EyeWorld Asia-Pacific March 2020 Issue

PHARMACEUTICALS EWAP MARCH 2020 53 T hese days a variety of surface-based systems for delivering glaucoma medication to the eye are being explored 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 administration of pharmaceuticals)—may include things such as the sustained-release bimatoprost (Bimatoprost SR, Allergan) and iDose (Glaukos). “Each of Evaluating surface-based sustained delivery platforms for glaucoma by Maxine Lipner EyeWorld Senior Contributing Writer Contact information Bacharach: jbacharach@northbayeye.com Kahook: malik.kahook@cuanschutz.edu 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. 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 without anyone recognizing this, thereby affecting efficacy, Dr. Kahook continued. A third option, the bimatoprost ring (Allergan), 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-diameter 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 medial canthus, Dr. Kahook said. Yet another modality is the topical drug delivery device (TODDD, Amphorex Therapeutic), which Dr. Bacharach describes as similar to the ring. “This is a soft elastomeric structure 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 subconjunctival use of anecortave acetate This article originally appeared in the November 2019 issue of EyeWorld. It has been slightly modified and appears here with permission from the ASCRS Ophthalmic Services Corp. The Evolute Punctal Plug Delivery System (Mati Pharmaceuticals) is a surface device that fits in the tear drainage system. Source: Mati Pharmaceuticals