CO-NH2 CO-NH2 „„CO-NH2 CO-NH2

12 METHADONE, MORPHINE, PETHIDINE AND CODEINE
TABLE III—"ANALGESIC" POTENCY RATIOS OF METHADONE, MORPHINE, PETHIDINE AND
CODEINE AS DETERMINED BY S.C. INJECTION IN MICE AND RATS
IN FORTY-SIX DIFFERENT EXPERIMENTAL CONDITIONS
Methadone : morphine
Morphine : pethidine
Pethidine : codeine
Methadone : pethidine
Methadone : codeine
Morphine : codeine
Average
1-8
3-4
1-7
5-8
70
3-7
* n = number of comparative results.
Mice s.c.
Minimum
1-1
1-0
10
1-8
2-7
1-3
Maximum
3-8
5-7
2-1
100
130
6-8
The data listed in Tables II and III show:
17
14
5
12
8
8
Average
1-9
4-5
21
7-8
16 7-6
Rats s.c.
Minimum
1-2
2-4
11
4-5
7-2
5-6
Maximum
2-8
81
3-5
11-0
280
9-9
(a) That the results obtained in mice and in rats are quite similar.
(b) That the variations of the results obtained in methods characterized
by similar noxious stimuli, are as large as the variation of the combined
results.
(c) That there is no detectable correlation between "equiactive" dose
level and potency ratio.
(d) That the potency ratios and "equiactive" dose levels determined
after i.p. injection are not significantly different from those obtained after
s.c. injection.
(e) That the results obtained after oral or i.v. administration are quite
different from the s.c. and i.p. results. The agreement among different
authors is very poor.
(f) That too few experiments with other species have been carried out to
allow for useful discussion.
(g) That factors, other than those listed in Table II, must play an important
role in determining the outcome of the experiments.
10
6
3
5
4
4