Benzimidazole derivatives as selective blockers of persistent sodium current

A method of blocking persistent sodium current without affecting transient current in a mammal comprising administering to said mammal in need thereof a therapeutically effective amount of the compound of Formula I

• or a pharmaceutically acceptable salt thereof;
• wherein:
• R is C1-6 alkyl, which is unsubstituted or substituted with a substituent selected from the group consisting of —N(C1-6 alkyl)2, C6-12 aryl, C6-12 aryloxy, heteroaryl, and —C(═O)—N(R6)—C6-12 aryl;
• each R1 and R2 are independently H or C1-6 alkyl;
• R3 and R4 together with the nitrogen atoms to which they are shown attached form a five- or six-membered heterocyclyl group selected from the group consisting of pyrrolidinyl, piperidinyl, piperazinyl, and morpholinyl, each of which is independently unsubstituted or substituted with a ring system substituent;
• R5 is selected from the group consisting of C1-6 alkyl, and C1-6 alkoxy, wherein said C1-6 alkyl and the “alkyl” portion of said C1-6 alkoxy are independently unsubstituted or substituted with a substituent selected from the group consisting of hydroxyl, —C(═O)OH, —C(═O)O—C1-6 alkyl, —C(═O)-heterocyclyl, and —N(C1-6 alkyl)2;
• R6 is H or C1-6 alkyl;
• m is 1 or 2;
• and
• n is 0 or 1.

A method of treating a disease or condition in a mammal, wherein said disease or condition is mediated by elevated persistent sodium current, comprising administering to said mammal in need thereof an effective amount of a compound of Formula I

• or a pharmaceutically acceptable salt thereof;
• wherein:
• R is C1-6 alkyl, which is unsubstituted or substituted with a substituent selected from the group consisting of —N(C1-6 alkyl)2, C6-12 aryl, C6-12 aryloxy, heteroaryl, and —C(═O)—N(R6)—C6-12 aryl;
• each R1 and R2 are independently H or C1-6 alkyl;
• R3 and R4 together with the nitrogen atoms to which they are shown attached form a five- or six-membered heterocyclyl group selected from the group consisting of pyrrolidinyl, piperidinyl, piperazinyl, and morpholinyl, each of which is independently unsubstituted or substituted with a ring system substituent;
• R5 is selected from the group consisting of C1-6 alkyl, and C1-6 alkoxy, wherein said C1-6 alkyl and the “alkyl” portion of said C1-6 alkoxy are independently unsubstituted or substituted with a substituent selected from the group consisting of hydroxyl, —C(═O)OH, —C(═O)O—C1-6 alkyl, —C(═O)-heterocyclyl, and —N(C1-6 alkyl)2;
• R6 is H or C1-6 alkyl;
• m is 1 or 2;
• and
• n is 0 or 1.