Table 1

Effects of opioids and DA uptake blockers/releasers in rhesus monkeys trained to discriminate i.v. heroin from saline

Compound	Maximum Heroin-Lever Responding	ED₅₀	Maximum Suppression of Response Rate
	%	mg/kg	% control
Heroin	100.0 ± 0	0.02 ± 0.01	86.0 ± 10.0 [0.1]^1-a
Metabolites
6 MAM	87.1 ± 12.5	0.09 ± 0.05	72.7 ± 13.7 [0.3]
Morphine	99.5 ± 0.3	0.6 ± 0.3	71.9 ± 16.1 [0.56]
M3G	99.5 ± 0.4	3.4 ± 1.7	87.2 ± 12.0 [10.0]
M6G	80.0 ± 20.0	5.5 ± 2.4	91.3 ± 8.8 [10.0]
Selective opioids
Fentanyl	100.0 ± 0	0.003 ± 0.003	77.4 ± 1.4 [0.018]
Methadone	100.0 ± 0	0.02 ± 0.01	90.6 ± 2.6 [1.0]
Spiradoline	33.2 ± 33.2	—^1-b	8.3 ± 5.1 [0.03]
SNC 80	18.6 ± 15.5	—^1-b	20.7 ± 1.5 [0.3]
DA uptake blockers/releasers
Methamphetamine	0 ± 0	—^1-b	71.0 ± 33.0 [0.3]
Cocaine	13.0 ± 1.0	—^1-b	5.2 ± 4.8 [1.0]
GBR 12909	0 ± 0	—^1-b	54.2 ± 11.5 [1.0]

Data are means ± S.E.M.

↵1-a Numbers in square brackets indicate dose (mg/kg) that induced maximum suppression of responding.
↵1-b Heroin-lever responses <50%.