Adamantane and memantine derivatives as peripheral NMDA receptor antagonists

Cationic compound of formula (I):

• wherein:
• R1 and R2 represent, independently of each other, a hydrogen atom or a (C1-C6)alkyl group;
• the group —(CH2)n-A is linked to the cycle in position (a) or (b);
• n is 0, 1, 2 or 3;
• A represents a —NR3R4 group or a —N+R3R4R5 group;
• R3, R4 and R5 represent, independently of each other, a hydrogen atom, a (C1-C10)alkyl group, a (C1-C10)alkoxy group, a (C1-C10)alkyl-C(═NH)(—OH) group, a (C3-C8)cycloalkane group, a 6- to 10-membered aryl group or a 5- to 12-membered heteroaryl group;
• said alkyl or alkoxy groups being optionally substituted with one or more —NR6R7 group, —N+R6R7R8 group, (C3-C8)cycloalkane group, 6- to 10-membered aryl group or 5- to 12-membered heteroaryl group;
• with R6, R7 and R8 represent, independently of each other, a hydrogen atom or a (C1-C6)alkyl;
• and
• the compound of formula (I) contains at least one positive charged nitrogen atom;
• provided that R1 and R2 are not both a hydrogen atom;
• and
• provided that when R1 and R2 are a methyl group, the group —(CH2)n-A is linked to the cycle in position (a), and n is 0, then A is not a group —N+H3.