Combination antibiotic/steroid ideal for inflammation control

Fort Lauderdale, FL-Tobramycin 0.3% and dexamethasone 0.1% ophthalmic suspension (TobraDex, Alcon Laboratories) and loteprednol etabonate 0.5% and tobra-mycin 0.3% ophthalmic suspension (Zylet, Bausch & Lomb) both provide relief of punctate epithelial keratopathy. (See related article on Page 29.) However, the former combination drugs did so significantly faster, according to Francis S. Mah, MD, who reported the study results at the annual meeting of the Association for Research in Vision and Ophthalmology.

Because the outcomes with a combination of antibiotic and steroid are relatively under-explored, Dr. Mah and colleague Steven Rhee, MD, compared the efficacy of the two topical formulations for treating inflammation in blepharo-keratoconjunctivitis.

"The genesis of this study began with the release of Zylet about a year ago," Dr. Mah explained. He is assistant professor of ophthalmology, Eye and Ear Institute, department of ophthalmology, and medical director, Charles T. Campbell Ophthalmic Microbiology Laboratory, University of Pittsburgh School of Medicine, Pittsburgh. "The field of combination antibiotic and steroid drugs is a relative unknown, and the indications for an antibiotic-steroid combination are fairly limited. I use it for blepharo-keratoconjunctivitis and sterile ulcers."

He explained that the primary thrust of this study was to determine how rapidly the drugs resolved the symptoms of blepharo-keratoconjunctivitis.

"The patients were instructed to instill the drugs twice a day, which is different from the four-times-a-day dosing indicated for the drugs," Dr. Mah said. "Our primary purpose was to find a difference between the two drugs."

Dr. Mah pointed out that the study ran for only 3 to 5 days, which is not the length of time indicated for administration.

"Most likely, if the study had been 2 weeks long and if the drugs had been instilled four times a day, every patient would have had resolved symptoms," he added.

Besides the speed of resolution, Dr. Mah was also interested in testing the strength of the steroids in the formulations and determining if steroid-related complications developed with short-term use.

Twenty patients (40 eyes) were included in the study. All patients had to have at least moderate inflammation based on a scale of 3 (extensive components of blepharo-keratoconjunctivitis) to 0 (minimal components of blepharo-keratoconjunctivitis). At 3 to 5 days after the start of treatment, the ocular surface was graded again to determine the effect of the treatments.

"We found that using a lower dose of steroid and then following up in 3 to 5 days, there was a more rapid response of the symptoms of blepharo-keratoconjunctivitis with TobraDex compared with Zylet," Dr. Mah reported. Zylet was approved by the FDA in December 2004 and released during the first quarter of 2005.

The total ocular surface scores were perhaps the most telling. With a mean follow-up of 3.65 days, the ocular surface scores for Zylet and TobraDex were 3.4 and 1.8 (p = 0.002), respectively, with lower scores indicating better response.

Regarding the rapidity of the patient response, the dexamethasone is a stronger steroid.

"We hope these drugs are not being used long term," Dr. Mah added. "Our results showed that short-term use of these medications does not cause steroid-related complications when used to treat blepharo-keratoconjunctivitis, which is probably the primary indication."

He also pointed out that he uses TobraDex and any of the steroid-antibiotic combination drugs judiciously.