ABSTRACT
Drug-induced skin rashes occur in 2-3% of hospitalized patients. Depending on the pharmacological properties of a drug, reactions can be rated as an A-reaction (expected reaction) or B-reaction (unexpected or bizarre reaction). A-reactions comprise toxicity, for example, overdosage, inevitable side effects at a dosage necessary to achieve the desired effect such as chemotherapeutic agents as well as drug interactions. B-reactions result from the specifi c properties of each active pharmaceutical ingredient (API) and individual risk factors of the patient. A major cause of B-reactions is allergic reactions, which requires a specifi c T-cell-dependent sensitization of the patient leading to T-cell-or antibodydependent allergic reactions. The skin is a preferred target organ for B-type reactions. Dangerous reactions include anaphylaxis and angioedema as well as bullous drug reactions, especially toxic epidermal necrolysis (TEN). Most often involved drugs are antibiotics⎯in particular β-lactam antibiotics, sulfonamides, and quinolones⎯anticonvulsa nts, contrast media, and cytotoxic agents such as cisplatin derivatives. Investigations about the function of basophiles and their activities as well as the function of T cells in delayed-type reactions improved our understanding of the pathophysiology and led to new diagnostic options including in vitro assays. Recently established animal models as well as investigations on the level of antigen-presenting cells may improve the ability to predict the immunogenicity of low-molecular-weight compounds.
