Which of the following local anaesthetics is most likely to produce an allergic reaction:

D i.e. Benzocaine True anaphylaxis d/t anesthetic agent is rare; LA procaine may rarely cause it due to hapten carrier Anaphylactoid reactions are much more common. Hypnotic agents (thiopental & propofol) and muscle relaxants (Succinyl choline, curare & atracurium) are mostly responsible for it. Esters (local anesthetics) are more likely to induce IgE mediated immune response as they are derivatives of p-amino benzoic acid, a known allergen. Immunological response to amide L.A. is very rare. Methyl paraben a preservative agent is responsible for its most of rare allergic response. Till this time you must be remembering my formula of 2'i for amides. Only agent which is ester in these four options is benzocaine, so this is the answer