2 CASES OF SPECIFIC ADVERSE REACTIONS TO SYSTEMIC CORTICOSTEROIDS

Although true allergic reactions due to systemic corticosteroid therap y are not frequent, they should be kept in mind since allergic reactio ns to this kind of therapy are possible. We report two cases of specif ic adverse reactions resulting from systemic corticosteroid therapy wh ich were diagnosed by provocation tests. The corticosteroids involved in each case were paramethasone and betamethasone, and methyl-predniso lone in both of them. Additives and other corticosteroids were studied by skin tests and challenges, with negative results. The structures o f paramethasone and betamethasone are similar with a 16 carbon methyl group in both, and with a fluoride in the alpha position of the 6 carb on in paramethasone, and a fluoride in the beta position of the 9 carb on and a 6 carbon methyl group in betamethasone. Methyl-prednisolone d iffers from that of other corticosteroids in its 6 carbon methyl group . We report two cases of specific adverse reactions caused by corticos teroids. Positive challenge tests showed a possible immunologic hypers ensitivity mechanism in both cases. The patients' reactions demonstrat ed cross-reactivity between methyl-prednisolone and the corticosteroid s having a 16 carbon methyl group, and fluoride or methyl radicals on the 6 carbon.