Table 4.

IC₅₀ values of esmethadone in presence of Mg²⁺

	Esmethadone IC50 in 1 mM MgCl2	Hill slope	Cell number
NR1-2A	63.1	1.06	2–8
NR1-2B	41.7	1.17	2–7
NR1-2C	28.4	1.49	2–8
NR1-2D	13.5	1.42	3–7

Experiments were conducted in whole-cell patch-clamp electrophysiology at a holding potential of – 60 mV. Esmethadone concentration–response curves were obtained via whole-cell manual patch-clamp recordings in the presence of sub-saturating 1 µM L-glutamate, 10 µM glycine, and 1 mM MgCl₂. Every clamped cell was assessed with a single concentration of esmethadone, and the cell number range indicates the minimum and the maximum number of clamped cells per concentration for each NMDAR subunit-expressing cell type. Esmethadone was found to be approximately fivefold more potent in blocking NR1-2D subtypes compared to NR1-2A subtypes. Fittings parameters for esmethadone were obtained from data shown in [28] and analyzed with GraphPad Prism v8.0