Newer fluoroquinolones preferred antimicrobial prophylaxis

November 1, 2004

The fourth-generation fluoroquinolones gatifloxacin 0.3% (Zymar, Allergan) and moxifloxacin 0.5% (Viga- mox, Alcon Laboratories) provide safe, potent, and broad-spectrum coverage against bacterial pathogens that are important in post-refractive surgery infections, and based on that profile should be considered the treatment of choice for antimicrobial prophylaxis in patients undergoing excimer laser refractive procedures, agree Daniel S. Durrie, MD, and William Trattler, MD.

Interested in providing their patients with the best possible protection against postoperative infection but without compromising the procedure's outcome, Dr. Durrie and Dr. Trattler independently undertook randomized, masked, contralateral eye-controlled clinical studies evaluating gatifloxacin and moxifloxacin as antimicrobial prophylactic agents in their perioperative medication regimens.

"The earlier-generation fluoroquinolones, including ofloxacin (Ocuflox, Allergan), ciprofloxacin (Ciloxan, Alcon), and levofloxacin (Quixin, Santen), have been widely used by refractive surgeons for infection prophylaxis. However, emergence of bacteria resistant to those agents is a growing problem, and they also lack activity against atypical mycobacteria, which have become important pathogens in post-LASIK infections," said Dr. Durrie, who has a private practice in Overland, KS, and is clinical associate professor of ophthalmology, Uni-versity of Kansas Medical Center, Kansas City.

"Resistance development is minimized with the fourth-generation fluoroquinolones because of their dual mechanism of antibacterial action, and they also demonstrate activity in vitro against some species of atypical mycobacteria," he continued. "Therefore, they would seem to be preferable for refractive surgery antimicrobial prophylaxis." However, while the fourth-generation fluoroquinolones had been demonstrated to be safe and effective in clinical trials of patients with bacterial conjunctivitis or undergoing cataract surgery, they had not been studied in the setting of refractive surgery.

Rationale for studies "The bar for safety is even higher for agents used in elective procedures, and before adopting a fourth-generation fluoroquinolone into routine use, it was necessary to establish its suitability in an appropriately designed clinical study," said Dr. Durrie.

Dr. Trattler also considered the fourth-generation fluoroquinolones to have advantages from an efficacy perspective. However, he was aware of some reports that moxifloxacin might be associated with slower corneal healing compared with gatifloxacin. Therefore, his main purpose for conducting a randomized clinical trial was to rule out any difference between the two fourth-generation fluoroquinolones in their effects on epithelial healing after LASEK.

"I had used both drugs in my refractive surgery patients and had not noticed any differences. However, I designed this more rigorous study to test the hypothesis that there would be no significant difference between the two medication regimens in the time to re-epithelialization," said Dr. Trattler, a corneal specialist at Miami's Center for Excellence in Eye Care, and a volunteer assistant professor, Bascom Palmer Eye Institute, University of Miami School of Medi- cine, Miami.

He performed bilateral LASEK in 30 patients who were also randomly assigned to the use of moxifloxacin in one eye and gatifloxacin contralaterally. However, his entire medication regimens, including the steroid, nonsteroidal anti-inflammatory drug, and lubricant, and antimicrobial, consisted of products from a single manufacturer-Alcon or Allergan. The Alcon regimen included moxifloxacin, prednisolone (Econo- pred Plus), diclofenac sodium (Voltaren), and Bion tears, and the Allergan regimen consisted of prednisolone (Pred Forte), ketorolac tromethamine (Acular), and Refresh Plus.