Table 1. Pharmacokinetic Parameters of Morphine in the Rat Maternal Blood, Placenta, Fetus, and Amniotic Fluid after Morphine Administration (10 and 30 mg/kg, i.v.)^a.

	10 mg/kg, i.v.				30 mg/kg, i.v.
parameter	maternal blood	placenta	fetus	amniotic fluid	maternal blood	placenta	fetus	amniotic fluid
AIC of two-compartment	195.6 ± 26.85				223.7 ± 31.72
Model	Two-compartment	Noncompartment			Two-compartment	Noncompartment
	CP = 5.29 e–0.03t + 0.34 e–0.01t				CP = 27.58 e–0.03t + 5.49 e–0.01t
AUC (min μg/mL)	239.4 ± 93.08	62.50 ± 32.99b	81.73 ± 17.78b	88.02 ± 43.88b	1231 ± 171.5c	341.2 ± 275.6bc	229.6 ± 103.8bc	260.1 ± 146.6b
Cmax (μg/mL)	5.63 ± 2.74	0.38 ± 0.25b	0.34 ± 0.24b	0.36 ± 0.12b	33.07 ± 12.91c	0.71 ± 0.99b	0.87 ± 0.90b	1.17 ± 0.81bc
t1/2, α (min)	25 ± 9	-	-	-	26 ± 13	-	-	-
t1/2, β (min)	505 ± 638	-	-	-	278 ± 311	-	-	-
Tmax(min)	-	93 ± 94	87 ± 50	40 ± 13		160 ± 85	177 ± 69c	97 ± 39c
t1/2(min)	-	115 ± 90	271 ± 299	213 ± 134	-	661 ± 1052	269 ± 274	168 ± 141
CL (mL/min/kg)	46.30 ± 14.65	191.7 ± 77.83b	127.5 ± 28.89	138.6 ± 64.54b	24.74 ± 3.22c	163.7 ± 129.9	156.1 ± 71.65	193.9 ± 184.8
MRT (min)	134 ± 112	224 ± 122	433 ± 443	334 ± 208	86 ± 64	1038 ± 1559	477 ± 410	292 ± 201
AUCtissue/AUCblood	-	0.26 ± 0.14	0.34 ± 0.07	0.37 ± 0.18	-	0.28 ± 0.22	0.19 ± 0.08c	0.21 ± 0.12

^aData are expressed as means ± SD (n = 6). AUC_tissue/AUC_blood represents the maternal blood-to-tissue transfer ratio.

^bp < 0.05 compared with maternal blood within group by ANOVA with posthoc Tukey HSD test.

^cp < 0.05 compared with the same site in the morphine (10 mg/kg, i.v.) group by Mann–Whitney U test.