Development of 5-Substituted N-Methylmorphinan-6-ones as Potent Opioid Analgesics with Improved Side-Effect Profile

Table 3

Overview of the analgesic activity of 14-methoxymetopon (13) in various models of pain in rodents.

Pain model	Route	ED50	Potency versus morphine	Reference
Hot-plate test (mouse)
50°C	s.c.	54 μg/kg	24	[29]
52°C	s.c.	28 μg/kg	94	[14]
56°C	s.c.	30 μg/kg	28	[30]
Hot-plate test 55°C (rat)	s.c.	15 μg/kg	313	[25]
	s.c.	30 μg/kg	63	[30]
	s.c.	28 μg/kg	82	[14]
Tail-flick test (mouse)	s.c.	7.6 μg/kg	500	[31]
	i.c.v.	0.29 fg/animal	>1,000,000	[31]
	i.t.	0.31 fg/animal	>1,000,000	[31]
Tail-flick test (rat)	s.c.	7.2 μg/kg	250	[25]
	i.p.	40 μg/kg	125	[25]
Tail electric stimulation test (rat)	s.c.	30 μg/kg^a	167	[33]
Writhing test (mouse)
acetic acid	s.c.	7 μg/kg	99	[25]
PPQ	s.c.	9 μg/kg	44	[30]
Carrageenan-induced inflammatory pain (rat)	s.c.	20 μg/kg^a	100	[35]

^aSignificant effect.