Table 2.

EF₅₀ values with 95% confidence intervals before and after seven-day treatment for each group. * Indicates confidence limits do not overlap with saline (Sal) within a given treatment period (before or after repeated treatment). ^# Indicates confidence limits do not overlap across treatment periods within a given drug dose.

		Before Repeated Treatment			After Repeated Treatment
		EF₅₀	Lower Limit	Upper Limit	EF₅₀	Lower Limit	Upper Limit
Saline	Sal	2.053	2.032	2.074	2.068	2.033	2.113
	Sal 2	2.065	2.019	2.106	2.064	2.039	2.092
	Sal 3	2.069	1.988	2.112	2.086	2.052	2.130
	Sal 4	2.083	1.978	2.147	2.096	2.075	2.116
NAQ	Sal	2.028	1.944	2.127	1.967	1.942	1.994
	0.1	2.019	1.997	2.045	1.986	1.940	2.023
	1	2.046	2.013	2.078	1.968^#	1.955	1.980
	10	2.055	2.036	2.076	1.954^#	1.938	1.972
Nalbuphine	Sal	2.028	2.008	2.045	2.024	2.005	2.043
	0.1	2.017	2.010	2.023	2.009	1.973	2.052
	1	1.995	1.982	2.008	1.941*^#	1.895	1.974
	10	2.013	1.963	2.049	1.971*	1.954	1.987
Buprenorphine	Sal	1.964	1.951	1.977	2.015	1.977	2.044
	0.001	1.978	1.958	1.999	2.016	1.990	2.048
	0.01	1.989	1.975	2.001	2.029	1.981	2.084
	0.1	ND	ND	ND	1.869*^#	1.835	1.897
Fentanyl	Sal	1.994	1.982	2.006	2.002	1.985	2.020
	0.0032	1.994	1.978	2.010	1.990	1.958	2.032
	0.01	1.956*	1.938	1.975	1.920*^#	1.913	1.926
	0.032	2.056*	2.023	2.109	1.885*^#	1.854	1.918
Methadone	Sal	1.991	1.967	2.013	1.992	1.980	2.004
	0.32	1.984	1.949	2.027	1.941*	1.913	1.966
	1	1.996	1.969	2.026	1.911*^#	1.906	1.916
	3.2	ND	ND	ND	ND	ND	ND
CP55940	Sal	1.998	1.961	2.033	2.059	2.049	2.07
	0.032	2.034	1.905	2.107	2.051	−inf	+inf
	0.1	2.118*	2.074	2.182	2.048	2.019	2.077
	0.32	ND	ND	ND	2.069^#	2.026	2.105
Amphetamine	Sal	2.003	1.991	2.014	2.026	1.976	2.077
	0.032	2.009	1.988	2.026	2.01	−inf	+inf
	0.1	1.946	1.815	2.023	1.957	1.935	1.986
	0.32	1.839*	1.791	1.917	1.876*	1.834	1.948