CHICAGO - Ever think about a food allergy when a patient experiences an allergic reaction to a drug? Rather than being allergic to the drug, the child may be allergic to the food additives that it contains.
During the recent Annual Meeting of the American Academy of Pediatrics here, Veena R. Kumar, MD, provided an example of such an allergy.
"A 5-year-old female patient of ours was given amoxicillin, Tylenol with Codeine Elixir (acetaminophen and codeine, McNeil) and Tylenol Children's Elixir (acetaminophen, McNeil) for postoperative pain management," she said.
The patient exhibited some type of allergic reaction to all three of these medicines. She was subsequently found to have a specific food and drug allergy to red dye no. 40.
Classic adverse reactions to medicines include urticaria, lethargy, severe asthma, wheezing and anaphylaxis. Urticaria is the most common reaction, and it can be an early sign of anaphylaxis. Prevalence of food hypersensitivity is about 4% to 6% in the first year of life.
"Most children outgrow this hypersensitivity in the first few years, except hypersensitivity to peanuts and nuts, which tends to stick with you throughout your life," she explained.
"Food and drug additives can be classified by their function, including coloring, flavoring, nutrient-stabilizing agents and bulking agents. Some common food additives include antioxidants, extraction solvents, flavoring agents, sweeteners and bulking agents. Finding the specific, comprehensive ingredient lists for different foods and drugs is pretty difficult," she said.
Many drug labels do not contain comprehensive lists of ingredients. Additionally, package inserts do not contain them. The only way to find out all the ingredients in a drug is by contacting the manufacturer.
"We looked at amoxicillin and Augmentin (amoxicillin-clavulanate, GlaxoSmithKline), two very commonly prescribed drugs in the pediatric population. GlaxoSmithKline does not use red dye no. 40 or yellow dye no. 6, but the manufacturer does. Tylenol, manufactured by McNeil, uses two different kinds of coloring agents depending on the flavor of the suspension. Keflex (cephalexin, Lilly), another commonly prescribed medicine, is manufactured by several different manufacturers," she said.
In addition, certain manufacturers will use different flavoring agents depending on the concentration of the medicine. Ibuprofen contains different flavoring agents depending on the company and the flavor of the medicine, according to Kumar.
Establishing a diagnosis of a food hypersensitivity is a lot easier if there is an acute episode when an easy cause-and-effect relationship is established. However, when there is chronic urticaria, it is more difficult to evaluate because of the sporadic episodes that happen over time.
Evaluation of patients usually should be undertaken in those patients who have highly suspicious signs and symptoms or in those patients who have urticaria that resolves when they go on an additive-free diet.
"Before undertaking a trial, you should obtain the necessary equipment and personnel for possible resuscitation of a patient with anaphylaxis. Antihistamines should probably be stopped before undertaking the trial as should ß2 agonists. Oral corticosteroids are okay. The initial trial is usually just a single blind trial. If there is no objective finding, then the diagnosis can pretty much be excluded. If it is positive, then a double-blind study should be performed," she said.
For more information:
- Kumar VR. Postoperative management difficulties in patients with unusual drug allergies. H208 Section on otolaryngology/bronchoesophagology and SENTAC. Presented at the 2000 Annual Meeting of the American Academy of Pediatrics. Oct. 28-Nov. 1, 2000. Chicago.
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