Compounds of formula (I): wherein, Z is -N- or >CH; R 1 is -H or -C 1-4 alkyl; Ar 1 is 2-thiazoly, 2-pyridy, 3-pyridyl, 4-pyridyl, 2-pyrimidinyl, 4-primidinyl, 5-pyrimidinyl, or phenyl, each unsubstituted or substituted at a carbon ring member with one or two R a moieties; where each R a moiety is independently selected from the group consisting of -C 1-4 alkyl, -C 2-4 alkenyl, -OH, -OC 1-4 alkyl, halo -CF 3 , -OCF 3 , -SCF 3 , -SH, -S(O) 0-2 C 1-4 alkyl, -OSO 2 C 1-4 alkyl, -CO 2 C 1-4 alkyl, -CO 2 H, -COC 1-4 alkyl, -N(R b )R c , -SO 2 NR b R c , -NR b SO 2 R, -C(=O)NR b R c , -NO 2 , and -CN, wherein R b and R c are each independently -H or -C 1-4 alkyl; and Ar 2 is defined in the claims are useful as FAAH inhibitors. Such compounds may be used in pharmaceutical compositions and methods for the treatment of disease states, disorders, and conditions mediated by fatty acid amide hydrolase (FAAH) activity. Thus, the compounds may be administered to treat, e.g., anxiety, pain, inflammation, sleep disorders, eating disorders, or movement disorders (such as multiple sclerosis).