NEW YORK, Dec 01 (Reuters Health) -- Gabapentin, a drug used to prevent
convulsions in
epileptic patients, is also an effective treatment for neuropathy -- pain
caused
by damaged or
diseased nerves, according to two reports published in The Journal of the
American Medical
Association for December 2.
Both studies were sponsored by Parke-Davis Pharmaceutical Research, the
manufacturer of
gabapentin, which is sold under the name Neurontin.
The standard treatment for neuropathy is one of the tricyclic antidepressants,
a
class of
antidepressants that also relieve pain. But physicians would like to have
alternatives available
because tricyclic antidepressants can cause bothersome or even dangerous side
effects in some
individuals, especially older patients and those with heart disease.
In the first paper, Dr. Miroslav Backonja of the University of Wisconsin at
Madison and
colleagues report that gabapentin relieved the pain associated with diabetic
peripheral
neuropathy that may affect as many as 45% of diabetic patients.
During the first 4 weeks of the study, 165 patients received either (an
inactive) placebo or
gradually increasing dosages of gabapentin -- up to 3,600 milligrams per day
if
tolerated,
regardless of whether the pain was relieved at lower doses.
Patients then received the maximum tolerable dosage for another 4 weeks.
At the end of the study, the average daily pain score was significantly lower
in
the gabapentin
group than in the placebo group, Backonja's team determined. Patients also
reported significant
improvements in mood and quality of life.
Three side effects -- dizziness, sleepiness and confusion -- were more
frequent
in the gabapentin
group than in the placebo group.
"Gabapentin is a promising new agent for use in patients with neuropathic pain
when therapeutic
options are limited, and offers advantages over currently available treatments
as a first-line
agent," the researchers conclude.
In an accompanying editorial, Drs. Phillip A. Low and Rose M. Dotson of the
Mayo
Clinic,
Rochester, Minnesota, argue that a tricyclic antidepressant is preferable to
gabapentin for most
patients with diabetic peripheral neuropathy because gabapentin costs more and
is apparently no
more effective.
Low and Dotson suggest reserving gabapentin for patients with diabetic
peripheral neuropathy
for whom the tricyclics are dangerous or poorly tolerated.
Dr. Michael Rowbotham of the University of California at San Francisco and
associates
conducted a similar study of 229 patients with postherpetic neuralgia -- the
intense pain that
follows acute herpes zoster infection, also known as "shingles."
Even after the infection resolves, the "burning" or "tearing" pain may persist
for months or years
in approximately 10% to 15% of patients, most commonly those who are 60 years
of
age or
older, Rowbotham and colleagues explain.
The research team found that, after 8 weeks of treatment, patients who took
gabapentin
improved significantly more than those who took a placebo, as measured by
average daily pain
score, other pain measures, and sleep.
Sleepiness, dizziness, problems with coordination, swelling and infection were
more common in
the gabapentin group than in the placebo group, but there were no
cardiovascular
or other
serious side effects.
"From the safety and efficacy evidence in our study, a strong case can be made
for considering
gabapentin as a first-line oral medication for management of (postherpetic
neuralgia) pain,"
Rowbotham's group concludes.
The editorialists, Low and Dotson, agree that gabapentin may prove to be the
drug of first
choice for those with postherpetic neuralgia, especially older patients.
SOURCE: The Journal of the American Medical Association 1998;280:1831-1836,
1837-1842, 1863-1864.