Hypersensitivity Reactions

Allergic reactions to LAs may manifest as pruritus, erythema, rash, urticaria, angioedema, wheezing, asthma (coughing, difficulty breathing); and, rarely, anaphylaxis.14,19-25,28,29,52-55 Allergic reactions to ester-type LAs have been confirmed. Ester-type anesthetic agents are metabolized by plasma cholinesterases. One of the breakdown products, para-aminobenzoic acid (PABA) is a highly antigenic compound capable of sensitizing lymphocytes or eliciting the formation of IgE antibodies.

True allergy to amide-type LAs is rare.14,19-25,28,29,52-55 Patients allergic to ester-type LAs have not shown cross sensitivity to amide-type LAs and cross sensitivity among members of the amide-type LAs has not been reported. However, LAs formulated with a vasoconstrictor contain metabisulfite may precipitate an allergic reaction.21-25,56,57 The prevalence of sulfite allergy in the general population is unknown, but sulfite sensitivity is seen more frequently is patients with asthma.