Challenges in drug discovery for overcoming 'dysfunctional pain': an emerging category of chronic pain.

'Dysfunctional pain', a type of chronic pain, is associated with a broad range of clinical disorders, including fibromyalgia, irritable bowel syndrome and interstitial cystitis. It is emerging as a serious issue due to the negative impact of inexplicable pain on quality of life, lack of effective therapies and health care cost. Although drug discovery efforts in pain research have so far focused primarily on inflammatory and neuropathic pain, this editorial attracts attention to dysfunctional pain research and discusses a possible fundamental framework for tackling this difficult issue. While dysfunctional pain is characterized by chronic widespread or regional pain symptoms and occurrence of pain amplification, underlying pathophysiologies remain to be identified. Thus, a pivotal step in future research would be the exploration of pathophysiological pathways, such as relevant molecular networks, which are responsible for dysfunctional pain. Utilization of developing technologies paves the way for the identification of underlying pathophysiologies and the development of effective drugs which would eventually solve the clinical issues associated with dysfunctional pain.