[Racemic guanidinothiazoles with H2-antihistaminic activity. 13 H2-antihistaminics].

In studies on H2-antihistaminics with cyclic guanidine structure, side-chain branched racemic guanidinothiazoles were prepared and tested for their H2-antihistaminic activity on the isolated guinea-pig atrium. A simple synthesis of alpha-branched guanidinothiazoles is described. Of the prepared substances the racemic 14a, b in particular show high H2-antagonistic activity.