Synthesis and assessment of formamidines as new histamine H2-receptor antagonists.

Four series of compounds whose substructure contains a formamidine functionalized as a novel group in the chemistry of histamine H2-receptors have been synthesized. Series design, synthesis and pharmacological data including inhibition of histamine-stimulated acid secretion, inhibition of acid secretion p.o. and pA2 are reported. N-[(E)-[[2-[[[2](Diaminomethylene)amino]-4-thiazolyl] methyl]thio]ethyl]amino]methylene]-4-bromo-benzenesulfonamide (ebrotidine, CAS 100981-43-9, FI-3542) was selected for further research.