Treatment blocks pain without disrupting other...( A combination of two drugs can selec...)

A combination of two drugs can selectively block pain-sensing neurons in rats without impairing movement or other sensations such as touch, according to a new study by National Institutes of Health (NIH)-supported investigators. The finding suggests an improved way to treat pain from childbirth and surgical procedures. It may also lead to new treatments to help the millions of Americans who suffer from chronic pain.

The study used a combination of capsaicin the substance that makes chili peppers hot and a drug called QX-314. This combination exploits a characteristic unique to pain-sensing neurons, also called nociceptors, in order to block their activity without impairing signals from other cells. In contrast, most pain relievers used for surgical procedures block activity in all types of neurons. This can cause numbness, paralysis and other nervous system disturbances.

"The Holy Grail in pain science is to eliminate pathologic pain without impairing thinking, alertness, coordination, or other vital functions of the nervous system. This finding shows that a specific combination of two molecules can block only pain-related neurons. It holds the promise of major future breakthroughs for the millions of persons who suffer with disabling pain," says Story C. Landis, Ph.D., director of the National Institute of Neurological Disorders and Stroke (NINDS) at the NIH, which funds the investigators' research along with the National Institute of Dental and Craniofacial Research (NIDCR) and the National Institute of General Medical Sciences (NIGMS). NINDS and NIDCR are co-chairs of the NIH Pain Consortium. The study appears in the October 4, 2007, issue of Nature.*

Lidocaine, the most commonly used local anesthetic, relieves pain by blocking electric currents in all nerve cells. Although it is a lidocaine derivative, QX-314 alone cannot get through cell membranes to block their electrical activity.

That's where capsaicin co
'/>"/>