ION-EXCHANGE RESINS FOR OPHTHALMIC DELIVERY

A new novel delivery system for ophthalmic drugs was developed using a n antiglaucoma agent Betaxolol Hydrochloride as a model. The new deliv ery system involved both the binding and release of drug from ion exch ange resin particles. Betaxolol was studied in-vitro via a release mod el analysis. The ocular comfort of Betaxolol was greatly enhanced by r educing the availability of free drug molecules in the precorneal tear film. The amount of resin concentration was selected to obtain optimu m binding of the drug. The zeta potential of suspended particles was a djusted to produce flocculated suspension. Drug resin particles were t hen incorporated into the structured vehicle, containing Carbomer 934P as a polymer, to enhance the physical stability and ease of resuspend ability of the product. This delivery system also optimized the bioava ilability of Betaxolol, reducing the total drug concentration in half to 0.25% Betaxolol in 0.25% BETOPTIC S Ophthalmic Suspension as compar ed with 0.5% Betaxolol in BETOPTIC 0.5% Sterile Ophthalmic Solution do sage form. Increased comfort of 0.25% BETOPTIC S Ophthalmic Suspension , as well as its bioequivalency data in animal models (rabbits), was c onfirmed in actual clinical trials of the product 0.25% BETOPTIC S Oph thalmic Suspension. The 0.25% BETOPTIC S Ophthalmic Suspension product has been approved by FDA and is marketed in U. S. since February 1990 . The 0.25% BETOPTIC S Ophthalmic Suspension formulation has an increa sed bioavailability (equivalent to BETOPTIC 0.5% Sterile Ophthalmic So lution at half the concentration of drug); and pharmaceutically, is an elegant suspension product which settles slowly providing uniform dos age and increased ocular comfort.