“…The rational basis for this approach is the expression of opioid receptors outside of the central nervous system on peripheral sensory neurons, tissues and cells such as keratinocytes and fibroblasts [6], [7], [8], [9], [10] and the induction of potent analgesic effects by activating these peripheral receptors [11], [12], [13]. Moreover, following topical application [14], [15], [16], [17], adverse effects are reduced. Additionally, opioids also modulate cell proliferation and survival (Chen, Law et al 2008) and facilitate the wound healing and reepithelialization of skin wounds [9], [18] by stimulating keratinocyte migration [19], [20] as demonstrated repeatedly in vitro and in vivo .…”