Important questions in Allergy: 1 – drug allergy/hypersensitivity

Important questions in Allergy: 1 -drug allergy/hypersensitivity Magnitude of the problemDrugs can induce several different types of immunological reactions which represent, together with nonallergic drug hypersensitivity reactions (DHRs), 15% of adverse drug reactions.Nonallergic DHRs resemble an allergy, without any proven immunological process.DHRs are a major cause of postmarketing withdrawal.They are also a daily worry for clinicians and patients.Even though urticarial and maculopapular eruptions are the most frequent manifestations, there are many other clinical forms, some of which are life-threatening, require or prolong hospitalization and entail changes in the drug prescription (1).DHRs affect more than 7% of the general population and therefore represent an important public health problem (2).Both under-diagnosis [because of under-reporting (2, 3)] and over-diagnosis [because of the over-use of the term ÔallergyÕ (2, 4)] are potential problems.Misclassification based on the drug allergy history may have consequences on individual treatment choices and can lead to the use of more expensive and less effective drugs.Drug hypersensitivity reactions have a significant impact on clinical practice, drug development and public health.However, epidemiological studies or research to better understand them and attempts to develop diagnostic and predictive tests have been limited.This fact was already recognized years ago by our American colleagues, who, after loosing some promising drugs as a result of severe DHRs, established a task force with representatives from the key stakeholders (research clinicians, regulatory scientists and immuno-toxicologists from the pharmaceutical industry) to identify critical data gaps and opportunities and to make recommendations on how to overcome some of the barriers to drug hypersensitivity research and address research needs (5).The situation in Europe was better, as most research was performed here, and as the interested people met already in two drug hypersensitivity meetings, the first one held in Bern in 2004, the second in Liverpool in 2006 and the third is planned in Paris, April 2008, (see http://www.dhm3.org).These meetings bring together people from industry and research.However, the problem is huge and much more efforts are needed to make our drugs safer.