TABLE 2.

Positron Emission Tomography-Related Measures for Schizophrenia Patients and Healthy Comparison Subjects at Baseline and After Tiagabine Administration^a

	Schizophrenia Group (N=17)				Healthy Comparison Group (N=22)				Schizophrenia Group Versus Healthy Comparison Groupb
	Baseline		Posttiagabine		Baseline		Posttiagabine		Baseline	Posttiagabine
Measure	Mean	SD	Mean	SD	Mean	SD	Mean	SD	p	p
Tiagabine
Dose (mg/kg)			0.20	0.04			0.21	0.04		0.33
Plasma levelc (ng/mL)			244	157			223	152		0.67
[11C]Flumazenil
Injected dose (mCi)	20.7	1.2	20.8	1.6	19.6	2.9	19.9	2.4	0.19	0.21
Specific activity (Ci/mmol)	1,642	993	1,386	616	1,763	739	1,943	1,381	0.67	0.13
Injected mass (µg)	5.1	3.0	5.8	3.2	3.8	1.2	3.9	1.6	0.05	0.02
Free plasma fraction (%)	52.7	9.1	52.8	9.4	55.8	7.7	56.2	8.3	0.26	0.25
Clearanced (L/h)	60	16	64	19	50	18	62	23	0.08	0.74
Pons VT (or VND)e (mL/g)	1.0	0.2	1.0	0.2	1.0	0.2	1.0	0.2	0.90	0.68

^aExcept as otherwise noted, there were no significant differences between baseline and posttiagabine measures within the schizophrenia group or the healthy comparison group.

^bThe p values are based on unpaired two-tailed t tests.

^cThe tiagabine plasma level was calculated as the average of three measurements taken 30 minutes, 50 minutes, and 90 minutes after dosing.

^dSignificant difference between baseline and posttiagabine [¹¹C]flumazenil clearance in the healthy comparison group, p=0.04.

^eV_T=tissue distribution volume; V_ND=nondisplaceable tissue distribution volume.