[Synthesis and pharmacologic action of substituted imidazolyl- and thiazolylmethylthioethylguanidine]

Starting with diphenyl N-benzoyl-carbonimidate impromidine analogues characterized by various substituted imidazole or thiazole groups instead of the 5-methylimidazole part have been synthesized and tested for H2-agonistic and H1-antagonistic activity as well. The most potent substances 6h,i are 20-30 times more active than histamine at the H2-receptors in the isolated spontaneously beating guinea-pig right atrium. In isolated perfused guinea-pig hearts 6h,i were found to predominantly stimulate heart rate, whereas the increase in LVdp/dtmax was about 40% of impromidine's maximal response.