Table 2.

Pharmacokinetic parameters calculated from the intrathecal CSF concentration of morphine, M6G and [³H]sucrose after i.c.v. injection in rats

	Morphine	M6G	[3H]sucrose
Kel (min−1)	0.00723±0.00118	0.0128±0.0013	0.0119±0.0020
t1/2 (min)	102.0±20.0	55.4±5.1	69.4±15.2
AUC0–∞ (% dose min μl−1)	0.356±0.060†	13.1±4.5**	8.16±0.50

Each value represents the mean±s.e.m. of three (morphine, M6G) or six ([³H]sucrose) rats. Pharmacokinetic parameters were calculated from the data shown in Figure 2. Symbols show a significant difference from the values for morphine (**P<0.01) and [³H]sucrose (†P<0.05).