A novel ion-activated in situ gelling ophthalmic delivery system based on κ-carrageenan for acyclovir.

The aim of this study was to prepare and evaluate ion-activated in situ gel ophthalmic drug delivery system based on κ-carrageenan (KC), using acyclovir as a model drug, hydroxypropyl methylcellulose (HPMC) as the viscosity agent and hydroxypropyl-β-cyclodextrin (HP-β-CD) as the penetration enhancer. The two ternary phase diagrams exhibited the effect of K and Ca on the sol-to-gel transition, which turned out that KC was more sensitive to K. The optimal ophthalmic matrix (prepared from KC and HPMC) was optimized with in vitro drug release test. The apparent permeability coefficient of acyclovir under 2% HP-β-CD was found to have dramatically increased (2.16-ploid) than that of conventional eye drops (p < .05). The ion-activated in situ gel based on KC significantly delayed drug release and its bioavailability could be improved in comparison with the conventional eye drops. Hence, it has the potential to be a novel kind of ocular drug delivery system.