Hyperthermia-free TRPV1 antagonists - new category of pain killers?

The transient receptor potential cation channel, subfamily V, member 1 (TRPV1), also known as the capsaicin receptor is a protein which in humans is encoded by the TRPV1 gene. This protein is a member of the TRPV group of transient receptor potential family of ion channels. TRPV1 is a nonselective cation channel that may be activated by a wide variety of exogenous and endogenous physical and chemical stimuli. The best known activators of TRPV1 are heat greater than 43°C,  pepper like chemicals  (capsaicin - most of us might have used gel containing capsaicin) and proton. The same channel is responsible for pain caused by these diverse stimuli. For a number of years scientists have focused on the development of TRPV1 antagonists, but have been stymied by the dangerous hyperthermia side effect.

Now researchers lead by  Dr. Andrej A. Romanovsky,  have come up with an explanation for the side effect and how one can avoid the side effect. 

Researchers found that the hyperthermic effect has the highest sensitivity to the extent of TRPV1 blockade in the proton mode (0.43 to 0.65) with no to moderate sensitivity in the capsaicin mode (–0.01 to 0.34) and no sensitivity in the heat mode (0.00 to 0.01). Hence they conclude that hyperthermia-free TRPV1 antagonists do not block TRPV1 activation by protons, even if they are potent blockers of the heat mode, and that decreasing the potency to block the capsaicin mode may further decrease the potency to cause hyperthermia. Researchers suggests that the  drugs that are being developed should be designed not to block the proton activation of TRPV1.

Scientists believe that this new generation of painkillers will be effective in treating pain related to a number of conditions including cancer, AIDS, migraines and diabetes. Let us hope some good news from these class of compounds....

Ref : Abstract of the paper