Antitussives

摘要

An antitussive which comprises, as an active ingredient, a tricyclic compound represented by Formula (I) [wherein R¹ represents a hydrogen atom, substituted or unsubstituted lower alkyl or the like, X¹-X²-X³ represents CR⁵-CR⁶-CR⁷-CR⁸ (wherein R⁵, R⁶, R⁷ and R⁸ may be the same or different and each represents a hydrogen atom, substituted or unsubstituted lower alkyl or the like, Y represents -CH₂S- or the like, and R² represents a hydrogen atom, substituted or unsubstituted lower alkyl or the like] or a pharmaceutically acceptable salt thereof.