Endo Pharmaceuticals Inc on Thursday said the US Food and Drug Administration confirmed it will require an additional clinical trial on Endo's extended-release painkiller, posing a significant delay to the drug's launch.
The FDA has criticised the way the company drew conclusions from two previous late-stage trials of the oxymorphone ER product because they included "data from patients who did not complete the trials," the company said.
The company said it hopes to complete a new trial and submit results to the FDA next year.
Endo's stock was down 92 cents, or 3.7 percent, at $24.14 in morning trading. Shares of Penwest Pharmaceuticals Co, which jointly developed the immediate-release tablet with Endo, were down $2.35, or 14 percent, at $14.40, also on the Nasdaq.
Endo already sells injectable and suppository versions of oxymorphone under the Numorphan brand. But those versions of the strong painkiller are used mainly in acute care settings for terminally ill patients who can no longer swallow.
A tablet version could be sold to far more patients, better positioning Endo to compete in the $3 billion-a-year US market for strong painkillers.
The FDA in October had asked Endo for the additional trial of the extended-release tablets, as well as a new trial of the immediate-release version.
Endo agreed to begin a short-term study of the immediate-release tablet, but had been hoping the FDA would reconsider its demand for a new trial of the extended-release tablet.
But the company on Thursday said the FDA held fast to its demand for the trial during a recent meeting with Endo officials.
"We remain confident that these products are safe and efficacious and will complement the already marketed injectable and suppository forms of oxymorphone," said Carol Ammon, Endo's chairman and chief executive officer.