Title: My patient really has all these drug allergies?<br/>Author: Kathy Prybys<br/><a href='http://umem.org/profiles/faculty/121/'>[Click to email author]</a><hr/><p style="color: rgb(187, 165, 4); font-size: 20px; font-family: verdana, arial, helvetica, sans-serif;"> <span style="font-size:14px;"><span style="color: rgb(34, 34, 34);">Misclassification of adverse drug effects as allergy is commonly encountered in clinical practice and can lead to use of suboptimal alternate medications which are often less effective.</span></span></p> <ul> <li style="color: rgb(187, 165, 4); font-size: 20px; font-family: verdana, arial, helvetica, sans-serif;"> <span style="font-size:14px;"><span style="color: rgb(34, 34, 34);">Nomenclature surrounding drug safety needs to be clear and unambiguous to avoid confusion. </span></span></li> <li style="color: rgb(187, 165, 4); font-size: 20px; font-family: verdana, arial, helvetica, sans-serif;"> <span style="color:#000000;"><span style="font-size:14px;">Adverse Drug Effect (ADE) = All drug induced disease. Majority are predictable based on drug's known pharmacology. Include harm related to medication errors and drug/food interactions. </span></span></li> <li style="color: rgb(187, 165, 4); font-size: 20px; font-family: verdana, arial, helvetica, sans-serif;"> <span style="color:#000000;"><span style="font-size:14px;">Adverse Drug Reaction (ADR) = Noxious or unintended reaction to a drug that is administered at therapeutic doses during normal use. Divided into predictable (majority 75-80%), related to pharmacologic actions of the drug in otherwise normal individuals) and unpredictable reactions (related to individual’s immunological response). </span></span></li> <li style="color: rgb(187, 165, 4); font-size: 20px; font-family: verdana, arial, helvetica, sans-serif;"> <span style="color:#000000;"><span style="font-size:14px;">"Drug allergies" are relatively uncommon with cited incidence of 10%.</span></span> <font color="#000000" style="font-size: 14px;">I</font><span style="font-size: 14px; color: rgb(34, 34, 34);">mmunologically mediated reactions (type I to IV) to a pharmaceutical and/or formulation (excipient) in a sensitized person. They are dose independent and unrelated to pharmacological action of the drug. Most commonly, IgE-mediated type I (immediate) reactions caused by rapid release of vasoactive mediators from mast cells and peripheral basophils causing generalized reaction including urticaria, angioedema, stridor, wheezing, and cardiovascular collapse.</span></li> <li style="color: rgb(187, 165, 4); font-size: 20px; font-family: verdana, arial, helvetica, sans-serif;"> <span style="color:#000000;"><span style="font-size:14px;">The skin is the most frequently and notably affected by drug induced allergic reactions.</span></span></li> <li style="color: rgb(187, 165, 4); font-size: 20px; font-family: verdana, arial, helvetica, sans-serif;"> <span style="font-size:14px;"><span style="color:#000000;">Antibiotics, particuarly Beta-Lactams, are the most important cause of immediate hypersensitivity reactions. Approximately 10% of patients report a history of penicillin allergy, however after complete evaluation, up to 90% of these individuals are able to tolerate penicillin and are designated as having “penicillin allergy” unnecessarily.</span></span></li> <li style="color: rgb(187, 165, 4); font-size: 20px; font-family: verdana, arial, helvetica, sans-serif;"> <span style="color:#000000;"><span style="font-size:14px;"> Pseudoallergy can occur with opioids due to histamine release. Codeine and morphine are most commonly associated with pseudoallergy. Coadministration of an antihistamine or use of a semi or synthethic opioid (Fentanyl, hydromorphone) can prevent this reaction.</span></span></li> </ul> <p style="color: rgb(187, 165, 4); font-size: 20px; font-family: verdana, arial, helvetica, sans-serif;"> </p> <p style="color: rgb(187, 165, 4); font-size: 20px; font-family: verdana, arial, helvetica, sans-serif;"> </p> <p> </p> <h3 style="color:#bba504;font-size:12px;font-weight:bold;font-family:verdana,arial,helvetica,sans-serif;"> </h3>
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<fieldset><legend>References</legend>
<p> Understanding adverse drug reactions and drug allergies: principles, diagnosis and treatment aspects. Pourpak Z, et al. Recent Pat Inflamm Allergy Drug Discov. 2008 Jan;2(1):24-46.</p> <p> Drug Allergy: An Updated Practice Parameter. Joint Task Force. Annals of Allergy, Asthma, & Immunology. Vol 105 ctober , 2010.</p> <p> Antibiotic allergies in the medical record: effect on drug selection and assessment of validity. Lutomski,DM. Pharmacotherapy. 2008 Nov;28(11) 1348-53.</p> <p> </p> </fieldset>