Pharmacological interactions between ranitidine, cimetidine, metiamide and tiotidine at histamine H2-receptor sites in guinea-pig atria.
Cumulative concentration-response curves to histamine or dimaprit were constructed on guinea-pig isolated right atria and agonist dose-ratios were determined following addition of ranitidine, cimetidine, metiamide or tiotidine alone or a combination of any two of these H2-receptor blocking drugs. The observed histamine or dimaprit dose-ratios for combinations of any two of the H2-antagonists tested were consistent with results predicted from the equation, DR1+2 = DR1 + DR2 - 1, for two antagonists competing for the same receptor sites. Therefore we conclude that all four H2-antagonists compete for the same histamine H2-receptor.
D000818:Animals; D002927:Cimetidine / Q000494:pharmacology / Q000031:analogs & derivatives; D017259:Dimaprit; D004347:Drug Interactions; D005663:Furans / Q000494:pharmacology; D006146:Guanidines / Q000494:pharmacology; D006168:Guinea Pigs; D006321:Heart / Q000187:drug effects*; D006339:Heart Rate / Q000187:drug effects; D006632:Histamine / Q000494:pharmacology; D066298:In Vitro Techniques; D008785:Metiamide / Q000494:pharmacology; D011899:Ranitidine; D011968:Receptors, Histamine / Q000187:drug effects*; D011970:Receptors, Histamine H2 / Q000187:drug effects*; D013844:Thiazoles / Q000494:pharmacology; D013890:Thiourea / Q000494:pharmacology
D005663:Furans; D006146:Guanidines; D011968:Receptors, Histamine; D011970:Receptors, Histamine H2; D013844:Thiazoles; D008785:Metiamide; D002927:Cimetidine; D006632:Histamine; D011899:Ranitidine; C023990:tiotidine; D013890:Thiourea; D017259:Dimaprit