Patent ID: 7192947

Claim:
A compound of formula (I): wherein: R 1 and R 2 are both butyl; R 3 is hydrogen, hydroxy or halo; R 4 is C 1-4 alkyl optionally substituted by hydroxy, methoxy and methylS(O) a wherein a is 0–2 R 5 is hydroxy or HOC(O)CH(R 6 )NH—; R 6 is selected from hydrogen and C 1-3 alkyl optionally substituted by hydroxy, methoxy and methylS(O) a wherein a is 0–2; or a pharmaceutically acceptable salt, solvate or solvate of such a salt, or an in vivo hydrolysable ester formed on an available carboxy or hydroxy thereof, or an in vivo hydrolysable amide formed on an available carboxy thereof; with the proviso that when R 1 and R 2 are both butyl, R 5 is hydroxy and R 4 is methylthiomethyl, methylsulphinylmethyl, 2-methylthioethyl, hydroxymethyl, methoxymethyl; R 3 is not hydrogen; and with the proviso that when R 1 and R 2 are both butyl, R 5 is HOC(O)CH(R 6 )NH—, R 6 is hydroxymethyl and R 4 is hydroxymethyl; R 3 is not hydrogen.