Eyeworld

EW CATARACT 34 March 2019 by Maxine Lipner EyeWorld Senior Contributing Writer Pharmaceutical focus tion or an inflammatory disorder. "Investigators wanted to see if the patients who received the moxi- floxacin and got BAIT syndrome had underlying systemic disease that predisposed them to iritis," Dr. Arshinoff said, adding that investi- gators found that all of the patients had a predisposing disorder such as ankylosing spondylitis. Because the patients presented with the bilateral iritis after getting the moxifloxacin, the authors theorized that perhaps moxifloxacin was acting as a trigger in patients predisposed to iritis. Oral administration of moxi- floxacin achieves a much higher vitreous concentration of the drug than postoperative intracameral administration. The initial anterior chamber concentration of moxi- floxacin after intracameral admin- istration is, however, as high as the orally achieved vitreous levels, but quickly abates. It is possible that after administering the intracam- eral dose in a phakic eye that the high intracameral moxifloxacin dose became trapped behind the iris, in front of the human lens, and thereby triggered the BAIT-like syndrome. This has never been seen with operative administration of intracameral moxifloxacin after cataract surgery, where the IOL is not in contact with the iris, and the intracameral moxifloxacin rapidly abates from the initial injected level, Dr. Arshinoff said. Nick Mamalis, MD, profes- sor of ophthalmology, Moran Eye Center, University of Utah, Salt Lake City, pointed out that what made this recent case unique was that the BAIT-like syndrome was unilateral with intracameral moxifloxacin giv- en. "The previous cases of whatever causes this BAIT-like syndrome were associated with bilateral disease," Dr. Mamalis said. Also, while it has been associated with systemic moxi- floxacin, in only one investigation were some of the cases associated with intraocular moxifloxacin. He noted that the case involved a vitrectomy, not cataract surgery. "Usually when you have to do a vitrectomy, you give intravitreal antibiotics, but they gave intraca- meral moxifloxacin," Dr. Mamalis said. "The patient was fine initially in the postoperative period and developed this condition 3 weeks later." While it's always difficult incidence of cases of anterior cham- ber fibrin on postop day 1, some- thing he views as probably reflective of low-grade infection. Dr. Arshinoff said he has not seen a single such case among all 9,000 intracameral moxifloxacin patients. "The eyes are typically crystal clear the next day," he said. BAIT syndrome concerns A new case report 3 published in JCRS Online Case Reports pointed at one potential concern with intracameral moxifloxacin, a condition known as BAIT (bilateral acute iris transil- lumination) syndrome. In this case report, investigators described what happened to a patient who under- went vitrectomy for floaters. In one eye, the patient wasn't given any intracameral antibiotic prophylaxis and had no complications. "In the second eye, they gave the patient intracameral moxifloxacin in the anterior chamber, not in the vitre- ous, and the patient got unilateral BAIT-type syndrome," he said. Another study may also have implications here. Dr. Arshinoff cited an investigation 4 on those receiving moxifloxacin and other fluoroquinolone users to see if there was an increased risk of inflamma- decided to see what happened when they compared cefuroxime, van- comycin, and moxifloxacin rather than just concentrating on intra- cameral moxifloxacin alone. "Now that we have all three of them, we can compare them and look at their different lines of resistance," Dr. Arshinoff said. Of the three drugs, investigators found that moxifloxacin had the most to offer for endophthalmitis prophylaxis. "Moxifloxacin is the most effective drug with the biggest gap between the dose you have in the eye and the resistance levels of the targeted bacteria," Dr. Arshinoff said. If you look at how long this lasts in the eye, you can expect that the moxifloxacin should be effica- cious for about 40 hours after in- jection, under ideal circumstances. "But the other drugs, vancomycin and cefuroxime, at best last half as long," he said. When using the moxifloxacin intracamerally, Dr. Arshinoff finds that it's best to dilute it because this has a lower risk of toxicity. Even after using the agent in more than 9,000 cases, he has not seen any ad- verse effects with the moxifloxacin. Without intracameral antibiotics, many surgeons report seeing a low P ractitioners are always on the lookout for the most effective agents to keep endophthalmitis at bay following cataract surgery. Investigators led by Steve Arshinoff, MD, associate professor, Department of Ophthalmology and Vision Sciences, University of Toronto, Canada, considered the staying power of three of the most commonly used agents: cefuroxime, vancomycin, and moxifloxacin. In the study 1 , investigators developed mathematical models to calculate and compare the abate- ment rates of these three agents following intracameral administra- tion to determine how long they would be effective. "When you start to look at different antibiotics, you want to know how effective they are because perhaps last week's data shows that moxifloxacin is the safest drug, but then in another city, you get a bacterium that's highly resis- tant to moxifloxacin," Dr. Arshinoff said. "You want to use something else in the region of the resistant strain, but how do you know what to use?" Weighing abatement profiles By calculating abatement profiles on the relative duration of efficacy of the three agents, investigators were able to generate graphs and determine the best drug to use. In the case of new agents, investigators thought that it would be important to know how long they last in the eye, how much the patient actu- ally gets, what the concentration is, and how the drug abates. With abatement profiles, it is possible to compare the agents and determine what you're getting with each, Dr. Arshinoff noted. One issue with such profiles, however, is the need to generate constants of anterior chamber abate- ment since taking hourly objective measures is not feasible. Dr. Arshi- noff said that in a study 2 on intraca- meral moxifloxacin, he and fellow investigators mentioned that the numbers would be prone to being updated as they got better data for various rates. In the recent study, investiga- tors refined the numbers slightly and expanded on the framework. With more data collected for the drugs for the past 2 years, they Examining prophylactic intracameral antibiotics In a recent study, investigators looked at intracameral injections of cefuroxime, vancomycin, and moxifloxacin to help keep endophthalmitis at bay. Source: Steve Arshinoff, MD

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