Interesting Reading (2001)

[Guest guest]

Less morphine may be more - combination of morphine and naltrexone

may provide greater pain relief - Brief Article

Science News, March 10, 2001

In mice, very low doses of morphine combined with even lower doses of

a drug that usually blocks morphine's effect can give greater pain

relief than higher doses of morphine alone, according to a report in

the January BRAIN RESEARCH.

Researchers tested pain sensitivity by measuring how long mice let

their tails remain in a hot-water bath. Stanley M. Crain and his

colleagues at the Albert Einstein College of Medicine in New York

showed that very low doses of morphine--one-tenth to one-hundredth

the normal dose--made mice more sensitive to pain than a mouse

getting no morphine. These results confirmed their earlier findings

showing that low doses of morphine increase the excitability of pain-

related nerve cells.

When the researchers gave mice both a very low dose of morphine and

an even lower dose of the morphine-blocking agent naltrexone, the

mice waited longer before flicking their tails out of the hot water

than when they were given the small dose of morphine alone. The

effect of the combined low-dose treatment was equivalent to that of

higher doses of morphine.

Low-dose morphine has both pain-triggering and pain-killing

properties, Crain says. He suggests that the low-dose naltrexone

blocks the morphine at nerve-cell receptors that trigger painful

signals without affecting its more familiar pain-killing role.

Continue articleAdvertisement

What's more, mice given the very low doses of morphine and naltrexone

daily showed reduced pain sensitivity for several days, Crain says.

Mice and people given typical doses of morphine often develop

tolerance to the drug, and their pain returns.

Unpublished studies using naltrexone to boost the effect of regular

doses of morphine in people " have shown very promising results, "

Crain says. A tantalizing possibility, he says, is that the low-dose

combination of naltrexone and morphine will work as well as full-

strength morphine, yet be less likely to induce tolerance. Crain is a

stockholder in a company conducting human trials of naltrexone-

morphine therapy.

--D.C

COPYRIGHT 2001 Science Service, Inc.

COPYRIGHT 2001 Gale Group

http://www.looksmarthighschool.com/p/articles/mi_m1200/is_10_159/ai_71

843760