Table 1.

ED₅₀ values and 95% confidence limits for nicotine, varenicline, and cytisine alone (n=13) and in combination with mecamylamine (Mec; n=8) or DHβE (n=8). Potency ratios and 95% confidence limits are the ED₅₀ values of varenicline and cytisine divided by the ED₅₀ value of nicotine, or the ED₅₀ values of the agonists in combination with an antagonist divided by the ED₅₀ of the agonist alone.

	ED50 (mg/kg)	95% Confidence Limits (mg/kg)	Potency Ratio	95% Confidence Limits
Agonists alone (n=13)
Nicotine	0.83	0.68-1.00
Varenicline	2.51	2.05-3.07	3.0	2.3-4.0
Cytisine	2.97	2.56-3.44	3.6	2.8-4.6
Mecamylamine antagonism (n=8)
Nicotine	0.73	0.59-0.91
+ Mec (1 mg/kg)	2.41	1.61-3.59	3.3a	2.2-4.8
Varenicline	1.96	1.44-2.67
+ Mec (1 mg/kg)	6.13	4.14-9.08	3.1a	2.0-4.9
Cytisine	2.72	2.25-3.30
+ Mec (1 mg/kg)	6.13	5.19-7.23	2.3a	1.8-2.9
DHβE antagonism (n=8)
Nicotine	0.93	0.75-1.15
+ DHβE (3.2 mg/kg)	1.66	1.13-2.45	1.8a	1.1-2.8
Varenicline	2.58	1.98-3.36
+ DHβE (3.2 mg/kg)	3.22	2.46-4.21	1.1	0.7-1.8
Cytisine	3.22	2.54-4.10
+ DHβE (3.2 mg/kg)	2.82	1.86-4.27	0.9	0.5-1.4

^asignificant antagonism.