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Small Vexol-Flarex comparative study disputed
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NEW YORK—Flarex (fluorometholone acetate 0.1%, Alcon) was equivalent to the new steroid, Vexol (rimexolone, Alcon), at controlling post-cataract surgery inflammation in a 50-patient study.
"I really was surprised," said Calvin Roberts MD, of his results. He said Vexol is supposed to work as well as Pred Forte (prednisolone acetate, Allergan) without raising IOP.
Fifty patients studied
Roberts performed phacoemulsification on 50 patients late last year, randomly assigning half to use Vexol and the remainder to use Flarex following surgery. No drugs were given before surgery; ofloxacin drops were given postoperatively.
Cell and flare readings were taken with the Kowa instrument 1 day postoperatively and again at 1 week and 1 month following surgery. The examination was masked as to which drug was being used, Roberts said.
None of the three sets of readings of Flarex and Vexol patients differed statistically, Roberts reported.
The mean measurement at 1 day was 28.75 photons/ms for the Vexol group and 28.10 for the Flarex group. It was 24.60 at 1 week for Vexol and 22.89 for Flarex; at 4 weeks, the mean score was 15.75 for Vexol users and 12.45 for Flarex patients.
| Vexol | Flarex | |
|---|---|---|
| 1 day post-op | 28.75 | 28.10 |
| 1 week post-op | 24.60 | 22.89 |
| 4 weeks post-op | 15.75 | 12.45 |
In the study, Vexol did not raise IOP after 1 month of use.
The 3-month study began in October 1995.
Conclusions surprising
"We, like Dr. Roberts, are surprised by the conclusions of this study," said Stella Robertson PhD, vice president for Clinical Research at Alcon, of Fort Worth, Texas.
"I feel that post-marketing studies of new products are valuable, but conclusions from relatively small studies have the potential to confuse issues like clinical efficacy and relative potencies of two drugs. It is possible, perhaps likely, that this is what happened in Dr. Roberts' study," she said.
Robertson cited the small size of the study group and the fact that Roberts enlisted patients without post-surgical inflammation as among her concerns about the new research. The firm's two post-surgical studies enlisted the help of 357 patients with significant inflammation.
Roberts is a professor at Cornell University, has an ophthalmology practice at New York Hospital and is a paid consultant for Ciba Vision. He responded to Alcon's comments by saying, "Their studies were comparing Vexol to a placebo for cataract inflammation. This is the first study to compare Vexol to any other steroid."
Roberts added that his is the first study of Vexol that was not funded by Alcon.
"Alcon has never compared Vexol to Flarex so it cannot comment on the relative potency of the two drugs," Robertson said. Both drugs, however, had separately received standardized potency tests, she said.
Uveitis treatment is the best measure of steroid potency, Robertson said. Double-masked, double-blind trials with 245 patients found Vexol as powerful as Pred Forte in treating uveitis, she said, a claim the Food and Drug Administration allows.
Roberts, who was "disappointed" by the results, finds no reason to switch to Vexol and will return to using Voltaren (diclofenac sodium, Ciba Vision Ophthalmics) as his preferred drug for post-cataract surgery inflammation.
Inconsistent results
Kerry K. Assil MD, of the Sinskey Eye Institute, Santa Monica, Calif., was one of the original FDA investigators. "These results would appear inconsistent with a series of prior multicenter masked trials evaluating the relative potencies of rimexolone with fluorometholone. Additional clinical studies from other centers will hopefully resolve inconsistencies," he said in a written comment.