Therapeutic agent for gait disturbance

A therapeutic agent for gait disturbance in a patient with ischemic disease, comprising a heterocyclic derivative represented by formula (1) below or a pharmaceutically acceptable salt thereof as an active component:

• wherein R1 and R2 are the same or different and each represents aryl optionally substituted with 1 to 3 substituents selected from the group consisting of a halogen atom, alkyl, haloalkyl, arylalkyl, alkoxy, alkylthio, alkoxyalkyl, alkylsulfonyl, hydroxy, amino, monoalkylamino, dialkylamino, carboxy, cyano, and nitro;
• R3 and R4 are the same or different and each represents a hydrogen atom or alkyl;
• R5 represents a hydrogen atom, alkyl, or a halogen atom;
• Y represents N or N->O;
• A represents NR6 and R6 represents a hydrogen atom, alkyl, alkenyl, or cycloalkyl;
• and
• D represents alkylene or alkenylene optionally substituted with hydroxy, or A and D are combined with each other to form a divalent group represented by formula (2) below:
• wherein r represents an integer of 0 to 2, q represents 2 or 3, and t represents an integer of 0 to 4;
• and
• E represents phenylene or a single bond, or D and E are combined with each other to form a divalent group represented by formula (3) below:
• wherein
• represents a single bond or a double bond,
• wherein u represents an integer of 0 to 2;
• v represents 0 or 1;
• G represents O, S, SO, or SO2;
• and
• Q represents carboxy, alkoxycarbonyl, tetrazolyl, carbamoyl, monoalkylcarbamoyl, dialkylcarbamoyl, or a group represented by formula (4) below:
• [Chem. 4]
• —CONH—SO2-R7 (4)
• wherein R7 represents amino, monoalkylamino, dialkylamino, or hydroxy;
• or any of groups 1) to 4) below:
• 1) alkyl,
• 2) aryl,
• 3) aryloxy, and
• 4) a heterocyclic group,
• optionally substituted with 1 to 3 substituents selected from the group consisting of a halogen atom, alkyl, haloalkyl, arylalkyl, alkoxy, alkylthio, alkoxyalkyl, alkylsulfonyl, hydroxy, amino, monoalkylamino, dialkylamino, carboxy, cyano, and nitro.