Table 1.

The ED₅₀ of the antinociceptive effects of i.c.v. oxycodone and morphine

ED50 (nmol)	Vehicle	Tertiapin-Q	Shift ratio (T/V)
Oxycodone	1.29 (0.82–2.03)	9.15 (6.12–13.68)	7.09
Morphine	1.57 (1.05–2.36)	2.24 (1.59–3.18)	1.43

The ED₅₀ values were determined by linear regression using data from at least four doses in each opioid. Values in parentheses indicate the 95 % confidence range. The shift ratio (T/V) represents relative potency of the ED₅₀ values between vehicle group (V) and tertiapin-Q group (T). The ratio (O/M) represents relative efficacy of oxycodone over that of morphine.