Eyeworld

45 EW FEATURE November 2015 • Glaucoma medical treatment the system as well as the safety, he stressed. Dr. Novack finds that it takes about 3 years from when a glaucoma product enters phase 3 FDA trials until it can be approved. Dr. Kahook pointed out that there are compa- nies that are in phase 2 and phase 3 for long-term drug delivery using noninvasive approaches similar to punctal plugs. "If all goes well with those trials, there is the potential to see drugs on the market from a punctal plug standpoint in 2017– 2018," Dr. Kahook said, adding that there are other drugs that are being investigated as injectables, such as bimatoprost sustained-release (Allergan) and travoprost sustained release (Envisia, Triangle Park, N.C.), that are making steady progress toward FDA approval in the coming years. EW Editors' note: Dr. Kahook has finan- cial interests with Alcon (Fort Worth, Texas) and Allergan. Dr. Lewis has financial interests with Aerie Phar- maceuticals (Irvine, Calif.), Allergan, and Envisia. Dr. Novack has financial interests with Peregrine Ophthalmic. Contact information Kahook: malik.kahook@ucdenver.edu Lewis: rlewiseyemd@icloud.com Novack: gary_novack@pharmalogic.com Meanwhile, there are also chal- lenges with more invasive therapy, with questions lingering. Dr. Kahook thinks that more long-term data is needed to show that such depots continue delivering medication for months at a time with consistent lowering of IOP. "If I can give an injectable that delivers drug for 4 to 6 months, I think that's a big win," he said. "We just need more insight from ongoing clinical trials so we can make data driven decisions." Dr. Novack thinks that there are pluses and minuses to all of the long-term systems. He cited the popular prostaglandin analogues. "Unlike pilocarpine, which is the early one, there is a question about something I call, 'Is more better?'" Dr. Novack said. "We know from eye drops that twice-a-day prostaglan- dins are actually less effective than once a day." For long-term systems of prostaglandins, there is a question of whether this is going to be as effective as a pulsatile delivery such as eye drops, he explained. Dr. Lewis pointed out that pros- taglandins are the biggest agents in glaucoma right now. "The concen- trations [needed] are so low that you can get away with putting a small amount in there, but it lasts a long time," Dr. Lewis said. "Drugs that are less potent would take up so much more volume that you probably couldn't get much duration, so I think at least at this stage the prosta- glandins make more sense." Dr. Novack has been studying a subconjunctival liposomal nanopar- ticle formulation of the prostaglan- din latanoprost (Peregrine Ophthal- mic Pte Ltd, Singapore) together with Tina Wong, MD, PhD, Singa- pore National Eye Center. "We show a good pressure drop in patients for 3 months similar to what you might expect from an eye drop," Dr. Novack said, adding that this, how- ever, isn't a comparative study. Finding success Ultimately, to be successful, any of these long-term approaches needs to be able to deliver enough med- ication to last for several months, Dr. Novack thinks. He likens it to a backpacking adventure where travelers must take along a certain amount of food and supplies but can only carry so much at a time. "I think that most people would feel that you need at least 3 months of delivery from an injectable or an implanted system," he said, adding that this is how often patients feel it is worth coming into an ophthal- mologist's office and having such a procedure done. However, for a less invasive approach such as the ForSight Vision 5 Helios insert (Menlo Park, Calif.), which simply rests on the surface of the eye under the lids and slowly releases the drug bimatoprost, the length of time this would need to last could be less, he thinks. Dr. Kahook pointed out that the amount of efficacy demanded by these systems is congruent with the amount of risk. "If a punctal plug was available that ensures 100% adherence but that might be slightly less effective than some of the topi- cal drops that have 50% adherence, I'd be OK with recommending it for my patients—I think that's a good tradeoff," he said. "But for the more invasive approaches, I think they should have efficacy that's congru- ent with what is available on the market today." Gaining FDA approval for such long-term systems is slightly differ- ent than the pathway practitioners are familiar with for a new drug, Dr. Novack said. "If it's a delivery sys- tem of an already approved product, in the U.S. that's called a 505(b)(2) route," Dr. Novack said. "Typical- ly only one pivotal clinical trial is required for a 505(b)(2) as opposed to a 505(b)(1)." However, there are additional hurdles that must be surmounted in the 505(b)(2) route. While the active pharmaceutical ingredient is the same in these long- term systems, the product used for dispensing this is different. So in such cases it's important to assess the performance characteristics of 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 Kahook, MD

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