EyeWorld Asia-Pacific March 2016 Issue

March 2016 Glaucoma treatment 22 EWAP SECONDARY FEATURE Extending the duration of glaucoma medications by Maxine Lipner EyeWorld Senior Contributing Writer New formulations and delivery systems W hen it comes to long-term glaucoma therapy, the overarching theme comes down to enhancing adherence, according to Malik Y. Kahook, MD , Slater Family Endowed Chair in Ophthalmology and chief of the glaucoma service, University of Colorado, Aurora, Colo. With approximately 50% of patients not taking their prescribed drops, it’s a matter of figuring out how to heighten usage, he said. To help with this, investigators are examining different approaches of injecting or placing systems in or around the eye that wouldn’t rely on the patient’s compliance. EyeWorld has taken a closer look at this and is highlighting some of the options that are coming down the pike. Richard Lewis, MD , Sacramento Eye Consultants, Sacramento, Calif., pointed out that a variety of approaches are being considered. “Some are nanoparticles that are adherent to the implant or part of the implant,” Only treat floaters in the safe zone (blue), at least 3 mm from both the lens and the retina. Punctal plugs dispensing medication are another long-term option. This one is seen in the eye under blue light. Punctal plug size in comparison to a dime Source (all): Malik Y. Kahook, MD AT A GLANCE • Numerous medication strategies independent of patient compliance are being considered. • With long-term systems, investigators must deal with concerns about how the drug is released. • Approaches vary from non- invasive systems simply placed on the eye to drug depots inside the eye or even injectable nanoparticles. he said. “Others are reservoirs that are enclosed.” The Ozurdex intravitreal implant (Allergan, Dublin, Ireland) is already available for delivering a corticosteroid (dexamethasone) to the posterior segment, he noted, adding that now Allergan is working on an anterior segment implant as well. “The clinical data has shown these to be safe and effective, and it’s just a question of how long the implant will deliver medications and how long we need to replenish it,” Dr. Lewis said. Surmounting challenges Developing a long-term drug delivery product is very challenging, said Gary D. Novack, PhD , PharmaLogic Development, San Rafael, Calif. “I’ve worked on a number of drug delivery systems in ophthalmology over the years, and it’s more complicated than it seems,” Dr. Novack said. “At a minimum doing drug delivery is adding another dimension to dose response.” In addition to the usual concentration and frequency with these systems, investigators must consider just how the drug is being released, he explained. The idea of using such an approach for glaucoma has been around for some time. There was the Ocusert product (Alza, Mountain View, Calif.) for delivering the short-acting drug pilocarpine, Dr. Novack said. It was a great way to deliver the pilocarpine at a consistent, nearly zero-order rate for the life of the product, he said, adding that while it was very good for consistently releasing the drug, it did have a downside. “It created another