ALLERGY TO CARBAMAZEPINE - PARALLEL IN-VIVO AND IN-VITRO DETECTION

Purpose: Five to 20% of patients discontinue antiepileptic drug (AED) therapy because of adverse reactions. Careful reintroduction, however, may be considered if true drug allergy can be ruled out. Definitive a ssessment of such immunologically mediated reactions requires demonstr ation of either specific antibodies or sensitized lymphocytes. Methods . We investigated whether skin patch tests (PTs) and in vitro lymphocy te proliferation assays (LPAs) were suitable for detection of allergy to carbamazepine (CBZ) and the possibly cross-reactive oxcarbazepine ( OCBZ). Data of 65 patients displaying a wide range of possibly allergi c side effects to CBZ were available for analysis. Data of CBZ users w ithout any side effects and healthy volunteers served as controls. Bot h PTs and LPAs were done with CBZ, OCBZ and three metabolites [CBZ-10, 11-epoxide (CBZ-E), 10-monohydroxy-CBZ (MHD), and 10,11-dihydroxy-CBZ (DIOL)]. Results: Positive PTs with CBZ were seen in 20% and with OCBZ in 14% of the patients. Positive LPA results with CBZ and OCBZ, respe ctively, were found in 40 and 19%. Both tests were positive in 14 and 7% of the patients. Cross-reactivity to OCBZ was seen in similar to 40 % of CBZ-reactive patients in both PTs and LPAs. Conclusion: These dat a illustrate the additional value of LPAs in the detection of CBZ alle rgy while showing that a major part of side effects to CBZ and OCBZ is not immunologically mediated, according to PTs and LPAs.