Table 1.

Pharmacokinetic parameters for morphine after i.v., s.c.b. or s.c.i. administration of morphine to healthy volunteers.

	i.v.	s.c.b.	s.c.i.
†Appearance t½ (h)	–	0.08 ± 0.03	1.53 ± 0.74 **
Elimination t½ (h)	2.2 ± 1.0	2.1 ± 0.4	2.2 ± 0.8
Apparent CL (ml min−1)	1584 ± 408	1385 ± 259	2125 ± 860
Apparent Vd (l)	276 ± 72	248 ± 74	406 ± 229
Cmax (nmol l−1)	283 ± 74	262 ± 49	46 ± 8***###
tmax (h)	0.08 (0.08-0.08)	0.25 (0.17-0.25)***	4.0 (3.5-5.0)***###
AUC(0,t) (nmol l−1 h)	269 ± 62	303 ± 55	198 ± 55 #
AUC(0,∞) (nmol l−1 h)	290 ± 67	323 ± 60	225 ± 49 #
Bioavailability (%)	100	113.6 ± 16.9	83.2 ± 34.6

Data standardized to 10 mg dose to 70 kg subject.

Results are mean±s.d. except t_max which is median (range).

i.v. = intravenous; s.c.b. = subcutaneous bolus; s.c.i. = subcutaneous infusion

^†Equivalent to absorption half-life for the parent drug

*P < 0.05 compared with i.v.

^**P < 0.01 compared with i.v.

^***P < 0.001 compared with i.v.

^# = P < 0.05 compared with s.c. b.

^## = P < 0.01 compared with s.c. b

^### = P < 0.001 compared with s.c.b.

N.B. Paired t-tests used throughout, except for appearance t_½ and t_max for M3G for which the Wilcoxon Signed-Ranks test was used as the data were not normally distributed.