Arylsulfonamide derivatives

A compound of formula (I)

• or a pharmaceutically acceptable salt thereof,
• wherein
• L is a bond or —C≡C—;
• R1 is phenyl optionally substituted with 1 or 2 substituents independently selected from the group consisting of halogen, hydroxy, lower alkyl, lower alkoxy or haloalkyl;
• or pyridyl optionally substituted with halogen, lower alkyl, lower alkoxy or haloalkyl;
• or pyrazolyl optionally substituted with halogen, hydroxy, lower alkyl, lower alkoxy or haloalkyl;
• R2 is phenyl optionally substituted with 1 to 3 substituents selected from the group of halogen, hydroxy, lower alkyl, lower alkoxy, haloalkyl or alkoxyalkyl;
• or a heteroaryl group optionally substituted with halogen, hydroxy, lower alkyl, lower alkoxy, haloalkyl or alkoxyalkyl, wherein the heteroaryl group is selected from the group consisting of:
• and
• R3 and R4 are halogen, haloalkyl, lower alkyl or lower alkoxy.