EyeWorld Asia-Pacific March 2014 Issue

50 EWAP PHARMACEUTICALS March 2014 Setting cataract sights on Omidria by Maxine Lipner EyeWorld Senior Contributing Writer New agent may be added to balanced salt solution B alanced salt solution is a vital part of the cataract procedure, helping to irrigate away the nucleus during phacoemulsification. A drug pending FDA approval called Omidria (OMS302, Omeros, Seattle, Wash., U.S.) may bring a new dimension to this part of the procedure, according to Steve Whitaker, MD , vice president of clinical development and chief medical officer of Omeros. Omidria, which contains both phenylephrine, known to be a mydriatic, and the NSAID ketorolac, is added to the balanced salt solution at the start of cataract procedure, he explained. Unlike drops given preoperatively, this medication is irrigated through the eye throughout the surgery, something that is important, he said. “If the iris is irritated during the procedure, it releases prostaglandins, and prostaglandins can cause miosis,” Dr. Whitaker explained, adding, “The ketorolac inhibits the cyclooxygenase enzymes that produce prostaglandins, so ketorolac can block that irritation-induced miosis.” Going with the balanced salt solution flow Omidria is infused in the balanced salt solution throughout the procedure. “You always have a constant concentration of phenylephrine and ketorolac, and that’s happening at the time of the surgical insult,” Dr. Whitaker explained. “Whereas if you’re using preoperative drops when you turn on the balanced salt solution that does not contain OMS302, it washes out of the anterior chamber, removing the preoperatively delivered agents.” During the procedure, aspiration is used to suck the lens out, but also sucks out fluid in the anterior chamber. The end result is any preoperative drops are, likewise, washed away. Richard L. Lindstrom, MD , adjunct professor emeritus, University of Minnesota, Minneapolis, pointed out that one tactic practitioners currently rely on to handle the question of pupil constriction is off-label use of epinephrine. “Many of us will add epinephrine to our bottle (of irrigating solution) or inject epinephrine into the eye,” he said. But there are a variety of issues with this. Among these, Dr. Lindstrom stressed the fact that since this is an off-label use, there can be difficulties obtaining the medication and ensuring that you have the right one. “It’s non-preserved, and particularly since we’ve had issues with compounding pharmacies, many hospitals won’t allow us to doctor our bottles ourselves anymore; they require a pharmacy to do it,” he said. “It gets inconvenient and complicated and in some situations is actually impossible.” What’s more, Dr. Lindstrom contends that use of phenylephrine, which has alpha-adrenergic effects alone, is probably better for patients than epinephrine, which has a beta effect. “Epinephrine is what you would inject into the heart if someone had a cardiac arrest,” Dr. Lindstrom said. Meanwhile, to keep the pupil dilated, all that is needed is the alpha-adrenergic effect. “Our older patients would rather not have the potential side effects of epinephrine,” he said. No one in an ophthalmologist’s office administering drops uses epinephrine to dilate the pupil— they all use phenylephrine, he continued. When it comes to the non- steroidal ketorolac component of Omidria, Dr. Lindstrom explained that this plays several roles. “We have good evidence that non-steroidals, by blocking the effects of prostaglandins, help maintain pupillary dilation during the procedure,” Dr. Lindstrom said. “But they also reduce pain, discomfort, and inflammation.” While both are an asset during cataract surgery, Dr. Lindstrom views maintenance of pupil size as a key factor for keeping complications at bay. He said that in study after study it is the maintenance of pupil size that is most correlated with complications, with a decrease in diameter portending problems. “A surgeon wants a large pupil because the complication rate goes up significantly if the pupil is small or comes down during surgery,” he said. Promising results Results with Omidria in clinical trials have been promising. Dr. Whitaker cited a phase 2 study where patients were given either Omidria or placebo in addition to standard preoperative regimens that included mydriatic as well as anesthetic agents. “For patients that got [Omidria], in the clinical trials, their pupils stayed open and they had less postoperative pain compared to the balanced salt solution alone,” Dr. Whitaker said. Only 6% of those who received the Omidria during cataract surgery had an intraoperative pupil diameter of less than or equal to 6 mm as compared to 46% of controls, 35% who received ketorolac alone, and 22% of those