A Food and Drug Administration advisory panel Friday endorsed competing injectable gels that combat facial wrinkles, smoothing the way for a big marketing showdown.

The panel recommended that the FDA approve Restylane by Medicis Pharmaceutical Corp. and Hylaform by Inamed Corp., collagen alternatives already available in Europe, Canada and Mexico.

Cosmetic surgeons have been eagerly awaiting approval of the gels — which enjoy an underground following in Los Angeles.

Dr. Brian Kinney, a plastic surgeon, said he had a list of 30 patients who wanted prescriptions as soon as Restylane or Hylaform were approved.

“I have seven or eight patients now who go to Mexico to get it,” he said.

The gels use hyaluronic acid, a substance that naturally occurs in the skin, to plump out creases and smooth facial scars. Inamed’s product is derived from ground rooster combs. Restylane doesn’t contain animal products.

Analyst Thomas Gunderson of US Bancorp Piper Jaffray said combined annual sales of the gels could rapidly climb to $150 million, about double current sales of collagen. Though Restylane is the leading gel outside the United States, Gunderson predicted the business would be split evenly between Medicis of Scottsdale, Ariz., and Inamed of Santa Barbara, Calif.

The stakes are high for both companies. Medicis has placed a big bet on Restylane, licensed from Q-Med, its Swedish developer. The company in its last fiscal quarter said expenses rose by $30 million, or nearly 40 percent, as it built its sales force for Restylane.

Inamed, meanwhile, is the leading marketer of collagen, long the mainstay in wrinkle smoothing treatments. The company, which also markets breast implants, recently launched human collagen as an alternative to collagen derived from cow tissue, which causes an allergic reaction in some patients.

Analysts believe that the gels will erode collagen sales.