Though there have been substantial breakthroughs in the development of orally bioavailable treatments for neuropathic pain, each of these therapies is fraught with substantial side effects. The patient may achieve pain relief but at the price of significant interference with normal cognitive function, for example. Much data indicate that in many neuropathic pain conditions the signal that triggers pain actually arises at the level of the skin. Thus a biological rationale exists for the application of drugs to the skin involved in the neuropathic pain condition. The skin has been used extensively as an alternative means to deliver medications systemically, but there has been relatively little effort aimed at development of drugs to deliver to the affected/painful skin.
"In many neuropathic pain conditions the signal that triggers pain actually arises at the level of the skin."