Hybridization of benzomorphan alkaloids with opioid peptide ''addresse
s'' is one of the successful method of modulation of receptor selectiv
ity and affinity of opioid ligands. In this paper we present biologica
l properties of two new compounds, hybridized naltrexone with Leu-D-Ph
e-NHNH2 or BrAc-Leu-D-Phe-NHNH2. These semicarbazides express signific
ant increase in affinity to delta receptors.