Metachromatic reaction and antihistaminic drugs

We studied the effect of antihistaminic substance on the dye-polysaccharide interaction, using a model in vitro system consisting of heparin-Na and the basic dye o-toluidine blue. The results are recorded on absorption curves in the visible range under standard and modified experimental conditions. We concluded that both histamine and antihistaminic drugs interact in vitro with mucopolysaccharide substances. The results are discussed on a pharmacological basis.