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Treatment for Pain

Endo Files Responses to FDA's Approvable Letters on NDAs for Oxymorphone ER and IR Tablets

CHADDS FORD, Pa., December 22, 2005 -- Endo Pharmaceuticals Inc., a wholly owned subsidiary of Endo Pharmaceuticals Holdings Inc. , today announced that it has filed what it believes are complete responses to the U.S. Food and Drug Administration's (FDA) approvable letters on the company's New Drug Applications (NDAs) for each of its investigational products oxymorphone extended-release (oxymorphone ER) and immediate-release (oxymorphone IR) tablets. As previously disclosed on October 20, 2003, the FDA issued approvable letters for oxymorphone ER and IR tablets but had requested that Endo address certain questions and provide more clarification and information, including data from additional clinical trials to further confirm the safety and efficacy of these products.

Under the Prescription Drug User Fee Act (PDUFA) guidelines, the FDA has 60 days to decide if today's submissions meet its criteria for a complete response and, if so, the company expects that the FDA will issue an action letter for each NDA no later than 180 days from today.

"We look forward to working with the FDA to bring both of these products to market," said Peter A. Lankau, president and chief executive officer. "We believe that oxymorphone is the most extensively studied oral opioid, including a data set of more than 3,000 patients. We also believe oxymorphone ER will give physicians an important new option for treating patients with moderate-to-severe chronic pain who require around-the-clock opioid therapy for longer than a few days." He noted that oxymorphone ER is the only opioid analgesic to have been studied in two placebo-controlled, 12-week trials in both opioid-naive and opioid-experienced patients and to have demonstrated statistically (p<0.0001) and clinically significant efficacy in these patient populations. "In addition, oxymorphone IR has been well studied for the treatment of acute moderate-to-severe pain, and we see it as a valuable complement to the extended-release formulation, as is our current intravenous formulation for hospital use," Lankau added.

"If approved, Endo will be prepared to launch oxymorphone ER and IR in the second half of 2006," Lankau said. Oxymorphone ER would compete in the market for long-acting, strong opioids, a $4.2 billion market in 2004.

To meet the FDA's request for more clinical information for oxymorphone ER, Endo conducted two separate multi-center, randomized, double-blind, parallel group trials evaluating this product in two distinct groups of patients with chronic low back pain: opioid-naive and opioid-experienced. The trial involving opioid-naive patients was conducted under the FDA's Special Protocol Assessment (SPA) process.

The company also reported that today's filing included previously disclosed positive results for a placebo-controlled, multi-center Phase III trial for oxymorphone IR in the treatment of acute post-operative pain. Endo also conducted this study under the FDA's SPA process. The data from the two new oxymorphone ER Phase III studies and from the one oxymorphone IR Phase III study will supplement the previously submitted Phase III trials for both products that the company believes the FDA already has accepted as demonstrating efficacy in the intended patient populations.

About Oxymorphone

Oxymorphone ER is a semi-synthetic mu-opioid agonist that has been formulated as a 12-hour extended-release tablet using Penwest Pharmaceuticals' proprietary time-release technology, TIMERx(R) delivery system. Oxymorphone ER has been studied in a wide range of chronic pain conditions, including low back pain, osteoarthritis pain, post-surgical pain and cancer pain. Oxymorphone ER is currently under review by the FDA. The safety and efficacy of oxymorphone ER have not been established by the FDA.

Oxymorphone IR has been studied in post-surgical pain in doses varying from 5 to 20 mg. Oxymorphone IR is currently under review by the FDA. The safety and efficacy of oxymorphone IR have not been established by the FDA.

Oxymorphone is a Schedule II controlled substance.

Respiratory depression is the chief hazard from all opioid agonists including oxymorphone preparations. Respiratory depression is a particular potential problem in elderly or debilitated patients as well as in those suffering from conditions accompanied by hypoxia or hypercapnia when even moderate therapeutic doses may dangerously decrease pulmonary ventilation. The most common adverse reactions reported by patients treated with oxymorphone ER during clinical trials were nausea, constipation, dizziness, pruritus (itching), vomiting, somnolence, increased sweating, sedation and headache.

Source: Endo Pharmaceuticals Inc.

Posted: December 2005

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