Allergic drug reactions are currently a major public health problem affecting
patient health and increasing healthcare costs. They are caused by interactions between a
drug and the human immune system and result in symptoms ranging from urticaria or angioedema
to those more serious such as anaphylaxis or anaphylactic shock. The most commonly
accepted mechanism for immunological activation is based on the hapten hypothesis. Drugs
are low molecular weight substances that cannot cause an immune response on their own.
However, they can act as haptens and form covalent adducts with proteins. The resulting
hapten-carrier (drug-protein) conjugate can induce the production of IgE antibodies or T
cells. An epitope, or antigenic determinant, is the part of the drug-protein antigen that is
specifically recognized by the immune system. This may involve not only the drug derivative
but also part of the carrier protein. Understanding the way in which drugs are metabolized
after protein conjugation is vital in order to make progresses in the diagnosis of clinical
allergy. In this review, recent advances in the identification of the chemical structures of antigenic determinants
involved in immediate allergic reactions to drugs are presented. We have focused on drugs that most commonly
elicit these reactions: betalactam and quinolone antibiotics and the non-steroidal anti-inflamatory drug pyrazolone.
This will be discussed from a chemical point of view, relating our understanding of drug structure, chemical
reactivity and immune recognition.
Keywords: Antigenic determinant, betalactams, dipyrone, drug allergy, IgE recognition, quinolones.
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