Table 2. Heteroaryl Urea SAR.

		IC50 (nM)a
entry	Ar	hFAAH	rFAAH
17	phenyl	6 ± 4	300 ± 90
22	4-pyridyl	15 ± 6.1	520 ± 80b
23	3-pyridyl	1.4 ± 0.41	33 ± 9
24	2-pyridyl	12 ± 2.5	470 ± 180
25	4-pyrimidyl	41 ± 17	1500 ± 620

^aThese are apparent IC₅₀ values with values obtained after a 60 min preincubation with the enzyme; n ≥ 3 ± standard error.

^bN = 2.