Phenyl-substituted normethadone derivatives were synthesized and their affinity (IC50) for opioid receptors was determined by displacement of the specific binding sites of [H-3]sufentanyl on rat brain preparations. Substitution resulted in a decrease of affinity in-vitro. These results suggest that normethadone-like compounds may interact with the P subsite of the mu-opioid receptor and that the P subsite has a well-defined cavity shape of stringent dimensions.
Mbela, TKN., Poupaert, J., Cumps, J., Moussebois, C., Haemers, A., Borloo, M., & Dumont, P. (1995). Phenyl-substituted Normethadones - Synthesis and Pharmacology. Journal of Pharmacy and Pharmacology, 47(3), 237-242. https://hdl.handle.net/2078.5/83377 (Original work published 1995)