Iodobolpyramine and other iodinated derivatives as ligands for detecting histamine H1 receptors

Abstract The synthesis is described of potential I-labelled H 1 -receptor ligands. Receptor affinity is assessed in vitro from inhibition of histamine-stimulated contraction of guinea pig ileum and/or through binding to guinea pig cerebellar membranes. Direct iodination of mepyramine and of hydroxy analogues of mepyramine and temelastine (SKF the compound is purified by TLC and authenticated by HPLC comparison with non-radiolabelled mono- and di-iodinated bolpyramine derivatives. Cyanobutyl-and acetamidopentyl-analogues of mepyramine are also tested as histamine antagonists and structure—activity relationships are described.