. Author manuscript; available in PMC: 2012 Sep 1.

Published in final edited form as: Behav Pharmacol. 2011 Sep;22(5-6):548–557. doi: 10.1097/FBP.0b013e328349ab0d

Table 1. ED₅₀ values and their potency ratios for individual methadone isomers in rats tested in the warm water tail withdrawal procedure at 50°C and 55°C water temperatures.

Dosing condition	ED₅₀ mg/kg (95% CL) at 50°C	ED₅₀ mg/kg (95% CL) at 55°C	ED₅₀ potency ratio (55/50°C)
l-methadone	0.27 (0.2–0.4)	0.73 (0.6–0.9)	2.70
d-methadone	8.64 (3.4–21.7)	51.32 (32.4–81.2)	5.94
ED₅₀ potency ratio (d/l-isomer)	32.00	70.30	–

CL, confidence limits.

Table 1. ED50 values and their potency ratios for individual methadone isomers in rats tested in the warm water tail withdrawal procedure at 50°C and 55°C water temperatures.