Good News for Pain Management
January 24, 2005
By: Hannah Clark for Body1
For the last four months, chronic pain patients have followed the news anxiously as problems surfaced for a number of popular pain medications.
In late September, Vioxx was taken off the market because data showed the arthritis drug increased risk of heart problems. In December, sales of rival Celebrex dropped in half after a study showed it could hurt the heart as well. A few days later, a study reported that naproxen, often sold under the brand name Aleve, increases heart risks in some patients by as much as 50 percent.
But help is on the way. There are no blockbuster drugs on the horizon that could help as many patients as Vioxx did. But the trove of painkillers is growing rapidly, and the next few years will see new medications that tackle pain in new ways.
That’s good news for the 50 million Americans who suffer from chronic pain – and for the pharmaceutical industry, which is ailing from a lack of new drugs in development. The worldwide market for pain medication is expected to double by 2010, to $75 billion a year, according to a report from Research and Markets.
“The pipeline is really robust and exciting,” said Dr. Russell Portenoy, chair of the Department of Pain Medicine at Beth Israel Medical Center in New York City.
He is most excited about a class of drugs known as “adjuvant analgesics,” pain medications originally developed to target another condition like depression or epilepsy. Twenty years ago, Dr. Portenoy said, doctors knew of only two adjuvant painkillers. “Now the list has over 50 drugs and it’s growing every year.”
One such new drug, Lyrica, was approved by the Food and Drug Administration late last year. Lyrica targets nerve pain, which is pain that exists in the nervous system rather than the body. When a person steps on a tack, Dr. Portenoy explained, a signal travels through the nervous system and tells the brain, “Get your foot off that tack.” Sometimes, however, a nerve can keep sending a pain signal even if the tack is nowhere to be found.
Another new drug, Prialt, also targets nerve pain, though it does not fall into the adjuvant category. Prialt blocks the calcium channels located on the edge of the spinal cord, thus short circuiting the pain message and keeping it from registering in the brain.
“Prialt is a targeted pain medication for patients that have failed pretty much all pain therapies,” said Dr. Michael Leong of the Bay Area Pain Center in California. Former Vioxx customers are not likely candidates for the medication, which must be administered with a pump under the skin.
But these drugs are just the beginning, according to Dr. Allen Burton, associate professor of pain medicine at M.D. Anderson Cancer Center in Houston, Texas. Pain research has only received serious attention for about two decades, he said, and it takes years for new discoveries to go through complicated human trials. “I think we’re going to see more and more pain medications that are targeting new receptors,” Dr. Burton said. He added,” It’s been a long slow process, but I think we’re finally getting there.”
Most pain medications fall into one of three categories: adjuvant analgesics like Lyrica; non-steroidal anti-inflammatory drugs (NSAIDs), which include ibuprofen, naproxen, and cox-2 inhibitors like Vioxx; and opioids like morphine and oxycodone.
Dr. Portenoy is less optimistic about the opioid pipeline. But he is hopeful about research into opioid antagonists, which can be taken along with opioids to cut down on side effects.
The NSAIDs in development are mainly cox-2’s, and doctors say patients should not dismiss them because of the Vioxx controversy.
“The public should not overreact,” Dr. Portenoy said. While Vioxx posed a legitimate risk, he said, the evidence against other cox-2’s, like Bextra and Celebrex, is not as strong. Bextra was found to be risky in already high-risk patients. Celebrex was found to be harmful when taken at high doses for an extended period of time.
Dr. Burton emphasized that all drugs have side effects. “The Vioxx story is very interesting because that drug helped a lot of people. It wasn’t all that toxic. In the media now you have the idea that this is like taking an arsenic pill.”
But he added, “They’ll remain extremely expensive because they’ll have to be so exhaustively tested now.”
Last updated: 24-Jan-05
|
