Table 1.

In vitro binding affinities and functional activities of Compound A at the human KOR.

	Opioid Receptor Binding (Ki, µM) a			[35S]GTPγS Binding, KOR b
	KOR	MOR	DOR	EC50 (µM)	% stim.	Ke (µM)
Compound A	1.35 ± 0.32	10.7 ± 4.7 c	- d	- e	- e	1.53 ± 0.38
U69,593	0.0019 ± 0.0004	n.d.	n.d.	0.011 ± 0.004	100	n.a.

^a Determined in radioligand competitive binding assays using membranes of CHO cell stably expressing the human KOR (CHO-hKOR). ^b Determined in the [³⁵S]GTPγS binding assay with membranes of CHO-hKOR cells. Efficacy (% stim.) is expressed as percentage stimulation relative to the maximum effect of the KOR full agonist U69,593 (as 100%). ^c Data from [50]. ^d No specific binding was detected at 10 µM in the radioligand binding assays using CHO-hDOR cell membranes. ^e No stimulation up to 10 µM. n.d. not determined. n.a. not applicable. Values are means ± SEM of at least three independent experiments performed in duplicate.