Recommendations for prevention of allergic diseases aimed at the high-risk newborn who has not manifested atopic disease include (1) breastfeeding for the first 4 to 6 months or (2) using a hydrolyzed casein formula (e.g., Alimentum or Nutramigen) or partially hydrolyzed whey formula (e.g., Good Start) (if supplementing) for the first 4 to 6 months and delaying introduction of solid foods until 4 to 6 months of age. Other approaches, such as maternal avoidance diets during pregnancy and during lactation, as well as avoidance of allergenic foods for infants beyond 6 months of age, are unproven.
An adverse drug reaction is defined as an unwanted, negative consequence associated with the use of a drug or biologic agent. Drug reactions can be classified as immunologic or nonimmunologic reactions (Table 85-1). Nearly 75% to 80% of adverse drug reactions are caused by a predictable, nonimmunologic mechanism, and between 5% and 10% of all drug reactions are explained by an immune-mediated mechanism. The remaining drug reactions are caused by an unpredictable mechanism, which may or may not be immune-mediated. The Gell and Coombs classification can be used to describe some drug-induced allergic reactions (see Table 77-1). Many drug reactions cannot be classified because the exact immune mechanism has not been defined. Most drugs cannot elicit an immune response because of their small size; rather, the drug or a metabolite acts as a hapten and binds to larger molecules, such as tissue or serum proteins, a process called haptenation.The multivalent hapten-protein complex forms a new immunogenic epitope that elicits Tand B-lymphocyte responses.
Drug reactions to penicillins and cephalosporins are the most common allergic drug reactions encountered in the pediatric population. Approximately 6% to 10% of children are labeled as penicillin allergic. Risk factors for drug reactions include previous drug exposure, increasing age (>20 years of age), parenteral or topical administration, higher dose, intermittent
Type IV reaction (delayed, cell-mediated) Contact dermatitis from topical antihistamine
Drug-drug interactions Torsades de pointes arrhythmia from terfenadine with erythromycin
Idiosyncratic Hemolytic anemia in a patient with G6PD deficiency after primaquine therapy
Intolerance Tinnitus after a single, small dose of aspirin
Adapted from Riedl MA, Casillas AM: Adverse drug reactions: types and treatment options, Am Fam Physician 68(9):1781−1790, 2003.
G6PD, Glucose-6-phosphate dehydrogenase.
repeated exposure, and a genetic predisposition of slow drug metabolism. An atopic background does not predispose an individual to the development of drug reactions but may indicate a greater risk of serious reaction.
Allergic reactions can be classified as immediate (anaphylactic) reactions, which occur within 60 minutes of drug administration; accelerated reactions, which begin l to 72 hours after drug administration; and late reactions, which occur after 72 hours. The most common form of adverse drug reaction is cutaneous. Accelerated reactions are usually dermatologic or serum sickness reactions. Late reactions include desquamating dermatitis, Stevens-Johnson syndrome, toxic epidermal necrolysis, and serum sickness.
Skin testing protocols are standardized for penicillin and are well described for other agents, such as local anesthetics, muscle relaxants, vaccines, and insulin. Positive skin testing to such reagents confirms the presence of antigen-specific IgE and supports the diagnosis of a type I hypersensitivity reaction in the appropriate clinical setting.