Table 1.

ED₅₀ values and 95% confidence limits for the effects of Δ⁹-THC, CP 55940, and anandamide, alone and in combination with rimonabant, to decrease rate of operant responding

	ED50 in mg/kg (95% confidence limits)	Potency ratioa (95% confidence limits)
Agonists alone
CP 55940	0.10 (0.072–0.14)
Anandamide	3.86 (2.85–5.23)	vs. CP 39 (24–59)
Δ9-THC	7.54 (5.41–10.5)	vs. CP 74 (46–120)
Δ9-THC		vs. Anand 2.0 (1.2–3.1)
Rimonabant antagonismb
Δ9-THC alone	7.54 (5.41–10.5)
+Rimonabant (1 mg/kg)	12.7 (7.66–21.0)	1.7 (1.0–3.0)
+Rimonabant (3.2 mg/kg)	17.8 (11.0–28.8)	2.4c (1.4–4.1)
+ Rimonabant (10 mg/kg)	6.19 (2.79–13.7)	0.8 (0.4–1.6)
CP 55940 alone	0.10 (0.072–0.14)
+ Rimonabant (1 mg/kg)	0.46 (0.11–1.85)	4.6c (1.2–17)
+Rimonabant (3.2 mg/kg)	0.15 (0.09–0.23)	1.5 (0.8–2.6)
+ Rimonabant (10 mg/kg)	0.20 (0.067–0.63)	2.0 (0.6–6.7)
Anandamide alone	3.86 (2.85–5.23)
+ Rimonabant (1 mg/kg)	2.80 (1.74–4.51)	0.7 (0.4–1.2 0)
+Rimonabant (3.2 mg/kg)	1.50 (0.72–3.10)	0.4d (0.2–0.7)
+ Rimonabant (10 mg/kg)	2.83 (1.40–5.76)	0.7 (0.4–1.5)

^aPotency ratios and 95% confidence limits are the ED₅₀ values of agonist divided by the ED₅₀ value of CP 55940 or anandamide, and the ED₅₀ values of the agonists in combination with an antagonist divided by the ED₅₀ value of the agonist alone

^bAgonist dose–response data were expressed and analyzed as a percentage of the response rate following each respective dose of rimonabant alone

^cSignificant antagonism

^dSignificant increase in potency