2000 Elsevier Science B.V. All rights reserved.