Now, drug-delivering contact lenses

WASHINGTON - Glaucoma patients and dry-eye sufferers may soon be able to trade their messy eye drops for a contact lens that delivers medication gradually over time, say scientists.

Medication through eye drops tends to be highly ineffective, not because the drugs are impotent, but because of the body's own natural defences.

Blinking and watery eyes are normally beneficial ways to stop foreign objects from coming into contact with the delicate membrane of the eye.

However, when it comes to medication, such reactions are less than favourable and cause as little as 1 to 7 percent of the dose is actually absorbed by the eye.

To combat this problem, a research team, led by Daniel Kohane, MD, PhD, director of the Laboratory for Biomaterials and Drug Delivery at Children's Hospital Boston, has created special contact lenses that can gradually dispense a constant amount of medication to the eye, at adjustable rates.

Kohane and colleagues at the Department of Chemical Engineering at the Massachusetts Institute of Technology (MIT) created a two-layer contact lens with an inner drug-bearing biodegradable polymer film known as PLGA.

Both PLGA and pHEMA (used for the coating) have been well studied and are already approved for ocular use by the Food and Drug Administration.

In laboratory testing, the prototype lenses dispensed ciprofloxacin (an antibiotic often used in eyedrops) for 30 days, the longest duration for which contact lenses are currently approved by the FDA; in some tests, the lenses continued releasing drug for up to 100 days.

The amounts dispensed were sufficient to kill pathogens in a laboratory assay.

The researchers have started testing the lens in animals and plan to begin human testing as soon as possible.

The lens has been described in the July issue of Investigative Ophthalmology and Visual Science. (ANI)


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