Modulation of the immediate allergic wheal reaction in the skin by drugs inhibiting the effects of leukotriene C4 and prostaglandin D2

Objective: To study the effect of nordihydroguaiaretic acid (NDGA), zafirlukast and indomethacin on the size of the allergic prick-test wheal. Method: In the first part of the study, NDGA and indomethacin, as well as the mepyramine control (10 µg/ml and 100 µg/ml), were injected intracutaneously 10 min before prick-testing with the cow dander allergen in 51 sensitised atopic subjects. In the second part, five other subjects were prick-tested with several allergens followed by administration of 40 mg zafirlukast or 100 mg indomethacin and re-prick-testing 2 h or 4 h later. Results: The intracutaneous indomethacin at both concentrations enlarged the wheal by 27±50% and 29±51% (P<0.02, n=51), respectively. Likewise, the peroral indomethacin significantly increased the wheal area by 17±30% (P=0.035, n=5). Neither intracutaneous NDGA in 51 subjects nor peroral zafirlukast in 5 subjects had marked effects on the size of the prick-test wheal. As expected, mepyramine (10 µg/ml) decreased the wheal area by 33±32% (P<0.001, n=51), but 14 subjects did not show any decrease after administration of this H1-antihistamine. Conclusion: The prostaglandin synthesis inhibitor (indomethacin) augments the prick-test wheal, but the leukotriene synthesis inhibitor (NDGA) and leukotriene C4 antagonist (zafirlukast) have no marked effects on the size of the prick-test wheal.