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MEDICINE | IN THE LAB

Drug shows promise as treatment for fibromyalgia

Pregabalin slows the release of brain chemicals that may cause the chronic pain.

February 03, 2003|Linda Marsa | Times Staff Writer

Conventional medications, such as Tylenol, Motrin or even morphine, provide little relief to sufferers of fibromyalgia, a mysterious and debilitating pain disorder for which there is no effective treatment. But a new drug may be able to thwart the nerve signals that scientists now believe trigger the pain.

"This is a real breakthrough not only because it works, but it proves fibromyalgia can be treated," says Dr. Leslie Crofford, a rheumatologist at the University of Michigan in Ann Arbor who has studied the new drug, pregabalin.

The syndrome, which affects an estimated 5.6 million Americans, the majority of whom are women, is characterized by pervasive muscle aches and pain so intense that many people are unable to work or perform the simplest of tasks. Because the syndrome can't be diagnosed with conventional laboratory tests, such as blood tests or CAT scans, and is resistant to treatment, some physicians have thought that sufferers were hypochondriacs or simply depressed.

"Patients got a bad rap because doctors felt they didn't want to get better," says Crofford, "and that there was nothing that could make them get better."

The underlying cause of this condition is still unknown. But newer, more precise imaging tools can now map out the nerve pathways in the brain that are responsible for pain. This has given scientists some insights into why fibromyalgia sufferers are so exquisitely sensitive.

"The slightest sensory stimulation -- even being touched when putting on clothes -- can be highly painful in people with fibromyalgia," says Laurence A. Bradley, a fibromyalgia expert at the University of Alabama at Birmingham. "We suspect there are abnormalities in both the pain transmission and pain inhibition system."

Pregabalin reduces the release of specific brain chemicals, such as glutamate and noradrenaline, that may cause pain, says Terry Griesing, a neurology researcher with Pfizer Inc. in New York, the company that makes pregabalin. "This is our best understanding of what is happening," she says.

Early studies of the drug demonstrated that it was effective in controlling pain due to nerve damage, such as that suffered by people with shingles and diabetics with hand and foot pain. Because scientists suspect that fibromyalgia is caused by a similar mechanism, Griesing says, "the decision was made to test it for fibromyalgia."

In a recent eight-week study of pregabalin in 529 fibromyalgia patients, 29% of the pregabalin-treated volunteers reported at least a 50% reduction in pain, and their sleep quality and fatigue levels were significantly improved. Patients who took the highest doses of the drug had the best responses, Crofford says.

Pregabalin has already completed pivotal tests as a treatment for generalized anxiety disorder, nerve pain and epilepsy. Pfizer hopes to file for approval from the Food and Drug Administration for these uses within 12 months, according to a spokesman. The drug could be on the market as early as 2004. Once it's approved, doctors can also prescribe it for other conditions, such as fibromyalgia.

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