New selective histamine H1 agonists. Synthesis and pharmacology

In this article the synthesis and histaminergic H1 activity of a series of substituted 2-phenylhistamines are described. It appeared that substitution of the phenyl ring of these compounds influences the H1 activity substantially. In general, substitution in para position causes a decrease in H1 activity. However, in the meta-substituted members both increases and decreases of H1 activity have been observed; thus the meta nitro and meta methoxy derivatives are four times as potent as the parent 2-phenylhistamine. As far as investigated, neither H1 nor H3 activity could be established.