The present invention relates to a compound of formula I, or a pharmaceutically acceptable salt thereof. Formula (I), wherein R1 and R2 are each independently H or alkyl; Y is an alkyl group. CONR3R4, COOR5SO2NR16R17, NHSO2R18 or CN; X is an aryl or heteroaryl group, each of which may be optionally substituted with one or more substituents selected from (CH2)mZ where Z is halogen, OH, CN, alkyl, alkoxy, NO2, CF3, CONR6R7, CN, NR8R9, COOR10 or NHCOR11 and m is 0 to 3; R3 to R11 are each independently H, alkyl or aryl, wherein said alkyl and aryl groups are optionally substituted by one or more substituents selected from halogen, OH, CN, alkyl, alkoxy, NO2, CF3, CONR12R13, CN, NH2, COOR14, NHCOR15, and CN; R12 to R18 are each independently H or alkyl, more preferably H or Me; n is 1 to 6; wherein the compound is other than 3′,5′-dimethyl-4-(1,1-dimethylheptyl)-1,1′-biphenyl-2-ol. Further aspects of the invention related to the use of such compounds in the preparation of a medicament for the treatment of a muscular disorder, a gastrointestinal disorder, or for controlling spasticity or tremors.