| abstract |
A compound represented by formula (A) [wherein Q represents -CH- or a nitrogen atom; R 1a and R 1b independently represent a C 1-6 alkyl group or the like; R 1c represents a hydrogen atom or the like; R 2a , R 2b , R 2c and R 2d independently represent a hydrogen atom, a halogen atom or the like; R 3a , R 3b and R 3c independently represent a hydrogen atom, a halogen atom or the like; and R 3d represents a hydrogen atom or the like] or a pharmaceutically acceptable salt thereof, which has an antagonistic activity on an orexin receptor, and therefore can be used as a therapeutic agent for sleep disorders, such as insomnia, on which the antagonistic activity on an orexin receptor is effective. |