The Soflens^® Contact Lens - An Efficient, Corneal Loading, Drug Delivery System for Antiglaucoma Drugs

Abstract

The results of administering three antiglaucoma drugs to rabbits using drug-loaded Soflens^® contact lenses as drug delivery systems demonstrated a marked enhancement in the miotic activity of the drugs relative to their administration as eyedrops. The use of the Soflens^® systems virtually eliminated side effects of the drugs attributable to their systemic absorption. The lens system effects an efficient transfer of drug to the cornea within 15 minutes after which time it can be removed from the eye without loss of pharmacological activity.

The administration of aqueous solutions of ophthalmic drugs as eye drops is still the conventional method of dosing. Drug solutions, however, are rapidly washed out of the eye by tears; therefore, relatively concentrated solutions are required to produce an adequate level of therapeutic effect. The higher the concentration, however, the more likely it is that a sufficient amount of drug will be lost through lacrimal-nasal drainage passages and subsequent absorption to produce undesireable systemic side effects (1); also, frequent dosing is required with eye drops to maintain therapy. A variety of substances have been added to opthalmic drug solutions to mitigate these problems and to increase the efficiency of this mode of administration (2).