Chili Pepper, Botox Injections Help Ease Pain

Capsaicin Injections Soothe Osteoarthritis; Botox Helps Many Types of Pain

Medically Reviewed by Michael W. Smith, MD

April 5, 2005 (Boston) -- Injections of the active ingredient found in red-hot chili peppers may produce lasting pain relief in people withknee osteoarthritis.

And injections of Botox, the popular wrinkle-smoothing drug, may treat many painful ailments, say experts who presented evidence at the annual meeting of the American Pain Society in Boston.

Capsaicin Is Hot

When injected into knees of six people with severe osteoarthritis, 1,000 micrograms of capsaicin, the substance that gives chili peppers its heat and kick, reduced pain significantly more than placebo, the researchers showed.

Relief lasted up to five weeks. It's unclear if pain relief would have lasted longer because the patients were only followed for up to six weeks.

Though capsaicin is available in over-the-counter creams and rubs to treat pain, these agents are only mildly effective. Researchers hope that by injecting capsaicin directly into the arthritic joint, it may better numb the pain.

Approval a Few Years Away

The new capsaicin drug, called ALGRX 4975, is under development by AlgoRx Pharmaceuticals Inc. It would be several years before such a product would be available on the market if approved by the FDA.

"We anticipate that the effects will last for three months, but until the studies are done we will not know for sure," says researcher Beth Vause, executive director of clinical and regulatory operations at AlgoRx. She says the compound is also being tested in other types of pain such as nerve pain and postoperative pain.

In the study, the only side effect was brief, burning pain at the site of the injection.

Botox Not Just for Wrinkles

Botox is known to be great for wrinkles, but it also works against various conditions that cause pain. In one study of 37 people with a variety of painful disorders including diabetic nerve pain,temporomandibular joint disease, the wrist pain of carpal tunnel syndrome, neck spasms, and headache, one injection of Botox produced an average 68% decrease in pain lasting 8.5 weeks.

In this study, the Botox toxin was injected under the skin, not in the muscle or joint as it has been in studies of back pain. More studies are now under way, according to researchers from Anodyne Pain Care in Dallas.

In another study of 25 people whose back pain did not respond to surgery, one injection of Botox into the muscle produced pain relief spanning about three months.

Botox injections can cause muscle weakness. But in this study no weakness or other side effects were seen.

Botox may reduce the severity of muscle spasms when injected into a muscle. However, it's possible that Botox may have an unknown effect on pain when given as a skin injection.

"If it works, it's really pretty nifty because it has no systemic toxicity and the results can last for four to five months," says Eric M. Chevlen, MD, a pain medicine specialist at St. Elizabeth Health center in Youngstown, Ohio.

Long-Term Outlook Uncertain

"You have to look for long-term effects, and it's not clear that [these injectables] provide long-term effects," says Gregory Terman, MD, an anesthesiologist at University of Washington Medical Center in Seattle.

Show Sources

SOURCES: 24th Annual Scientific Meeting of the American Pain Society, Boston, March 30-April 2, 2005. Gregory Terman, MD, anesthesiologist, University of Washington Medical Center, Seattle. Beth Vause, executive director, clinical and regulatory operations, AlgoRx. Eric M Chevlen, MD, pain medicine specialist, St. Elizabeth Health Center, Youngstown, Ohio.

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