Novel histaprodifen analogues as potent histamine H1-receptor agonists in the pithed and in the anaesthetized rat

We have shown previously that histaprodifen and its N α-substituted analogues methylhistaprodifen and dimethylhistaprodifen are highly potent H1-receptor agonists in vivo. The aim of the present study was to examine the influence of four newly synthesized histaprodifen analogues, 3-fluoro-methylhistaprodifen (1), N α-imidazolylethylhistaprodifen (2), bis-histaprodifen (3) and N α-methyl-bis-histaprodifen (4), on the cardiovascular system in the pithed and in the anaesthetized rat.