A collaboration of researchers from MIT, Massachusetts Eye and Ear Infirmary, and Children’s Hospital Boston is opening a promise of contact lenses designed to deliver continuous, extended release of pharmaceuticals. Glaucoma patients might get a particular benefit, as currently many medicines require eye drops to be administered multiple times a day. But as clinicians know, ocular absorption could be used for systemic meds as well.
The team developed a hydrogel lens with a polymer film inside that contains the medication. The medication is released from the contact gradually, and the rate of release can be controlled by altering the properties of the polymer film and the lens. In future models, Kohane [Daniel Kohane, director of the Laboratory for Biomaterials and Drug Delivery at Children’s Hospital in Boston] adds, it may be possible to infuse the medication directly into the hydogel material of the lens.
Several other research groups have explored contact lenses that carry medications, but they have struggled to achieve extended release of the drugs. The Eyenovations team found a way to make their lens deliver high doses of medication for up to 100 days–a process they are now patenting. They plan to develop commercial lenses, using materials approved by the Food and Drug Administration (FDA), that deliver drugs for up to 30 days–the FDA’s limit for single-use contact lenses.
More about the lens from the study abstract:
Methods: Prototype contact lenses were created by coating PLGA (Poly[lactic-co-glycolic acid]) films containing test compounds with pHEMA (poly[hydroxyethyl methacrylate]) by ultraviolet light polymerization. The films, containing encapsulated fluorescein or ciprofloxacin, were characterized by scanning electron microscopy. Release studies were conducted in phosphate buffered saline at 37 degree Celsius with continuous shaking. Ciprofloxacin eluted from the contact lens was studied in an antimicrobial assay to verify antimicrobial effectiveness.
Results: After a brief and minimal initial burst, the prototype contact lenses demonstrated controlled release of the molecules studied, with zero-order release kinetics under infinite sink conditions for over 4 weeks. The rate of drug release was controlled by changing either the ratio of drug to PLGA or the molecular weight of the PLGA employed. Both the PLGA and the pHEMA affected release kinetics. Ciprofloxacin released from the contact lenses inhibited ciprofloxacin-sensitive Staphylococcus aureus at all time-points tested.
No website for Cambridge Eyenovations is available yet…
More from MIT Technology Review…
Abstract in Investigative Ophthalmology and Visual Science: A drug-eluting contact lens
Image: Scanning electron microscope image of antibacterial agent ciprofloxacin suspended in a biodegradable polymer.
