Long the standard of care in Europe, use of intracameral antibiotics with cataract surgery to prevent endophthalmitis is becoming more popular among U.S. surgeons as well. The change in strategy means added peace of mind that you're doing everything possible to keep the dreaded complication at bay. It also means a likely increase in case costs. Here's what you need to know.

There is no consensus on best practice for endophthalmitis prophylaxis. Other than the proven use of povidone iodine, no antibiotic protocol, whether it be topical or intracameral, has been definitively shown to be superior in a prospective, randomized, placebo-controlled clinical trial. But evidence in favor of intracameral has mounted to the point where around 50% (and counting) of U.S. surgeons consider it the best option. Most notably, a prospective study from the European Society of Cataract & Refractive Surgeons (ESCRS) showed a 5-fold decrease in endophthalmitis rate with intracameral antibiotic compared with topical antibiotic. What's hindering wider adoption? For now, experts say, the lack of an FDA-approved drug for intracameral delivery and the resulting fears of toxic errors committed at compounding pharmacies.

Surgeon preference

In this landscape, surgeons base their choice of antibiotic for intracameral injection on known effectiveness against endophthalmitis-causing pathogens and consideration of the breadth of what's been reported about safety and efficacy for this use. They're most likely to want to use moxifloxacin or cefuroxime. Vancomycin had also been a common choice until it was associated with extremely rare yet visually devastating post-operative hemorrhagic occlusive retinal vasculitis (HORV). When choosing an antibiotic, surgeons might also consider your facility's infection profile.

• Moxifloxacin. A popular off-label choice for intracameral injection is the commercially available, self-preserved formulation of moxifloxacin (Vigamox 0.5%, 3mL in a 4mL bottle). The simplest method: Draw 0.1mL of the solution (which is 0.5mg/0.1mL concentration) directly from the bottle, and it's ready to inject. Note that other branded or generic multi-use moxifloxacin formulations are not appropriate for this purpose.

Alternatively, if the surgeon prefers to inject a 0.25mg/0.1mL concentration, dilute the Vigamox 2-1 with BSS. A third approach, developed and reported by Steve A. Arshinoff, MD, FRCSC, associate professor in the Department of Ophthalmology & Vision Sciences at the University of Toronto, is to place the entire 3mL of Vigamox into a syringe and add 7mL of BSS. That results in a concentration of 0.15mg/0.1mL, which lets the surgeon inject more than 0.1mL, essentially replacing most of the aqueous with drug, without worrying that the concentration will be too high.

An important reminder: You can't use a multidose bottle for more than one patient, so you must either discard the unused portion or send the excess medication home with the patient, a sensible move if the patient will also need topical Vigamox to prevent, for example, a corneal infection following a limbal-relaxing incision, notes Sydney L. Tyson, MD, MPH, the CEO of Eye Associates SurgiCenter of Vineland (N.J.).

Using Vigamox for intracameral injection can get expensive, particularly if you waste most of each bottle. Undiscounted retail prices per 3mL bottle can range from $35 to $200. A no-cost option: Have the surgeon prescribe Vigamox for the patient, who then brings the bottle in on the day of surgery.

Now that intracameral injection is more popular, more compounding pharmacies are offering single-dose moxifloxacin. "This is available in unit vials containing 1mL, one vial per patient," says E. Helen Smith, RN, LHRM, CHOP, administrator at Largo Ambulatory Surgery Center at The Eye Institute of West Florida. "We currently pay $20 per dose/ patient. Nothing needs to be done other than the scrub tech drawing it from the vial into a 1mL syringe before the start of the case and placing a 27-gauge cannula just before the surgeon injects it into the anterior chamber."

The average price for single-dose moxifloxacin is around $20 per patient. Leiters Compounding Pharmacy quotes its price per vial as $21. Imprimis offers a box of 20 vials for $300 ($15 per vial). Some, but not all, pharmacies offer free shipping.

• Cefuroxime. Leiters and other compounders also offer single-dose cefuroxime for intracameral injection, often priced closer to $30 or $40 per vial or syringe. Keep in mind you could incur extra shipping costs for products that need to ship overnight because they need to be frozen. As always, it's important to choose a reputable, preferably 503B-designated, compounding pharmacy (osmag.net/EN2rBp).

You can also purchase cefuroxime powder, and then reconstitute and dilute it for intracameral injection. That is the preferred approach of Val Zudans, MD, the CEO of Florida Eye Institute and Florida Eye Institute Surgicenter in Vero Beach, Fla. His process, per the manufacturer's instructions: Add 7.5mL of preservative-free 0.9% saline (normal saline) to a 750mg vial of powder. Shake lightly and let sit for at least 1 minute. Draw 1mL of the reconstituted cefuroxime and transfer into a sterile empty vial. Add 9mL of preservative-free normal saline, which yields the proper concentration of 10mg/mL.

"You can transfer this, 1mL at a time, into single-dose vials, or you can draw up 1mL for a patient and discard the rest," says Dr. Zudans. "Through the entire process, nothing is exposed to the air. However, it's not a problem to discard all but one dose per vial given that the cost per patient is so minimal." Dr. Zudans buys his cefuroxime powder from Hikma Pharmaceuticals for $1.08 per vial. When the cost of saline and syringes is added, the cost per patient is around $2, he says.

No matter which drug or preparation option you choose, keep in mind that the simple reconstitution or diluting of a product immediately before patient use follows Joint Commission standards.

"The current definition of admixing or compounding for the ambulatory program is when 2 or more ingredients are combined together with a volume greater than 50mL," says Robert Campbell, PharmD, interim senior associate director pharmacist, standards interpretation, with The Joint Commission. "It's suggested that products prepared outside of a properly tested and certified compounding hood should be prepared and administered as quickly as possible and should never exceed 1 hour from the time of preparation until the start of administration."

A trend likely to continue

Many industry insiders predict that more and more U.S. surgeons will adopt intracameral antibiotics for cataract surgery. An ASCRS study known as TIME — "topical versus intracameral moxifloxacin for endophthalmitis prophylaxis" — could speed the adoption rate. The multicenter, prospective, randomized controlled trial, set to begin in around 6 months, will test whether unit doses of moxifloxacin designed for intracameral injection are more effective than topical administration.

"If intracameral moxifloxacin is shown to be superior, we'll seek FDA approval of the formulation," says ophthalmologist Eric D. Donnenfeld, MD, FACS, of Ophthalmic Consultants of Long Island in New York and Ophthalmic Consultants of Connecticut.

Beyond infection prevention, intracameral injection offers the added benefit of dropless surgery, which removes the challenge of patients complying with their dosing regimen.

"Once we became known as a dropless or fewer-drops center, people began to ask for us specifically," says Dr. Tyson. "Patients love the idea of not having to pay for or use drops. And for a bonus, our previously heavy burden of drop-related patient phone calls is gone." OSM