BAK-free preparation of antibiotic safe for patient use

New York-In a comparison study of two ocular antibiotics, one with and one without benzalkonium chloride (BAK), no microbial contamination was found in the contents of any of 250 bottles of medication tested following a week of postoperative patient use.

Only one bottle tip was positive for coagulase-negative Staphylococcus, and the results suggest that a BAK-free, fourth-generation fluoroquinolone antibiotic does not increase patient risk of bacterial contamination, said Michelle Rhee, MD, assistant professor, Mount Sinai Hospital, New York. She and colleague T.L. Kaiura, MD, were among the authors of a poster presented at the annual meeting of the Association for Research in Vision and Ophthalmology.

Investigators at the New York Eye and Ear Infirmary, New York, tested 125 bottles of gatifloxacin with 0.005% BAK (Zymar, Allergan) and 125 bottles of moxifloxacin without BAK (Vigamox, Alcon Laboratories Inc.). Patients who had undergone intraocular surgery had been instructed to use the drops every 4 hours for 1 week, after which the bottles were collected to determine the incidence of microbial contamination.

If turbidity was observed, isolates were subcultured and identified by standard methods.

"We found that there was no difference," Dr. Rhee said. "Not having the BAK didn't make a difference in the moxifloxacin. It did just fine, and the patients were not at a greater risk for contamination."

The only incidence of contamination was found on the tip of one bottle of moxifloxacin.

Since BAK can be particularly toxic to the ocular surface of some patients, one implication of the study is that a BAK-free antibiotic could be especially useful in such cases, Dr. Rhee said.

"It also opens the door for exploring other antibiotics and how they could do without BAK or how other new drops under development could do without BAK," she added. "For now, it's nice that we have the option of a BAK-free fourth-generation fluoroquinolone that is self-preserved and safe for patient use."