Table 3.

Mean (± s.d.) pharmacokinetic parameter estimates of chlorzoxazone (500 mg) after oral administration in 32 volunteers.

	HealthyMean ± s.d. (90% CI*)	Type IMean ± s.d. (90% CI)	Obese Type IIMean ± s.d.(90% CI)	Healthyvs. Type I	90% CI on the difference†Healthyvs. Type II	Type Ivs. Type II
n	10	14	8
AUC∞0 (mg· h l−1)	43.5 ± 16.9	32.8 ± 9.2	15.7 ± 11.3‡	1.50, 19.88	15.6, 39.99	9.45, 24.76
	(36.0-50.8)	(28.7-36.8)	(9.1-22.2)
CL/F (l h−1)	13.0 ± 4.5	16.7 ± 5.7	43.8 ± 21.4‡	−7.47, 0.02	−38.28, −10.89	−32.47, −9.24
	(11.0-15.0)	(14.2-19.2)	(31.4-56.2)
CL/F (l h−1 kg−1)	0.18 ± 0.06	0.23 ± 0.14	0.43 ± 0.26‡	−0.13, 0.02	−0.39, −0.11	−0.34, −0.06
	(0.15-0.20)	(0.17-0.29)	(0.28-0.58)
Fraction unbound (%)	3.9 ± 2.1	4.0 ± 1.3	3.2 ± 2.6	−2.28, 0.67	−2.21, 2.20	−0.87, 2.47
	(2.2-4.1)	(3.4-4.5)	(1.6-4.7)
Half-life (h)	1.1 ± 0.2	1.2 ± 0.4	1.4 ± 0.9	−0.38, 0.13	−0.79, 0.24	−0.64, 0.34
	(1.0-1.2)	(1.1-1.5)	(0.9-2.0)
Tmax (h)	2.1 ± 1.0	2.7 ± 1.0	2.3 ± 1.1	−1.26, 0.10	−1.05, 0.63	−0.39, 1.13
	(1.7-2.5)	(2.3-3.1)	(1.7-2.9)
Cmax (µg ml−1)	15.0 ± 3.7	12.2 ± 4.4	5.2 ± 2.2‡	−0.33, 5.81	7.21, 12.35	4.01, 10.07
	(13.4-16.6)	(10.2-14.1)	(3.9-6.5)
Vd/F (l kg−1)	0.28 ± 0.08	0.40 ± 0.16	0.70 ± 0.26‡	−0.21, 0.02	−0.57, −0.27	−0.45, −0.17
	(0.25-0.32)	(0.33-0.47)	(0.55-0.85)
Peak 6-OHCHZ/CHZ serum conc. ratio	0.029§	0.010 ± 0.007	0.028 ± 0.012¶	n.a.	n.a.	−0.03, −0.01
		(0.007-0.013)	(0.022-0.033)
Urinary recovery (% of dose)	69.7 ± 7.9	61.4 ± 12.0	64.8 ± 13.5	−0.83, 15.83	−4.44, 14.21	−13.98, 7.09
	(66.2-73.2)	(56.1-66.7)	(58.9-70.7)

^*CI, Confidence interval; 6-OHCHZ, 6-hydroxychlorzoxazone; CHZ, chlorzoxazone; conc., concentration; n.a., not applicable.

^†The 90% confidence intervals are based on t-test with equal variance.

^‡Values significantly different (P≤0.05) from healthy and Type I values.

^§Value for one volunteer only, 6-hydroxychlorzoxazone not detectable in 9/10 healthy individuals.

^¶Value significantly different from Type I value.