PL265 is an orally active dual enkephalinase inhibitor. PL265 is a prodrug of PL254, which can simultaneously and efficiently inhibit neutral endopeptidase (Neprilysin) and Aminopeptidase N. PL265 can effectively protect and significantly increase the local concentration of enkephalins (such as Met-Enkephalin and Leu-Enkephalin) released by cells at the pain or inflammation sites, thereby activating µ and delta opioid receptors to produce a potent analgesic effect. PL254 can also inhibit leukotriene A4 hydrolase (LTA4H), which may contribute to its additional anti-inflammatory effect by reducing the production of pro-inflammatory mediator leukotriene B4 (LTB4). PL265 can be used in non-addictive chronic pain research[1].