Pharmacological activities of two new histamine analogs.

The pharmacological properties of 2-aminohistamine and 2-amino-5-methylhistamine were studied and compared with those of histamine, 5-methylhistamine and dimaprit. The introduction of an amino group in position 2 of the histamine imidazole ring caused a reduction of histamine potency, mostly with respect to H1 receptors. Such disactivation was much more evident in its corresponding 5-methyl derivative. The pharmacological activity related to the chemical structure will be discussed in the paper.