The effect of ranitidine, alone and in combination with clemastine, on allergen-induced cutaneous wheal-and-flare reactions in human skin.
The effect of intradermal ranitidine (administered alone and in combination with clemastine) on allergen-mediated wheal-and-flare reactions has been evaluated in a double-blind study on 10 healthy atopic volunteers. Ranitidine alone, administered in doses over a 10(4)-fold concentration range, had no effect on the size either of allergen-induced wheal or flare reactions. Clemastine alone evoked a dose-related inhibition of both wheal and flare. Compared to the inhibition achieved by clemastine alone, the combination of ranitidine with clemastine produced a small but significant increase in inhibition of allergen-induced flare at ranitidine concentrations of 10(-5) mol/L (p less than 0.001) and 10(-6) mol/L (p less than 0.01), and of allergen-induced wheal at ranitidine concentration 10(-5) mol/L (p less than 0.01). Our results provide further evidence for the presence of cutaneous histamine H2 receptors and their participation in the formation of allergen-mediated skin reactions but indicate that the contribution of cutaneous histamine H2-receptor stimulation to the production of immediate wheal-and-flare reactions evoked by allergen is only modest.
D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000276:immunology*; D002648:Child; D002974:Clemastine / Q000008:administration & dosage* / Q000494:pharmacology; D004359:Drug Therapy, Combination; D006801:Humans; D006969:Hypersensitivity, Immediate / Q000276:immunology; D011759:Pyrrolidines / Q000008:administration & dosage*; D011899:Ranitidine / Q000008:administration & dosage* / Q000494:pharmacology; D012867:Skin / Q000276:immunology*; D012882:Skin Tests
D000485:Allergens; D011759:Pyrrolidines; D011899:Ranitidine; D002974:Clemastine