Table 2.

Comparison of pharmacological and physicochemical properties of morphine, 14-O-methyloxymorphone (1), 14-methoxymetopon (13), and its 5-benzyl-substituted analogue 15.

	Agonist activitya	Antinociception	Motor coordinationd	Log P g
	[35S]GTPγS (EC50, nM; % stim)	ED50 (mg/kg)
Morphine	462; 85	2.63b 2.29c	10e	0.88
1	23.7; 108	0.017b 0.014c	0.06e	0.60
13	63.0; 110	0.028b 0.028c	0.1e	1.12
15	13.7; 85	0.053b 0.043c	0.2f	1.49

EC₅₀: effective concentration necessary to produce a 50% effect; ED₅₀: effective analgesic dose to produce a 50% effect; log P: partition coefficient.

^aDetermined in [³⁵S]GTPγS functional assays in rat brain membranes; Data as % stimulation relative to DAMGO [14].

^bDetermined in the hot-plate test in mice after s.c. administration [14].

^cDetermined in the tail-flick test in mice after s.c. administration [14].

^dDetermined in the rotarod test in mice after s.c. administration [14].

^eSignificant decrease [14].

^fNo significant effect [14].

^gThe experimental log P determined in octanol/water [14].