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Thomas S. May, M.A.Medical Writer |
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Skin Patch May Relieve Severe Pain After Shingles
Thomas S. May, Medical Writer
Introduction People who develop shingles --a painful blistering rash--sometimes suffer from a kind of continued severe pain called postherpetic neuralgia (PHN). PHN is often very difficult to treat, requiring powerful drugs that can have serious side effects and may not work well. But some studies suggest that there is a better option.
The US Food and Drug Administration (FDA) recently approved the use of a
drug-filled skin patch called Lidoderm (lidocaine hydrochloride) as a
treatment of PHN. Lidoderm is a simple treatment that eases pain in many
PHN patients without causing serious side effects.
Every year, shingles affects roughly 1 million people in the United States and millions more worldwide. It is sometimes called the "belt of roses from hell" because the disease causes a blistering, belt-shaped rash that usually brings severe pain with it. The pain is
PHN strikes 10-15% of shingles sufferers. Since shingles is caused by herpes zoster--the same virus that causes chicken pox--and because the virus remains dormant, or "asleep," in the body for life, anyone who has ever had chicken pox can get shingles. Most often, however, the disease affects people in their 60s, 70s, and 80s, or younger people suffering from cancer or another source of immune deficiency.
Most patients recover completely, but some go on to develop PHN, which
lasts for months or even years after the rash is gone. Advantages of New Therapy "To date, the treatment of PHN has relied on the use of tricyclic antidepressants, which represent the most comprehensively studied medications for this pain syndrome," according to an article in the journal Acta Neurologica Scandinavica. The authors of the article write that tricyclic antidepressants work well to lessen the pain of about 50% of PHN patients. Other treatment options include opioids (powerful sedatives similar to opium) and anticonvulsants (medications normally used to prevent involuntary muscle contractions).
These drugs often provide some relief from the excruciating pain of PHN,
but many people who take them have experienced unpleasant side
effects--especially the elderly on antidepressants--and some patients are
not helped by the drugs at all. It is difficult to treat PHN because the
condition often does not improve no matter what therapy doctors use.
But several studies have shown that Lidoderm works well, and very few of the patients who used it had serious side effects. For example, one study published in the Clinical Journal of Pain found that 81% of PHN patients reported "moderate or better pain relief" after using Lidoderm.
Lidoderm is a small (10 centimeters by 14 centimeters) patch made of an adhesive material containing 5% lidocaine that is attached to a polyester-felt backing. The patch provides pain relief without causing total numbness in the area where it's applied. "The main advantage of the lidocaine patch is that it is a 'topical analgesic,'" says Bradley Galer, MD, of the Department of Pain Medicine and Palliative Care at Beth Israel Medical Center, who is one of the study's authors. Topical analgesics are painkillers that are applied directly to the skin over the problem area. The medication doesn't get into the bloodstream, so patients using the patch have fewer side effects than those who take the same drug by mouth or by injection, Galer explains. In another study, which was published in the journal Drugs, the researchers reported that "treatment with [the] lidocaine patch resulted in a significant reduction in pain intensity and increased pain relief." The researchers also found that the lidocaine patch caused few problems. The most common was "mild skin redness or irritation at the application site."
This study confirmed the findings of some earlier research conducted by
Galer and his colleagues at Beth Israel Medical Center. In a 1999 study
they reported that "all 32 participants [treated with Lidoderm]
experienced significantly reduced pain intensity." The lidocaine patch was
the only treatment that "significantly relieved their pain and improved
their quality of life," Galer says. Results Questioned
Despite the positive results reported by several researchers, some experts
remain skeptical about Lidoderm. For example, Brian Alper, MD, of the
Department of Family and Community Medicine at University of
Missouri-Columbia, says there is no clear evidence that the lidocaine
patch works any better than a placebo treatment does.
Alper, who has just finished a systematic review of all published studies having to do with PHN treatment, found that the clinical studies on Lidoderm failed to show any benefit in the treatment of PHN. "I found the lack of evidence supporting benefit and the steps behind the scenes [regarding FDA approval] rather shocking," he says.
According to Alper, the FDA did not approve Lidoderm based on the results of the first studies the manufacturer submitted and made it run one more clinical trial to show that Lidoderm would work. "An 'enriched enrollment study' was then conducted among patients who had been successfully treated with lidocaine patches in the past," Alper writes.
Even though Lidoderm clearly worked for these "highly selected" patients,
that doesn't mean it will work equally well for all patients suffering
from PHN, according to Alper.
Thomas S. May is a medical
journalist based in Toronto, Ontario, Canada. He has a master's degree in
psychology from Simon Fraser University in Burnaby, British Columbia. Source: Medscape Health
Reprinted from Medscape Health for Consumers.
Thomas S. May is a Medical
Writer. Source: Medscape Health
Reprinted from Medscape Health for Consumers.
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