Lipo-Endomorphin-1 Derivatives with Systemic Activity against Neuropathic Pain without Producing Constipation Varamini, Pegah ; Mansfeld, Friederike M. ; Blanchfield, Joanne T. ; Wyse, Bruce D. ; Smith, Maree T. ; Toth, Istvan Abstract Publication: PLoS ONE Pub Date: August 2012 DOI: 10.1371/journal.pone.0041909 Bibcode: 2012PLoSO...741909V