Eyeworld

54 | EYEWORLD | NOVEMBER 2019 G UCOMA PHARMACEUTICAL FOCUS by Maxine Lipner EyeWorld Senior Contributing Writer There is also a travoprost-loaded punctal plug (Ocular Therapeutix). This system also resides in the punctum and canaliculus. It is a polymer-carrying system that delivers drug slowly to the tear film in a similar fashion to the Mati plug, Dr. Kahook explained, adding that in this case, however, the plug does not have a faceplate and swells in place after insertion. Unfortunately, the plug may migrate into the distal outflow system with- out anyone recognizing this, thereby affecting efficacy, Dr. Kahook continued. A third option, the bimatoprost ring (Al- lergan), elutes the drug directly into the tear film, Dr. Kahook said. It is placed noninvasively over the eye in a manner similar to a large-di- ameter contact lens, and can carry a larger drug load than the plugs, he continued. Meanwhile, the cons include potential discomfort due to rubbing on the ocular tissue, as well as cosmetic issues since the device is visible along the medi- al canthus, Dr. Kahook said. Yet another modality is the topical drug de- livery device (TODDD, Amphorex Therapeu- tic), which Dr. Bacharach describes as similar to the ring. "This is a soft elastomeric struc- ture that floats atop the sclera underneath the eyelid," he said. "It elutes drug from different reservoirs and you can do multiple drugs." An early attempt at iGAP was the subcon- junctival use of anecortave acetate (Graybug Vision). This involves microparticles that can deliver the drug over several weeks to several months via a subconjunctival injection, Dr. Bacharach noted. What to expect Efficacy with all of these surface systems can be somewhat limited. "To date, external devic- es, such as plugs and rings, have not achieved prostaglandin-like efficacy, with most achieving T hese days a variety of sur- face-based systems for delivering glaucoma medication to the eye are being ex- plored to overcome patient adherence problems, peak and trough delivery, and other issues. Among these are devices such as punctal plugs, contact lenses, ring delivery systems, micro-particle platforms, and more. EyeWorld asked two specialists to consider what these options have to offer. Such systems fall under the umbrella of platforms that are external to the eye, dubbed eGAPs (external-guided administration of pharmaceuticals), according to Jason Bacharach, MD. Meanwhile, the other type of sustained delivery system—iGAPs (internal-guided ad- ministration of pharmaceuticals)—may include things such as the sustained-release bimatoprost (Bimatoprost SR, Allergan) and iDose (Glau- kos). "Each of those two systems have their limitations," Dr. Bacharach said. With iGAPS, efficacy is great, but there are safety concerns, he noted, adding that eGAPS tend to be safer but with an efficacy tradeoff. Innovative surface devices One device currently being explored is the Punctal Plug Delivery System (PPDS, Mati Therapeutics), according to Malik Kahook, MD. "The Mati plug fits in the tear drainage system and slowly elutes drug from the faceplate to the tear film in a passive manner," Dr. Kahook said. It is minimally invasive to insert and has the ability to deliver commonly used topical drops to the ocular surface, he noted. "Drawbacks include unreliable retention of the plugs, as well as the small medication loads that each plug can carry," he said. This also requires a robust tear film that can retain the drug. Evaluating surface-based sustained delivery platforms for glaucoma About the doctors Jason Bacharach, MD Medical director, founding partner North Bay Eye Associates Co-director, Glaucoma Services California Pacific Medical Center San Francisco Malik Kahook, MD Slater Family Endowed Chair in Ophthalmology Professor of ophthalmology Vice Chair for Translational Research Director, Glaucoma Service UCHealth Sue Anschutz Rodgers Eye Center Aurora, Colorado "In a perfect world, we would have an external device that is 100% retained and free of adverse events..." —Malik Kahook, MD

• Blank Page
• Blank Page (1)