Tiotidine

Tiotidine (ICI 125211) is a potent and selective antagonist of histamine H2-receptor (pA2=7.3-7.8 for guinea-pig right atrium). Tiotidine has low affinity for both the H1 and the H3 receptors[1][2].

Research Areas >> Cardiovascular Disease

Signaling Pathways >> Immunology/Inflammation >> Histamine Receptor

Signaling Pathways >> GPCR/G Protein >> Histamine Receptor

H2 Receptor:7.3-7.8 (pA2)

H1 receptor:<4.5 (pA2)

H3 Receptor:4.8 (pA2)

Tiotidine competitively antagonizes the positive chronotropic action of histamine with an apparent dissociation constant of 30 μM (23-38 μM). Tiotidine abolishes H2-mediated increases in contractile force leaving H2-mediated negative inotropic responses unopposed. The actions of histamine at the A-V node, manifested by lengthening of the P-R interval and A-V block, are attenuated by 2.5 x 10(-7) M Tiotidine[2]. Tiotidine actually behaves as an inverse agonist in U-937 cells, diminishing basal cAMP levels[3].

[1]. Barth H, et al. Structural requirements of imidazole compounds to be inhibitors or activators of histaminemethyltransferase: investigation of histamine analogues and H2-receptor antagonists.

[2]. Trzeciakowski JP, et al. The cardiac pharmacology of tiotidine (LCL 125, 211): a new histamine H2-receptor antagonist. J Pharmacol Exp Ther. 1980 Sep;214(3):629-34.

[3]. Monczor F, et al. Tiotidine, a histamine H2 receptor inverse agonist that binds with high affinity to an inactive G-protein-coupled form of the receptor. Experimental support for the cubic ternary complex model. Mol Pharmacol. 2003 Aug;64(2):512-20.