Drug-delivering contact lens in development

New lens for sustained-release drug delivery shows promise

A common complaint from physicians when treating patients with chronic diseases is the potential lack of patient compliance, whether intentional (i.e., not refilling prescriptions in a timely manner) or unintentional (i.e., missing the ocular surface when instilling drops). This has become particularly noticeable in elderly patients with diseases such as glaucoma—the literature estimates noncompliance in patients with glaucoma to range from 24%-59%, depending upon the study. Delivering ophthalmic medications through a contact lens is not a new concept—some of the earliest work on the topic dates back to the 1960s; almost three-quarters of ophthalmologists currently use bandage contact lenses in conjunction with topical antibiotic drops, and an overwhelming majority have indicated they would opt to use a drug-eluting contact lens if one was available. To that end, researchers in Boston have developed a prototype contact lens that consists of a thin inner layer of drug-bearing polymer film (PLGA) coated with pHEMA; both are biodegradable and have been approved for ophthalmic use by the Food and Drug Administration. Daniel S. Kohane, M.D., Ph.D., director, Laboratory for Biomaterials and Drug Delivery, Children’s Hospital Boston, Boston, and others have developed a contact lens they say can achieve a constant, steady release of medication. In vitro studies indicate the lens would be able to deliver drugs for up to 100 days,1 but the researchers will limit initial animal and human studies to 30 days, as that is the longest time frame contact lenses have U.S. approval.
Lens specifics

The prototype lens is similar in diameter and thickness to currently available commercial contact lenses, and Dr. Kohane has started a company (Eyenovations, Cambridge, Mass.) to further develop the lens. Dr. Kohane, with Joseph Ciolino, M.D., Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, added the rate of drug release in the lens can be controlled by altering the properties of the polymer film. In laboratory testing with this prototype lens, it was able to dispense ciprofloxacin for 30 days (and up to 100), with the amounts dispensed sufficient to kill pathogens in a lab assay, the university said. There was “no change in the bactericidal activity of the ciprofloxacin in the release medium” at any time point, the researchers noted. The in vitro studies implied “this lens design could continuously deliver a therapeutic concentration of ciprofloxacin to the eye.”1 Current plans include testing other fluoroquinolone antibiotics, and Dr. Kohane said other classes of drugs—including those for the treatment of glaucoma or dry eye—could also be incorporated into the lens design. The researchers acknowledged a potential and relevant concern involves shelf life of the lens, as the PLGA component of the lens could degrade over time, and it is not unusual for contact lenses to be stored at room temperature for months at a time.
Dr. Kohane believes the lens may also have potential for patients in remote or resource-poor areas as a more efficient way to deliver ocular medications.

Editors’ note: Dr. Kohane started Eyenovations (Cambridge, Mass.) to develop the contact lens.

Contact information

Kohane: Daniel.kohane@childrens.harvard.edu

References

1 Ciolino JB, Hoare TR, Iwata NG, et al. A drug-eluting contact lens. Invest Ophthalmol Vis Sci. 2009;50:3346-52.