NIH Radio
Treatment Blocks Pain Without Disrupting Other Functions
Brief Description:
A combination of two drugs can selectively block pain-sensing neurons in rats without impairing movement or other sensations.
Transcript:
Schmalfeldt: Imagine. Pain relief with no disruption of your other functions. Relief for a toothache that doesn't numb your whole jaw. Anesthetic that doesn't result in an inability to move. Treatment for chronic, intractable pain that doesn't cause problems for your body's other systems. A compound that affects pain neurons and only pain neurons. A study funded by the National Institutes of Health showed that such a compound is not just the stuff of dreams. A research team has identified a combination of two drugs that can selectively block pain-sensing neurons in rats without impairing movement or other sensations such as touch. The team, headed by Dr. Clifford J. Woolf of Massachusetts General Hospital and Harvard Medical School and Dr. Bruce Bean of Harvard Medical School, tested a combination of capsaicin—the substance that makes chili peppers hot—and a drug called QX-314 on neurons in a Petri dish, and determined that it blocked the pain sensing neurons without affecting other nerve cells. The compound was then tested on rats which then showed no signs of pain and were able to move and behave normally.
Porter: It's a pretty clever approach that they took. And we were certainly really excited about the outcome in the animal studies and the potential for long-term outlook for human studies.
Schmalfeldt: That was Dr. Linda Porter, program officer for the National Institute of Neurological Disorders and Stroke, which—along with the National Institute of Dental and Craniofacial Research and the National Institute of General Medical Sciences—funded the study. Despite the hopeful results, Dr. Porter says there is much more studying to be done before such a pain-relieving compound could be made available to human patients.
Porter: Well, I assume the next step they'll take is to begin to look more carefully at what kind of dosing would have to be used in humans, how long-term the effects might be, so in the animal studies they've done, the pain relief lasts for two or three or maybe more hours. Questions with toxicity, with irritation, the mode of delivery. We're very excited about it and we're hoping this is something that will move along pretty quickly. The studies in the animals are looking to be very promising, so we're keeping our fingers crossed that this will move.
Schmalfeldt: One problem with the current compound, as you might expect given its chili pepper origin, capsaicin tends to cause a burning sensation when first administered. Scientists will search for alternatives to capsaicin that do the same thing without causing the burning sensation. They will also look for ways to prolong the pain relief and hope to eventually develop pills that will stop the pain signals without requiring injections. The study appeared in the October 4th edition of Nature. From the National Institutes of Health, I'm Bill Schmalfeldt in Bethesda, Maryland.
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