The present invention is a compound and pharmaceutical composition comprising a compound of formula (I):
wherein R1 is a 4-(lower) alkyl-imidazol-1-yl or a 4,5-di(lower) alkyl-imidazol-1-yl group, R2 is a hydrogen atom or a lower alkyl group, and R3 is a fluorenyl group. The compound of formula (I) includes pharmaceutically acceptable salts: The compound of formula (I) and salts thereof have 5-HT antagonism activity.