Histamine h3 receptor ligands

PCT No. PCT/GB97/00358 Sec. 371 Date Oct. 6, 1998 Sec. 102(e) Date Oct. 6, 1998 PCT Filed Feb. 10, 1997 PCT Pub. No. WO97/29092 PCT Pub. Date Aug. 14, 1997Compounds of formula (I) or (II) wherein R1 is C4 to C20 hydrocarbyl (in which one or more hydrogen atoms may be replaced by halogen, and up to three carbon atoms may be replaced by oxygen, nitrogen or sulphur atoms, provided that R1 does not contain an -O-O- group), R2 is H or C1 to C3 alkyl, m is from 1 to 15, n is from 2 to 6, each X group is independently (a), or one X group is -N(R4)-, -O- or -S- and the remaining X groups are independently (a), wherein R3 is H, C1 to C6 alkyl, -CO2R5, -CONR52, -CR52OR6 or -OR5 (in which R5 and R6 are H or C1 to C3 alkyl), and R4 is H or C1 to C6 alkyl, each Y group is independently -C(R3)R4-, or up to two Y groups are -N(R4)-, -O- or -S- and the remaining Y groups are independently -C(R3)R4-, wherein R3 is as defined above, one R4 group in the structure is imidazoyl or imidazoylalkyl and the remaining R4 groups are H or C1 to C6 alkyl, and Z is >C(R7)NR2- or >N-, wherein R7 is any of the groups recited above for R3, and pharmaceutically acceptable salts thereof are ligands at histamine H3 receptors.