Table 2. In vitro binding affinity.

Compound	Ki(nM) for TSPOa	Ki(nM) for CBRa
CB251	0.27 ± 0.09	>105
PK 11195	1.38 ± 0.42; 1.4 ± 0.4c	>105
PBR28	6.1 ± 6.4c	–
flunitrazepamb	–	5.11 ± 0.87

^aAffinity of compounds determined by displacement of [³H]PK 11195 and [³H]flunitrazepam from rat cerebrocortical samples. The data are expressed as the mean values of three separate experiments performed in duplicate, which differed by less than 10%.

^bFlunitrazepam, a selective ligand for CBR, was used for comparison.

^cAccording to Ref. 25.