Opioid binding profiles of new hydrazone, oxime, carbazone and semicarbazone derivatives of 14-alkoxymorphinans

Several hydrazone, oxime, carbazone and semicarbazone derivatives of 14-alk oxycodeinones and 14-alkoxydihydrocodeinones were synthesised [1] and chara cterised in in vitro radioligand binding assays in rat brain membrane prepa rations. The tested compounds show the highest affinity for the mu opioid b inding sites and most of them have agonist character. Subtype analysis of t he binding shows mu(2) specificity. However, some of these ligands are able to block partially (40-60%) the high affinity (putative mu(1)) opioid bind ing sites while all of them act as reversible ligands at the low affinity ( putative mu(2)) sites.