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), zafirlu kast 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 t he mepyramine control (10 mug/ml and 100 mug/ml), were injected intracutane ously 10 min before prick-testing with the cow dander allergen in 51 sensit ised atopic subjects. In the second part, five other subjects were prick-te sted 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 th e wheal by 27 +/- 50% and 29 +/- 51% (P<0.02, n = 51), respectively. Likewi se, the peroral indomethacin significantly increased the wheal area by 17 /- 30% (P = 0.035, n = 5). Neither intracutaneous NDGA in 51 subjects nor p eroral zafirlukast in 5 subjects had marked effects on the size of the pric k-test wheal. As expected, mepyramine (10 <mu>g/ml) decreased the wheal are a by 33 +/- 32% (P < 0.001, n = 51), but 14 subjects did not show any decre ase after administration of this Hi-antihistamine. Conclusion: The prostaglandin synthesis inhibitor (indomethacin) augments t he prick-test wheal, but the leukotriene synthesis inhibitor (NDGA) and leu kotriene C4 antagonist (zafirlukast) have no marked effects on the size of the prick-test wheal.