TABLE 2

Antinociceptive potencies of 14-O-MeM6SU, M6SU, and morphine against acetic acid–induced nociception in the mouse writhing test after 20 minutes of subcutaneous and intracerebroventricular administration

At least four animals per dose group and three to four doses were used for each ED₅₀ determination.

Compound	ED₅₀ (95% Confidence Limits)		Subcutaneous/ Intracerebroventricular ED₅₀ Ratio^{^a}
Compound	Subcutaneous Administration	Intracerebroventricular Administration	Subcutaneous/ Intracerebroventricular ED₅₀ Ratio^{^a}
	nmol/kg	pmol/mouse
14-O-MeM6SU	87 (47–163)	1.7 (0.3–9.5)	51,177
M6SU	1993 (1282–3101)	9 (15–54)	221,444

↵^a Calculated as the subcutaneous administration (nmol/kg)/intracerebroventricular administration (pmol/mouse) ED₅₀ ratio.