the h1-receptor antagonists ( + ) -chlorpheniramine and promethazine similarly had no effect on the ec50 value for histamine in guinea-pig ileum , while promethazine competitively antagonized the muscarinic receptor-mediated inositol phospholipid response in this tissue ( ka 3.6 x 10 ( 7 ) m-1 ) .
C2757048
h1-receptor antagonists
C0008281
chlorpheniramine