ADVERSE REACTIONS TO LOCAL-ANESTHETICS - ANALYSIS OF 197 CASES

Background: Adverse drug reactions to local anesthetics are frequently reported. However, little is known about the underlying mechanisms. T herefore we investigated 177 patients a history of 197 events after ap plication of these drugs. Methods: The diagnostic approach included pr ick and intracutaneous tests, provocative challenge tests with causati ve and unrelated local anesthetics, and in selected cases, radioimmuno assays to detect specific IgE. In addition, tests were performed with preservatives, including sodium metabisulfite and parahydroxybenzoic a cid ester. Results: Results of prick and intracutaneous tests with loc al anesthetics were all negative. Only three patients reacted after su bcutaneous challenge with tile causative drug (local anesthetics of th e amide type) Although one patient showed a delayed-type response to m epivacaine, two patients had immediate-type reactions to articaine and lidocaine. However,; in both cases no specific IgE could be detected. In five patients with positive skill test reactions to preservatives, challenge test results remained negative. Conclusions: Two immediate- type reactions were not IgE-mediated. In only one of 197 reported adve rse reactions were we able to prove delayed-type allergic response. Th erefore true allergic reactions caused by local anesthetics are extrem ely rare.