Table 1.

Pharmacokinetic parameter estimates of fentanyl for a three-compartment model derived from the fixed-dose IV infusion pre and post placebo or St. John’s wort (n = 8 in each group).

Parameter	Placebo		St. John’s wort
	pre	post	pre	post
V1 (L)	12.4 ± 4.4	12.4 ± 4.0	14.0 ± 4.5	14.9 ± 5.4
V2 (L)	16.9 ± 3.6	23.7 ± 12.4	28.2 ± 24.8	25.6 ± 15.3
V3 (L)	186 ± 30	153 ± 55	136 ± 47	151 ± 44
Vss (L)	215 ± 28	189 ± 45	178 ± 46	191 ± 50
CL10 (L/min)	0.96 ± 0.28	1.12 ± 0.27	1.13 ± 0.29	1.23 ± 0.26
CL12 (L/min)	1.40 ± 0.96	1.19 ± 0.31	1.27 ± 0.60	1.16± 0.55
CL13 (L/min)	1.48 ± 0.47	1.16 ± 0.51	1.31 ± 0.45	1.35 ± 0.31
k10 (min−1)	0.083 ± 0.032	0.101 ± 0.051	0.087 ± 0.028	0.092 ± 0.042
k12 (min−1)	0.144 ± 0.134	0.103 ± 0.039	0.101 ± 0.059	0.086 ± 0.048
k21 (min−1)	0.085 ± 0.048	0.057 ± 0.019	0.063 ± 0.030	0.058 ± 0.030
k13 (min−1)	0.138 ± 0.073	0.104 ± 0.064	0.106 ± 0.050	0.099 ± 0.039
k31 (min−1)	0.0080 ± 0.0023	0.0078 ± 0.0021	0.0098 ± 0.0032	0.0092 ± 0.0017
T½,α (min)	2.3 ± 1.3	2.3 ± 0.9	2.5 ± 1.1	2.5 ± 0.7
T½,β (min)	16.5 ± 6.9	21.2 ± 8.6	24.3 ± 20	21.5 ± 9.5
T½,γ (min)	258 ± 72	212 ± 65	181 ± 52	178 ± 32
MRT (min)	250 ± 103	183 ± 70	165 ± 52	158 ± 37

Generalized estimating equation analysis did not reveal a statistically significant treatment-by-day interaction for any of the parameter estimates.