Histamine receiving links h3.

A compound of the formula in which A is (CH2) m, where m is 1 to 3; B is (CH2) n, where n is 1 to 3; X is 0 to 2; R1 is hydrocarbyl (C1 to C10), in which up to two carbon atoms can be replaced by O, S or N, and up to two hydrogen atoms can be replaced by halogen; R2 is H or hydrocarbyl (C1 to C15), in which up to three carbon atoms can be replaced by O, S or N, and up to three hydrogen atoms can be replaced by halogen; R3 is not present when -Y-Z-R2 is attached to W, or is H or hydrocarbyl (C1 to C7) when -Y-Z-R2 is not bound to W; W is nitrogen; X is -CH2-, O- or NR4, where R4 'H or (C1 to C3) alkyl; And it replaces a hydrogen atom in any of A, B, W and X, and is alkylene (C2 to C10), in which a non-terminal carbon atom can be replaced by O; and Z is where R5, R6 and R7 are independently H or hydrocarbyl (C1 to C15), in which up to three carbon atoms can be replaced by O or N, and up to three hydrogen atoms can be replaced by halogen, and Q is H or methyl, or Q joins R5 or R7 to form a five-member ring or Q joins R2 to form a six-member ring, with the proviso that when Z is R7