May 8, 2006 -- It might be possible to use antiviral drugs to reduce shinglesshinglespain, researchers report.
Dianna Quan, MD, and colleagues studied 15 patients with moderate to severe
shingles pain (postherpetic neuralgia). The condition stems from the
reactivation of the varicella-zoster virus.
The varicella-zoster virus causes chickenpoxchickenpox. Afterward, it lies dormant in the
body's nervous system. If the virus reactivates later in life, it can cause a
rash and pain, a condition commonly called shingles
since the rash appears in a band-like distribution.
Shingles pain usually resolves within four to six weeks but can last for
months and years. "As many as one million Americans are affected," write Quan
and colleagues, citing statistics from other researchers.
Quan's study appears online in the Archives of Neurology.
Quan works in the neurology department at the University of Colorado Health
Sciences Center in Denver. Participants in her study got a two-pronged
antiviral drug plan.
"If chronic pain reflects active infection, then antiviral therapy may help
patients with PHN," the researchers write. Post-herpetic neuralgia (PHN) is the
medical term used to describe the pain complication from shingles.
A large study could test that theory. But such studies are "time-consuming
and expensive," write Quan and colleagues. As a trial run, they studied a small
group of patients with shingles pain to see if the antiviral drug strategy held
Participants were at least 50 years old. They had moderate to severe
shingles pain that had lasted for at least three months.
First, the patients rated their shingles pain on a scale of 0-10. A rating
of 0 was for no pain; 10 marked the worst possible pain. Participants' average
score was 5 when the study started.
Next, the patients received IV doses of the antiviral drug Zovirax (acyclovir) every eight hours for 14 days, followed by
oral doses of another antiviral drug, Valtrex (valacyclovir), three times daily for one month.
Participants rated their shingles pain immediately after completing Valtrex
treatment, and again a month later.
Shingles Pain Dropped
Eight patients -- 53% -- had their shingles pain scores drop by at least two
points after antiviral treatment. The researchers call that decline a
"clinically significant reduction in pain."
People sometimes respond favorably to any treatment, so researchers often
compare active treatments to sham treatments (placebo). No placebo treatments
were tested in Quan's study.
The researchers don't know how the patients would have responded to a
placebo. They also can't rule out the possibility that shingles pain improved
for reasons unrelated to the antiviral drugs.
However, patients' self-reported improvement in shingles pain probably
wouldn't have happened spontaneously. The effect also seems to beat placebo
response in other studies, according to the study.
A larger trial of the antiviral drugs is warranted, write Quan and
Reported Side Effects
Of the 15 patients who started the study, five left the study early. One
patient couldn't tolerate multiple IV catheter insertions. Another had a rise
in blood levels of creatinine, which can indicate kidney problems, while taking
Zovirax. This returned to normal levels when the medication was stopped.
A third patient developed a respiratory infection which was then complicated
by aggravation of a pre-existing condition of atrial fibrillationatrial fibrillation (heart rhythm irregularities) and elevated liver enzymes while taking the Zovirax. "These events
were not likely related to acyclovir," write Quan and colleagues.
Two other patients left the study while taking oral Valtrex. One of them had
unexplained difficulty breathing; the other reported feeling nauseous, tired,
and ill. "These symptoms disappeared when valacyclovir was stopped," the