Abstract Analogues of the potent histamine H 2 agonist arpromidine, characterized by non- heterocyclic groups (phenyl, cyclohexyl, alkyl) instead of the pheniramine-like portion, were prepared and tested for their H 2 agonistic and H 1 antagonistic activity in the isolated guinea pig right atrium and ileum, respectively. In the diphenylpropylguanidine series an increase in H 2 agonistic potency resulted from mono-or difluorination at one or both ...