Synthesis and characterization of potent and selective mu-opioid receptor antagonists, [Dmt(1), D-2-Nal(4)]endomorphin-1 (Antanal-1) and [Dmt(1), D-2-Nal(4)]endomorphin-2 (Antanal-2)4395, Fichna, J., do-Rego J.C., Chung N.N., Lemieux C., Schiller P.W., Poels J, J. Broeck Vanden, Costentin J., and Janecka A.E. , J.Med.Chem., 8/2/2007, Volume 50, Issue 3, Number 520, p.512 - 520, (2007)