A compound of formula I: or a pharmaceutically acceptable salt thereof, wherein: Ar 1 is a 5- to 10-membered mono- or bicyclic heteroaryl ring that contains 1-3 heteroatoms selected from the group consisting of N, O and S, wherein the 5- to 10-membered ring system is optionally substituted with 1-3 substituents independently selected from alkyl, halogen, -OH, -CN, nitro, alkoxy, -CF 3, -O-CF 3, -S(CH 3), -O-alkyl, -S-alkyl, -S -alkyl, -S(O 2)-alkyl, -S(O 2)-aryl,-CH 2 -aryl, heteroaryl, alkanoyl, -O-aryl, -O-CH 2 -aryl, -N(CH 3) 2, cycloalkyl, heterocycloalkyl, -C cycloalkyl, -C heterocycloalkyl, wherein the substituents may combine to form an optionally substituted 5-7 membered fused carbacyclic or heterocyclic ring, Ar 2 is a 5- to 10-membered mono- or bicyclic aryl ring, wherein the 5- to 10-membered ring system is optionally substituted with 1-3 substituents independently selected from alkyl, -F, -Cl, -Br, -OH, -CN, nitro, alkoxy, -CF 3, -OCF 3, -S(CH 3), -OCH 3, -S-alkyl, -S -alkyl, -S(O 2)-alkyl, -S(O 2)-aryl, -CH 2 -aryl, heteroaryl, alkanoyl, -O-aryl, -O-CH 2 -aryl, -N(CH 3) 2, cycloalkyl, heterocycloalkyl, -C cycloalkyl, -C -heterocycloalkyl, or substituted C 1-9 alkyl wherein the substituents may combine to form an optionally substituted 5-7 membered fused carbacyclic or heterocyclic ring; P is a heteroaryl ring selected from R 1, R 2 and R 3 are independently selected from -H, halogen, -OH, -CN, nitro, alkyl, alkoxy, -CF 3, -OCF 3, -CH 2 -aryl, phenyl, heteroaryl, alkanoyl, -O-aryl, -O-CH 2 -aryl, -N(CH 3) 2, -C -cycloalkyl, -C -heterocycloalkyl, -C O-alkyl, -C O-aryl, wherein the substituents may combine to form an optionally substituted 5-7 membered fused carbacyclic or heterocyclic ring. Ar 1 is a 5- to 10-membered mono- or bicyclic heteroaryl ring that contains 1-3 heteroatoms selected from the group consisting of N, O and S, wherein the 5- to 10-membered ring system is optionally substituted with 1-3 substituents independently selected from alkyl, halogen, -OH, -CN, nitro, alkoxy, -CF 3, -O-CF 3, -S(CH 3), -O-alkyl, -S-alkyl, -S -alkyl, -S(O 2)-alkyl, -S(O 2)-aryl,-CH 2 -aryl, heteroaryl, alkanoyl, -O-aryl, -O-CH 2 -aryl, -N(CH 3) 2, cycloalkyl, heterocycloalkyl, -C cycloalkyl, -C heterocycloalkyl, wherein the substituents may combine to form an optionally substituted 5-7 membered fused carbacyclic or heterocyclic ring, Ar 2 is a 5- to 10-membered mono- or bicyclic aryl ring, wherein the 5- to 10-membered ring system is optionally substituted with 1-3 substituents independently selected from alkyl, -F, -Cl, -Br, -OH, -CN, nitro, alkoxy, -CF 3, -OCF 3, -S(CH 3), -OCH 3, -S-alkyl, -S -alkyl, -S(O 2)-alkyl, -S(O 2)-aryl, -CH 2 -aryl, heteroaryl, alkanoyl, -O-aryl, -O-CH 2 -aryl, -N(CH 3) 2, cycloalkyl, heterocycloalkyl, -C cycloalkyl, -C -heterocycloalkyl, or substituted C 1-9 alkyl wherein the substituents may combine to form an optionally substituted 5-7 membered fused carbacyclic or heterocyclic ring; P is a heteroaryl ring selected from R 1, R 2 and R 3 are independently selected from -H, halogen, -OH, -CN, nitro, alkyl, alkoxy, -CF 3, -OCF 3, -CH 2 -aryl, phenyl, heteroaryl, alkanoyl, -O-aryl, -O-CH 2 -aryl, -N(CH 3) 2, -C -cycloalkyl, -C -heterocycloalkyl, -C O-alkyl, -C O-aryl, wherein the substituents may combine to form an optionally substituted 5-7 membered fused carbacyclic or heterocyclic ring.