Elan Corp. plc will be ringing in the new year with another product approval, this time for the snail venom pain product, Prialt.

The FDA approved the drug (ziconotide intrathecal infusion) for the management of severe chronic pain in patients who need intrathecal (IT) therapy, and who are intolerant or refractory to treatments such as IT morphine, systemic analgesics and adjunctive therapies.

It's the second approval in two months for the Dublin, Ireland-based company, which, along with partner Biogen Idec Inc., of Cambridge, Mass., gained an FDA nod in November for the multiple sclerosis drug Tysabri (formerly called Antegren). (See BioWorld Today, Nov. 29, 2004.)

"We've got two Elan innovations approved in six weeks, both in therapeutic areas in which we've focused and which had unmet medical needs," said Anita Kawatra, Elan's vice president of corporate marketing and communications. "Our scientists are excited that patients will benefit from these products. It shows the strength of our pipeline, the strength of our people, and I think it bodes well for the future."

All in all, it's been a good year for Elan, which watched its stock price climb to double digits for the first time since 2002, a year in which the SEC initiated an investigation and the company announced a major restructuring plan. In October, the SEC wrapped up the investigation, and Elan agreed to pay a civil penalty of $15 million with no requirement to restate or adjust its historical financial results or information.

The company's stock (NYSE:ELN) closed Wednesday at $26.70, down 8 cents.

The Prialt approval was based on data from three Phase III trials involving more than 1,200 patients. The most recent trial was conducted in response to an FDA approvable letter received in 2001. The letter requested additional data using lower doses and a slower titration, which led to a third Phase III randomized, double-blind, placebo-controlled study conducted at 39 U.S. sites in 220 adults with opioid-resistant, severe chronic pain, mostly neuropathic.

Patients in the trial participated for up to nine weeks and were randomized to receive IT Prialt or placebo. The primary endpoint was measured by the Visual Analogue Scale of Pain Intensity score, which at week three showed statistically significant improvement in patients receiving Prialt vs. placebo (p=0.036). The mean dose at week three was 6.9 mcg per day. (See BioWorld Today, Jan. 8, 2004.)

"I think certainly there are a lot of people, both at our company and doctors and patients, that are very excited about having this treatment available, because there are many patients who are suffering from chronic pain that can't be relieved by morphine and other drugs," Kawatra told BioWorld Today.

The most frequently reported adverse events in the third Phase III trial were dizziness, ataxia, confusion and abnormal gait, and a comparable amount of Prialt and placebo patients discontinued the study. Elan intends to present the data at a major scientific pain meeting in 2005.

In the two previous Phase III trials, Prialt was found to significantly reduce severe chronic pain in a variety of opioid-resistant patients with neuropathic pain and pain related to cancer and AIDS. Results of the first study were published in the Jan. 7, 2004, issue of the Journal of the American Medical Association.

Severe chronic pain is defined as lasting longer than six months and can be caused by many things, including failed back surgery, injury, accident and other nervous system disorders. Elan estimates there are about 120,000 people in the U.S. with severe chronic pain that are potential candidates for IT treatment with Prialt. With the growing incidence of cancer-related pain and other kinds of pain, the figure could rise to as high as 300,000 patients, Kawatra said.

"There's a significant number of people for whom morphine does not help," she said. "They can't get out of bed. They can't work. They can't drive a car because their pain is so severe. To those people who suffer from this type of pain, it's an important new option."

Elan has data of patients being treated with Prialt for more than seven years and the company said severe psychiatric symptoms and neurological impairment can occur during treatment. The company advises that patients with a pre-existing history of psychosis not be treated with the drug.

The first new IT analgesic approved in more than two decades, Prialt was developed by Elan scientists and is part of a class of non-opioid analgesics known as N-type calcium channel blockers. It is the synthetic equivalent of a naturally occurring conopeptide found in the marine snail Conus magus. Prialt appears to work by blocking N-type calcium channels on nerves that transmit pain signals. Elan gained ownership of Prialt when it acquired Neurex Inc., of Menlo Park, Calif., in 1998 in a $741 million stock swap. (See BioWorld Today, April 30, 1998.)

Prialt is administered through implanted or external microinfusion pumps that release the drug into the fluid surrounding the spinal cord. The European approval for Prialt is pending and expected in the first quarter. Elan filed the marketing authorization application in May 2003, and received a positive recommendation in November.

Elan, which holds worldwide rights to Prialt, expects to announce pricing and launch the product in the U.S. in late January.

"I would say that over the next few years the market could grow from $150 million to $250 million per year in peak sales," Kawatra said of the U.S.

In contrast, analysts have said the company's other product, Tysabri, could reach $2 billion in peak sales.

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