Ocular tolerance, IOP effects of anti-inflammatories examined

Fort Lauderdale, FL-Both loteprednol etabonate 0.5% and tobramycin 0.3% ophthalmic suspension (Zylet, Bausch & Lomb) and tobramycin 0.3% and dexamethasone 0.1% ophthalmic suspension (TobraDex, Alcon Laboratories) were well tolerated in a recent study, but increases in IOP were seen in four times as many subjects in the TobraDex group as in the Zylet group, said Edward J. Holland, MD. (See related article on Page 28.)

According to results of the study of about 300 subjects, Zylet was non-inferior to TobraDex for a series of comfort and tolerability parameters and produced statistically significant improvement in pain scores in a study of about 300 patients.

Dr. Holland, director, Cornea Services, Cincinnati Eye Institute, and professor of ophthalmology, University of Cincinnati, Cincinnati, OH, explained that "non-inferior" is the term preferred by statisticians and epidemiologists to describe the results, which could also be interpreted to mean that the comfort and tolerability of the agents were equivalent in the two groups.

Research has shown that loteprednol, the steroid component of Zylet, has a lower risk of raising IOP than dexamethasone, the steroid found in TobraDex, or prednisolone, he added.

"That is why Zylet has been promoted as a safer steroid," Dr. Holland continued. "It has very good efficacy as an anti-inflammatory medication, but it is much safer than the other steroids in terms of raising IOP."

This study was one of the first to compare Zylet, the more recently approved combination agent, to the more established TobraDex, and to evaluate IOP as well as comfort and tolerability, he said.

Investigators observed increases from baseline IOP ≥10 mm Hg in both groups. The increase was measured in 1.95% of the subjects treated with Zylet and 7.48% of the subjects treated with TobraDex; the difference was statistically significant (p = 0.0280).

In this double-masked, multicenter, parallel-group clinical trial, 306 subjects were randomly assigned to receive either Zylet (n = 156) or TobraDex (n = 150) q.i.d. in both eyes for 28 days. Subjects were asked at each of six study visits about ocular comfort and tolerability through symptoms such as pain, stinging and burning, irritation, itchiness, foreign body sensation, dryness, and light sensitivity.

Comfort and tolerability were rated from 0 (extremely uncomfortable) to 100 (extremely comfortable) and obtained at study visits as well as through daily diary entries.

Results showed a statistically significant improvement in pain in the Zylet group in the mean change from baseline to the final week of diary assessments (p = 0.0071). A significant deterioration in light sensitivity (p = 0.0076) occurred in the TobraDex group.

Overall, Zylet was non-inferior to TobraDex for all comfort and tolerability parameters, and changes from baseline to each subsequent study visit revealed a statistically significant difference between the treatment groups favoring Zylet for all of these parameters (p = 0.0488).

The data were presented in a poster at the annual meeting of the Association for Research in Vision and Ophthalmology, Fort Lauderdale, FL.