Table 3.

ED50 values (95%CL) for fentanyl and SNC162 alone or in combination in assays of schedule-controlled responding and thermal nociception (50 and 54°C).

Drug or Drug Mixture	Fentanyl	SNC162
Schedule-controlled responding
Fentanyl Alone	0.0053 (0.0016–0.0171)
SNC162 Alone		0.92 (0.39–2.15)
59:1 SNC162/Fentanyl	0.0059 (0.0011–0.0307)	0.35 (0.07–1.8)
176:1 SNC162/Fentanyl	0.0027 (0.0018–0.0041)	0.48 (0.32–0.73)
528:1 SNC162/Fentanyl	0.0023 (0.0008–0.0065)	1.24 (0.44–3.44)
Thermal nociception (50°C)
Fentanyl Alone	0.012 (0.010–0.015)
SNC162 Alone		Inactive
59:1 SNC162/Fentanyl	0.009 (0.006–0.013)	0.53 (0.37–0.75)
176:1 SNC162/Fentanyl	0.004 (0.002–0.008)*	0.70 (0.36–1.33)
528:1 SNC162/Fentanyl	0.009 (0.003–0.025)	4.61 (1.60–13.29)
Thermal nociception (54°C)
Fentanyl Alone	0.026 (0.018–0.036)
SNC162 Alone		Inactive
59:1 SNC162/Fentanyl	0.019 (0.016–0.023)	1.11 (0.93–1.34)
176:1 SNC162/Fentanyl	0.017 (0.012–0.024)	3.01 (2.15–4.21)
528:1 SNC162/Fentanyl	0.021 (0.010–0.046)	11.06 (5.03–24.3)

^*Indicates that ED50 value for fentanyl or SNC162 in a drug mixture was different from ED50 value for fentanyl or SNC162 alone.