The present invention provides compounds of formula (I) including stereoisomers or a racemate or a mixture or a pharmaceutically acceptable salt thereof: wherein X is NH, or O; Q is 5-6 membered heteroaryl group, which may be substituted by one or more substituents independently selected from a group consisting of: C1-C4 alkyl, halogen, halo C1-C4 alkyl, C1-C4 alkoxy, CN; A is phenyl or a 5-6 heteroaryl group, which may be substituted by one or more substituents independently selected from a group consisting of: C1-C4 alkyl, halogen, halo C1-C4 alkyl, C1-C4 alkoxy, CN; B may assume different meanings from A and is phenyl or a 5-6 membered heteroaryl group, which may be substituted by one or more substituents independently selected from a group consisting of: C1-C4 alkyl, halogen, halo C1-C4 alkyl, C1-C4 alkoxy, CN; and processes for their preparation, pharmaceutical compositions containing them and their use as dual antagonists of the Orexin 1 and Orexin 2 receptors.