[Isocimetidine and analogs. 23. H2-antihistaminics].

Isocimetidine (7), an isomer of cimetidine, as well as the analogous 4-pyrimidones 9a,b were prepared and tested for their H2- and H1-antagonistic activity. 9a,b possess similar pA2-values on the guinea-pig atrium, but smaller H2-selectivity than the corresponding cimetidine analogues, while 7 is less active than cimetidine.