[Quinazolinones. 18. Synthesis and H1/H2-antihistaminic action of omega-[2-aryl-2,3-dihydro-4(1H)-quinazolinone-1-yl]alkyl substituted ureas and cyanoguanidines].

A series of (2-aryl-2,3-dihydro-4(1H)-quinazolinon-1-yl)alkyl-substituted cyanoguanidines and ureas with histamine, cimetidine or roxatidine partial structure was prepared and tested for H1- and H2-antagonism at the isolated ileum and the isolated right atrium of the guinea-pig. All compounds investigated were only very weak H1-antagonists, whereas the 3-[3-(1-piperidinyl-methyl)phenoxy]propyl-cyanoguanidines and -ureas were more potent H2-antagonists than cimetidine, maximally achieving about ranitidine's potency.