It raised concerns about the safety and efficacy of an injectable treatment produced by the Collagen Corporation, which is based in Palo Alto, Calif.

Cosmederm has licensed patent 5,716,625 to the Collagen Corporation of Palo Alto, Calif.

Nobody from the Collagen Corporation said anything about trying to bring down the price.

Jerry & Ketchum in New York has been awarded assignments from the Collagen Corporation and the Block Drug Company.

The Collagen Corporation vigorously denies the assertion.

The Collagen Corporation takes its name and has always made most of its money from a product that makes people look younger.

Agency officials said they took the action because the Collagen Corporation had failed to warn consumers that the substance might trigger allergic reactions and diseases in some people.

The products made by the Collagen Corporation are called Zyderm and Zyplast.

The Collagen Corporation, a biotechnology company in Palo Alto, Calif., received patents this week on two proteins that stimulate the body to produce cartilage.

The Collagen Corporation said there was no business reason for the recent share-price volatility and increased trading in its common stock.