You must have heard about drug eluting stents that help in opening of the clogged coronary arteries in heart. A startup venture, Eyenovations brings hope to patients with eye problems such as glaucoma, who have to use eye drops several times a day, by discovering a drug eluting contact lens. The eye lens is expected to continuously provide release of drugs for extended period of time. Drug eluting contact lens is developed in collaboration with researchers from MIT, Massachusetts Eye and Ear Infirmary, and Children’s Hospital Boston.
What is a drug eluting contact lens?
Contact lens is the medical device that is inserted into the eye to correct vision. The contact lens is mostly formed of silicone hydrogel material. A polymer film is coated inside the hydrogel material of contact lens that contains the medication or drug e.g. ciprofloxacin.
The coating material used to develop the prototype contact lens was PLGA (Poly[lactic-co-glycolic acid]). Scanning electron microscope was used to characterize the coatings that encapsulated fluorescein or ciprofloxacin.
How does the drug eluting contact lens work?
The medicine encapsulated in the polymer film is gradually released from the contact lens. This gradual release of the medication is supposed to fulfill the requirements of the dose required by a patient.
Researchers studied the release characteristics by continuously shaking the coated lens in phosphate buffered saline solution at 37 degree Celsius (room temperature). Also Ciprofloxacin released from the contact lens was studied in an antimicrobial assay to verify antimicrobial effectiveness.
The release profile was characterized by a brief and minimal initial burst in the prototype contact lens. Thereafter, the lens demonstrated controlled release of the drug for over 4 weeks.
Can I get contact lens as per my dosing requirement?
It is possible to design the drug containing coating to have desired release characteristics. Basically, the rate of drug release can be controlled by altering properties of the polymer film (like molecular weight) and drug ratio (amount of drug in polymer)
150%; font-family: 'Arial','sans-serif';">In the prototype lens, either the ratio of drug to PLGA or the molecular weight of the PLGA was changed to alter the rate of drug release. It was found that both the PLGA and the pHEMA affected release kinetics.
What is the expected time duration of release of drug?
Eyenovations are planning to commercialize lenses that can deliver drugs for up to 30 days – the FDA’s limit for single-use contact lenses. Also, the Eyenovations team has found a way to make their lens deliver high doses of medication for up to 100 days. They are in the process of patenting this discovery.
What are more developments in the area of drug eluting contact lens?
Daniel Kohane, director of the Laboratory for Biomaterials and Drug Delivery at Children’s Hospital in Boston, stated that in future models it may be possible to infuse the medication directly into the hydrogel material of the lens. From cost and manufacturing point of view, this may reduce the cost and complexity of coating the drug-polymer layer on the lens.
Similar work is under progress by a lens manufacturer CIBA Vision. Lynn Winterton, global head of research stated that R&D efforts are directed toward incorporating lubricants that elute over time. In fact, in early 2008 FDA approved a daily disposable lens having a lubricant that is forced out with each blink of the eye.
Dr. Nichols, assistant professor of optometry and vision science at The Ohio State University College of Optometry, says that drugs that might be incorporated into contact lenses may include anti-allergy, antimicrobial or anti-dry eye medications.
Original published article “A drug eluting contact lens” can be accessed through Investigative Ophthalmology and Visual Science.