evaluate and compare the effects of first generation anti-histamine [chlorpheniramine maleate] and second generation anti-histamine [Cetirizine dihydrochloride] on isolated trachea of rabbit

ABSTRACT

Histamine is generally considered as the principal mediator of the acute inflammatory process and the allergic and anaphylactic reaction in both the upper and lower respiratory airways. Chlorpheniramine maleate is a stable, most potent, .first generation antihistamine. It is clinical efficacy in the treatment of IgE mediated histamine disorders is well established. Cetirizine dihydrochloride is a potent, non-sedative HI receptor antagonist, belongs to second generation antihistamines. It is highly effective and safe drug for treating seasonal and perennial allergic rhinitis amid urticaria. Also used in chronic idiopathic urticaria and atopic dermatitis. The purpose of study was to evaluate the antagonostic effects of chlorpheniramine maleate and cetirizine dihydrochloride on histamine induced contractions in isolated trachea of rabbit and to compare the effects of first generation anti-histamine [chlorpheniramine maleate] and second generation anti-histamin [cetirizine dihydrochloride] on isolated trachea of rabbit. In this study twenty-four experiments were performed on isolated trachea of rabbit, in the presence of selected standard concentration of histamine dihydrochloride antagonistic effects of various concentrations of chlorpheniramine male-ate [10e-18 to 10e-3 gm/ml] and cetirizine dihydrochloride from concentrations to 10-3 gml ml were recorded by Polygraph Model 7B in terms of rate and amplitude. Chlorphenimmine maleate showed non-significant antagonistic effect from concentrations 10e-18 to 10e-9 gm/ml in case of rate and 10e-18 to 10e-8 gm/ml in case of amplitude. Significant response showed from concentrations 10e-8 to 10e-3 gm/ml in care of rate [P<0.001] and 10e-7 to 10e-3, gm/ml in case of amplitude [P<0.001] while, cetirizine showed non-significant response front concentrations to, gm/ml in case of rate and 10e-18 to 10e-12 gm/ml in case of amplitude. Significant response observed from concentrations 10e-12 to 10e-3 gm/ml in case of rate [P<0.001] and 10e-11 to 10e-3 gm/ml in case of amplitude [P<0.001]. It was concluded that chlorpheniramine maleate antagonized thetukl tisatnmd mine induced contractions 80.65% at concentration la, gm/ml in case of amplitude 11.35% at concentration 10e-3 gm/ml in case of rate and cetirizine dihydrochloride 82.69% in case of amplitude and 12.33% in case of rate