People with glaucoma and dry-eye often use eye drops several times a day to treat their condition, but scientists in Boston hope that someday those patients will be able to get their medication simply by wearing special contact lenses.
The researchers, led by Daniel Kohane, MD, PhD, director of the Laboratory for Biomaterials and Drug Delivery at Children's Hospital Boston, have developed contact lenses designed to gradually dispense a constant amount of medication to the eye, at adjustable rates. The researchers describe their prototype lens in the July issue of Investigative Ophthalmology and Visual Science.
Eye drops are currently the most commonly used method of ocular drug delivery, accounting for about 90% of ophthalmic medications, but according to the study authors they are "very inefficient." They note that using eye drops multiple times a day can be difficult for patients to do, and because of blinking and tearing, as little as 1% to 7% of the dose is actually absorbed by the eye.
Kohane told Medical Device Daily that in theory, these drug-releasing contact lenses would be something the patient would only have to change once or twice a month. Simplicity is key because compliance is the main clinical problem the researchers are trying to address, he said.
"Compliance is a real huge problem, particularly in elderly, particularly in those who have very complicated medical regimens," Kohane said. For example, a patient with advanced glaucoma has to use four different prescription eye drops twice a day, often spaced ten minutes apart, he said. "That's a huge time investment, a pain in the backside, and for that reason compliance is really, really poor."
According to the study, other groups have developed drug-releasing contact lenses, but none have been able to achieve a constant, steady release of substantial amounts of drug. Typically, with other types of drug-releasing contacts, a burst of drug is delivered in the first few hours, followed by rapidly dwindling amounts that are too low to be therapeutic, the researchers say.
Kohane, collaborator Joseph Ciolino, MD, of the Massachusetts Eye and Ear Infirmary, and colleagues at the Department of Chemical Engineering at the Massachusetts Institute of Technology (Boston) created a two-layer contact lens with an inner drug-bearing biodegradable polymer film known as PLGA. According to the researchers, both PLGA and pHEMA (used for the coating) have been well studied and are already FDA-approved for ocular use.
In laboratory testing, the prototype lenses dispensed ciprofloxacin (an antibiotic often used in eye drops) 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 not tested the lens in humans yet, but when asked if the patient would be able to feel the medication being delivered Kohane told MDD there is no reason to believe the patient would be able to feel the drugs being delivered. "It would be something they would not notice, or it would be an unusable item," he said.
The scientists plan to begin testing the lens in animals soon and hope to begin human testing as soon as possible, hopefully in a year or so.
Kohane said the materials used to create the lenses are already approved for use in humans and the drugs that would be delivered by the lenses are already being used to treat patients so the researchers don't anticipate any unknown side effects – just those that are already known to occur with the particular drugs being delivered.
The technology recently won the Life Sciences track in MIT's 100K Entrepreneurship competition.
The study was supported by the National Institute of General Medical Sciences at the National Institutes of Health, a Fight for Sight Grant-in-Aid, a Center for Integration of Medicine and Innovative Technology/Johnson & Johnson Young Investigator Award and the Boston KPro Fund, Massachusetts Eye and Ear Infirmary.