August 16, 2005

Gabapentin reduces shingles pain

By Michelle Rizzo

NEW YORK (Reuters Health) - A single dose of gabapentin is
twice as effective as placebo in reducing pain and other
symptoms associated with shingles, according to the results of
a study published in the medical journal Neurology. Shingles is
a painful rash caused by re-activation in nerve tissue of the
chickenpox virus acquired earlier in life.

The inflammation and neuro-destructive effects associated
with shingles often produces severe pain, which is completely
disabling in some cases, coauthor Dr. Karin Lottrup Petersen
noted in comments to Reuters Health. Controlling this pain "is
an important medical problem on its own," she said.

Petersen and her colleague, Dr. James D. Barry, of the
University of California, San Francisco, studied 26 patients
with shingles-related pain. The team randomly assigned the
participants to a single 900-milligram dose of gabapentin or
placebo, and then switched them to the other treatment,
separated by at least 24 hours.

The researchers measured pain before treatment and at
30-minute intervals thereafter for 6 hours. All of the patients
completed the study.

Pain intensity decreased by a maximum of 66 percent in the
gabapentin group and 33 percent in the placebo group. The
authors note that the percent reduction in pain intensity was
greater with gabapentin at every time point from 1.5 through 6

"There was some evidence of carryover, so that patients who
received gabapentin at their first session still had some
reduction in pain at their second visit...2 days later,"
Petersen said. "This is well beyond the short duration of time
that gabapentin stays in the body, which is about 4 to 6
hours," she explained.

Petersen cautioned that this was a single-dose study using
a very high dose of gabapentin. "The patients were closely
monitored in our research center for at least 6 hours after
receiving the dose," she noted. "Physicians who wish to try
using gabapentin for their patients with...shingles pain should
start with a much lower dose."

SOURCE: Neurology, August 2005.