By Clay Barbour ST. LOUIS POST-DISPATCH 11/02/2007
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Linda Webster, 52, left, talks with Greg Martin, right, of Advanced Neuromodulation Systems.
(Stephanie S. Cordle/P-D) |
St. Louis — Millions of Americans suffer from chronic pain so intense that they rely on the strongest pain relievers available to get them through the day. But over time, these drugs lose their effectiveness.
It's a vexing cycle that has plagued doctors for years. A patient complains of increased pain, the doctor increases the dose. Soon, that dose doesn't work, and the patient needs more.
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Now, researchers at St. Louis University have figured out how to prevent tolerance to morphine and other opiate narcotics. The discovery could lead to relief for many patients who have watched their dosages increase several times over, yet still suffer from severe pain.
"This would be huge," said Dr. Rick Marinelli, president of the American Academy of Pain Management. "It would stop escalating doses, make the current doses work better and limit the side effects patients get from too much pain medication."
Chronic pain costs an estimated $100 billion annually in the United States, and affects roughly a third of all Americans.
"Almost everyone who takes pain medication, even for a matter of weeks, develops tolerance," said Dr. Robert Swarm, Washington University's director of pain management. "For people on drugs for years, tolerance is a major problem. So this is exciting. It's a big step forward."
Using an animal model, the scientists discovered a substance interfering with the delivery of morphine. They found that repeated doses caused peroxynitrite to develop in the spinal cord, which in turn caused inflammation and damage to proteins and DNA in that area.
They also found that by manipulating the peroxynitrite they could prevent the patient from developing a morphine tolerance. This could be accomplished by giving the patient a combination of two drugs at once: the morphine and a drug to prevent the buildup of peroxynitrite.
The study was released Thursday in The Journal of Clinical Investigation. It is just the beginning of a long process, one that could take between five and 10 years before patients see the benefits of its findings. But medical experts agree it is significant.
"Now that we understand how tolerance works, it will have a remarkable effect on the management of pain," said Dr. Daniela Salvemini, who headed SLU's study.
Sometimes chronic pain is the result of a disease, such as cancer. Other times it comes from an injury. And in some cases, pain's origins are a mystery.
Douglas Sneed's chronic back pain started five years ago, during one of his bartending shifts. He was making a martini, turned to answer a question and felt a "snap."
Doctors have never been able to diagnose the cause. Instead they have tried to help Sneed, 37, manage his pain with drugs.
Over the years, Sneed's tolerance to the powerful narcotics has increased. This has led to larger doses, as well as the prescription of other medicines to deal with side effects. Increased doses of narcotic pain relievers can lead to respiratory problems, constipation, depression and addiction.
These days Sneed takes a cocktail of six different drugs daily, including percocet. He also stops by the pain management center at SLU once a month for injections.
"You start out with the pain meds and before you know it, you're taking a whole host of muscle relaxers and antidepressants," he said.
He has trouble working long hours and dealing with stress, and worries what the future holds if he continues taking medicine at this rate.
"It's a double-edged sword," Sneed said. "But what can you do? It's either deal with the side effects or deal with the pain."
cbarbour@post-dispatch.com | 314-727-6234
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