The Holy Grail of chronic pain is to eliminate the pain without impairing thinking, alertness, coordination, or other vital functions of the nervous system.

A study using a combination of capsaicin—the substance that makes chili peppers hot—and a drug called QX-314, was successful in blocking pain-sensing neurons in rats without impairing movement or other sensations such as touch. This finding suggests an improved way to treat pain ranging from childbirth to surgical procedures to chronic pain.

This finding shows that a specific combination of two molecules can block only pain-related neurons. Researchers believe that this approach shows promise for major breakthroughs in the future that will help millions of people who suffer disabling pain.

QX-314 is a derivative of lidocaine, which is a commonly used local anesthetic and works by blocking electric signals in all nerve cells. Using QX-314 alone cannot get through cell membranes to block their electrical activity. That is where capsaicin comes in.  Capsaicin opens the cell membrane pores that allows QX-314 to pass through the cell membrane and selectively block the cells’ activity.

It is using the the cell membrane that makes this study unique. Specifically, the cell membrane channel used is TRPV1, which is an ion channel that controls the flow of electrically charged ions in and out of cells. It is shutting down the electrical flow that stops the pain.

One problem with the combination of QX-314 and capsaicin is the potential for unpleasant burning sensations until the QX-314 takes effect. To minimize this problem the researchers administered QX-314 a few minutes before the capsaicin.