|Gabapentin Shown Effective for Fibromyalgia
New research supported by the National Institutes of Health’s
National Institute of Arthritis and Musculoskeletal and Skin Diseases
(NIAMS) shows that the anticonvulsant medication gabapentin, which
is used for certain types of seizures, can be an effective treatment
for the pain and other symptoms associated with the common, often
hard-to-treat chronic pain disorder, fibromyalgia.
In the NIAMS-sponsored, randomized, double-blind clinical trial
of 150 women (90 percent) and men with the condition, Lesley M.
Arnold, M.D., director of the Women’s Health Research Program at
the University of Cincinnati College of Medicine, and her colleagues
found that those taking gabapentin at dosages of 1,200 to 2,400
mg daily for 12 weeks displayed significantly less pain than those
taking placebo. Patients taking gabapentin also reported significantly
better sleep and less fatigue. For the majority of participants,
the drug was well tolerated. The most common side effects included
dizziness and sedation, which were mild to moderate in severity
in most cases.
NIAMS Director Stephen I. Katz. M.D., Ph.D., remarked that “While
gabapentin does not have Food and Drug Administration approval
for fibromyalgia1, I believe this study
offers additional insight to physicians considering the drug for
their fibromyalgia patients. Fibromyalgia is a debilitating condition
for which current treatments are only modestly effective, so a
study such as this is potentially good news for people with this
common, painful condition.”
Fibromyalgia is a chronic disorder characterized by chronic, widespread
muscle pain and tenderness, and is frequently accompanied by fatigue,
insomnia, depression, and anxiety. It affects three million to
six million Americans, mostly women, and can be disabling.
The precise cause of fibromyalgia in not known, but research suggests
it is related to a problem with the central nervous system’s processing
of pain. As with some other chronic pain conditions, people with
fibromyalgia often develop a heightened response to stimuli, experiencing
pain that would not cause problems in other people. Yet, unlike
many other pain syndromes, there is no physical evidence of inflammation
or central nervous system damage.
Although gabapentin has little, if any, effect on acute pain,
it has shown a robust effect on pain caused by a heightened response
to stimuli related to inflammation or nerve injury in animal models
of chronic pain syndromes. Researchers have suspected that it might
have the same effect in people with fibromyalgia. The new research,
published in the April 2007 edition of Arthritis & Rheumatism,
indicates the suspicions were correct.
Although the researchers cannot say with certainty how gabapentin
helps reduce pain, Dr. Arnold says one possible explanation involves
the binding of gabapentin to a specific subunit of voltage-gated
calcium channels on neurons. “This binding reduces calcium flow
into the nerve cell, which reduces the release of some signaling
molecules involved in pain processing,” she says.
How gabapentin improves sleep and other symptoms is less clear,
and there are probably different mechanisms involved in fibromyalgia
symptoms. “Gabapentin improved sleep, which is an added benefit
to patients with fibromyalgia who often report unrefreshing or
disrupted sleep,” Dr. Arnold says.
What is important is that people with fibromyalgia now have a
potential new treatment option for a condition with few effective
treatments. “Studies like this give clinicians evidence-based information
to guide their treatment of patients,” says Dr. Arnold.
The mission of the National Institute of Arthritis and Musculoskeletal
and Skin Diseases (NIAMS), a part of the Department of Health and
Human Services’ National Institutes of Health, is to support research
into the causes, treatment and prevention of arthritis and musculoskeletal
and skin diseases; the training of basic and clinical scientists
to carry out this research; and the dissemination of information
on research progress in these diseases. For more information about
NIAMS, call the information clearinghouse at (301) 495-4484 or
(877) 22-NIAMS (free call) or visit the NIAMS website at http://www.niams.nih.gov.
The National Institutes of Health (NIH) — The Nation's
Medical Research Agency — includes 27 Institutes and
Centers and is a component of the U.S. Department of Health and
Human Services. It is the primary federal agency for conducting
and supporting basic, clinical and translational medical research,
and it investigates the causes, treatments, and cures for both
common and rare diseases. For more information about NIH and
its programs, visit www.nih.gov.