Table 1.

Affinities (K_i) and potencies (EC₅₀) at the κ opioid receptor.

	R	Ki ± SEM	EC50 ± SEM
		(nM)a,b	(nM)b,c
1		2.4 ± 0.4	1.8 ± 0.5
5		0.60 ± 0.07	0.40 ± 0.04
6		0.32 ± 0.02	0.14 ± 0.01
7		2.2 ± 0.6	5.2 ± 0.4
8		5.3 ± 1.7	20 ± 3.5
9		1.6 ± 0.5	4.2 ± 0.7
10		35 ± 15	108 ± 18
11		1.9 ± 0.5	3.8 ± 0.3
12		31 ± 8	75 ± 7
13		141 ± 29	320 ± 13
14		> 1,000	1,660 ± 60
15		147 ± 26	274 ± 16
16		13 ± 3	31 ± 8
17		50 ± 9	26 ± 6
18a		11 ± 1	10 ± 1
18b		6.6 ± 0.3	5.7 ± 0.7
19		72 ± 13	72 ± 5
20		4.0 ± 0.4	2.8 ± 0.3
	U50,488H	2.2 ± 0.3	1.4 ± 0.3

^aInhibition of [³H]diprenorphine binding to CHO-hKOR.

^bMean of three independent experiments performed in duplicate.

^cEnhancement of [³⁵S]GTPγS binding to CHO-hKOR. All compounds were full agonists (E_max = 81–106% relative to U50,488H).

^*configuration unknown.