Neuropathic pain: new mechanisms of action of old drugs

Approximately 7–10% of the general population and 30% of cancer patients suffer from neuropathicpain, which is induced by the damage or disease of the neurologic structures. Sometimes neuropathicpain is caused by the pressure on a nerve but more often pain is due to the sensitization of the centers inthe spinal cord and brain. Some structures become so sensitive to the peripheral pain impulses that theybecome totally independent of them. Recently neuropathic pain is seen as an activation process of theinnate immunologic system. In this area the Toll-like receptors seems to play an important role and manydrugs are able to inhibit their activation. Treatment of neuropathic pain depends on the possibility of nervedecompression. However, in many cases, the sensitization is the target for treatment. For this purpose,most useful are gabapentinoids that inhibit influx of calcium across the membrane. Antidepressants (SNRI)such as duloxetine and venlafaxine are also useful as well as tricyclic antidepressants, although the latterare characterized by significant adverse effects. In some types of neuropathic pain 8% capsaicin, as well as5% lidocaine plasters or different opioids, are successfully used although there is still a lack of sufficient,good quality controlled clinical trials. The description of the role of Toll-like receptors in the pathophysiologyof neuropathic pain is a breakthrough in thinking and hope for the future to elaborate new, moreeffective treatment methods. Palliat Med Pract 2019; 13, 3: 123–12