TABLE 1.

Binding affinity (K_i, nM ± SD, n=4–13), agonist efficacy (%) and structures of nicotine and α4β2 nAChR partial agonists

nAChR	Nicotine1	Varenicline1	Cytisine1	3-Bromocytisine2	CP-6019272	CP-6019324
α4β2 Ki (nM) efficacy (%)	16.1 ± 4.1 100	0.4 ± 0.1 22 ± 2.5	2.0 ± 0.2 6.5 ± 0.2	0.2 ± 0.2 50 ± 12a	1.2 ± 0.2 15.6 ± 1.6	21 ± 19 ND5
α3β4 Ki (nM) efficacy (%)	520 ± 120 100	86 ± 16 93.5 ± 1.4	480 ± 63 100 ± 3.8 3,a	3.6 ± 1.2 ND	102 ± 22 79.9 ± 12.5	21 ± 28 30.2 ± 3.4
Structure

Ki values were determined in purified receptors expressed in oocytes or HEK cells.

¹Rollema et al. 2010;

²Coe et al, 2005b; 2009; unpublished data;

³Mineur et al., 2009;

⁴Chatterjee et al, 2010

⁵Efficacy could not be determined due to insufficient signal amplitude at the highest test concentration

ND = Not determined.

Agonist efficacies are relative to ACh or nicotine (^a).