Delayed hypersensitivity due to epidural block with ropivacaine

Editor—True allergy to amide type local anaesthetic drugs is extremely rare, and, because of the serious implications for the patient (for example, dentistry without pain control), it is one that must be made with great care and by excluding all other possible causes. In testing their patient's sensitivity with a preservative free solution from an ampoule without a latex rubber stopper, Ban and Hattori were obviously aware of the need to avoid those two common confounders, and the case that they present seems definitive, but several aspects of their report concern me.¹

Firstly, their patient seems to have received a daily dose of epidural ropivacaine of 96-192 mg for a period of two weeks. This is considerably in excess of the approved maximum duration of continuous administration of this drug (72 hours), but this is not mentioned. Nor is there any discussion of the possible role of cumulative local anaesthetic toxicity in the generation of the hypersensitivity, or of the possibility that “plasticisers” from the containers might have played a part, given the very large volume of solution that the patient must have received in a two week period.

Secondly, no detail is given of the technical aspects of the “intradermal” test.

Thirdly, the authors say that ropivacaine may cause allergic reactions characterised by signs such as urticaria, angioneurotic oedema, but I know of no published reports of such features. Can they provide definitive references, please?