A panel of medical experts on Friday said a proposed eyedrop drug by River Plate Biotechnology Inc. isn't safe and effective enough to treat patients with dry-eye disease.

The panel of medical experts voted six to one against River Plate's Rejena eyedrop product. The Food and Drug Administration will take the panel's thoughts into consideration when making a final decision on whether to approve the drug.

Privately held River Plate is seeking FDA approval to use Rejena to treat dry-eye disease, which affects about 5 million people in the U.S., the company said. If approved, Rejena would be marketed by Alcon Inc. (ACL), a large Switzerland-based eye-care company.

Panel members expressed concerns about two trials the company presented, saying the trials weren't substantive enough to prove the product was effective.

Panel member Allen Rutzen, an eye specialist from Severna Park, Md., voted in favor of Rejena and said it just barely met the standards for approval. "Although I'm not overly impressed with the data," the drug did meet standards for approval, Rutzen said in explaining his position.

FDA officials had said in briefing documents ahead of the meeting that they questioned the robustness of one of the company's studies.

Panelists reiterated those concerns, and had additional questions about a second study the company submitted to the FDA for Rejena. "I found the first study to be invalid and in the second the design was flawed," said panel member Susan MacDonald, the director of ophthalmology at Tufts University School of Medicine.

-By Jared A. Favole, Dow Jones Newswires; 202-862-9207; jared.favole@dowjones.com