Prostaglandins in contact urticaria induced by benzoic acid.

To study the role played by prostaglandins (PGs) in contact urticaria, concentrations of 13,14-dihydro-15-keto-PGF2 alpha, 6-keto-PGF1 alpha, and thromboxane B2, the stable metabolites of PGF2 alpha, prostacycline and thromboxane A2 were measured by radio-immunoassay of the fluid taken from suction blisters in 11 patients. The blisters were raised on contact urticarial reactions induced by benzoic acid. The effect of peroral indomethacin on contact urticaria from benzoic acid was studied in a further 14 dermatological patients. The levels of these prostanoids in the blister fluid of urticarial skin did not differ from those derived from control blisters raised on apparently normal skin. Premedication with indomethacin, 50 mg t.i.d., completely prevented contact urticarial reactions to benzoic acid in all patients.