Arylsulfonamide derivatives

A compound of formula (I)

• wherein
• L is a bond or —C≡C—;
• R1 is phenyl optionally substituted with 1 or 2 substituents independently selected from 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 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, selected from
• R3 and R4 are halogen, haloalkyl, lower alkyl or lower alkoxy;
• or a pharmaceutically acceptable salt thereof.