[Synthesis and pharmacologic action of arylmethylethylguanidines].

Impromidine analogous guanidines have been prepared characterized by H2-unspecific arylmethyl groups instead of the 5-methylimidazole residue. The most potent substances proved to be about 20 times more active than histamine at the isolated spontaneously beating guinea-pig right atrium (H2-agonism), simultaneously showing moderate H1-antagonistic activity at the guinea-pig ileum. In isolated perfused guinea-pig hearts the thenylthioethylguanidine 9e was very potent in increasing LVdp/dtmax, achieving about 90% of impromidine's maximal response. In comparison with impromidine the increase in heart rate was lower and rhythm disturbances were substantially reduced.