I have a few good cites on that one. It's true that a "sulfa antibiotic" allergy does not equal a "sulfa cox2" allergy. The sulfa antibiotics have an arylamine group para to the sulfa moeity. Cox2's just have the sulfa tossed in there.
Author Affiliation:
Department of Medicine, University of Washington School of Medicine, Seattle, WA, USA.
Authors:
Slatore CG; Tilles SA
Number of References:
60
Abstract:
Sulfonamide antibiotics can result in a wide variety of hypersensitivity reactions. No validated diagnostic tests are available for sulfonamide reactions; therefore, clinicians must rely on the combination of a careful patient history, review of medical records, and a sound knowledge base regarding the common clinical manifestations of sulfonamide hypersensitivity reactions. Although HIV-infected individuals have a high risk for hypersensitivity reactions to sulfamethoxazole, readministering the drug can usually be performed safely by using a desensitization protocol. Sulfonamide-containing medications that are not antibiotics also have the capacity for causing hypersensitivity reactions. Whether the sulfa moiety confers a risk of cross-reaction is controversial. The preponderance of available evidence suggests that sulfonamide antibiotics probably do not cross-react with sulfonamide nonantibiotics
Sulfonamide hypersensitivity.
Slatore CG - Immunol Allergy Clin North Am - 01-AUG-2004; 24(3): 477-90, vii
From NIH/NLM MEDLINE
NLM Citation ID:
15242722 (PubMed)
Cross-reactivity
Many medications other than SMX have a sulfonamide moiety (see Fig. 2 ), including some of the most widely prescribed drugs, such as diuretics, sulfonylureas, and the recently introduced cyclooxygenase-2 (COX-2) inhibitor celecoxib. A fundamental difference between sulfonamide-containing antibiotics and nonantibiotics is the presence or absence of an arylamine group at the N4 position. This group is present only in the sulfa antibiotics, and, given the evidence implicating the arylamine group in the SMX hypersensitivity reaction, the absence of this group should reduce the likelihood of cross-reactivity with sulfonamide nonantibiotics. This question has become controversial, because some patients report histories of reactions to sulfa antibiotics and sulfa nonantibiotics. Table 4 [49] summarizes several case reports and small experimental studies addressing sulfonamide cross-reactivity. In addition, a recently published epidemiologic study [50] addressed the question of sulfonamide cross-reactivity by evaluating the medical records of more than 20,000 patients. The investigators found that, for patients who previously reacted adversely to a sulfonamide antibiotic, the odds ratio for a reaction to another sulfonamide was 6.6; however, this same group of sulfonamide-allergic patients was more likely to report an adverse reaction to penicillin (odds ratio of 7.8). Patients with a history of a penicillin reaction were more likely to react to sulfonamide nonantibiotics than were patients with prior sulfonamide antibiotic reactions. It was concluded that sulfonamide cross-reactivity is unlikely, but that certain individuals have a general predisposition to adverse reactions to multiple drugs.
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