Structure-activity relationships and drug allergy.

Structure-activity relationships (SARs) refer to the relation between chemical structure and pharmacologic activity for a series of compounds. Since the pioneering work of Crum-Brown and Fraser in 1868, they have been increasingly used in the pharmaceutical, chemical and cosmetic industries, especially for drug and chemical design purposes. Structure-activity relationships may be based on various techniques, ranging from considerations of similarity or diversity of molecules to mathematical relationships linking chemical structures to measured activities, the latter being referred to as quantitative SAR or QSAR. This review aims at briefly reviewing the history of SARs and highlighting their interest in delayed and immediate drug allergy using selected examples from the literature. Studies of SAR are commonly conducted in the area of contact dermatitis, a delayed hypersensitivity reaction, to determine the allergenic potential of a given compound without animal testing. In immediate, immunoglobulin E-mediated drug hypersensitivity, this kind of approach remains rather confidential. It has been mainly applied to neuromuscular blocking drugs (muscle relaxants) and betalactam antibiotics (penicillins, cephalosporins). This review shows that SARs can prove useful to (i) predict the allergenic potential of a chemical or a drug, (ii) help identify putative antigenic determinants for each patient or small group of patients sharing the same cross-reactivity pattern, and (iii) predict the likelihood of adverse reactions to related molecules and select safe alternatives.

Anaphylactic shock associated with cefuroxime axetil: structure-activity relationships.

OBJECTIVE: To present a predictive model of allergenicity based on a structure-activity relationship analysis of beta-lactam antibiotics using appropriate skin testing procedures. CASE SUMMARY: A 39-year-old woman was diagnosed with anaphylactic shock a few minutes after taking a 500 mg tablet cefuroxime of axetil and was admitted to the emergency department with dizziness, facial angioedema, generalized skin rash, and inferior cardiac ischemia. Skin testing confirmed the involvement of cefuroxime as the cause of the anaphylactic reaction, and the reaction was defined as probable according to the Naranjo probability scale. We then performed skin testing to study cross-reactivity between different beta-lactam antibiotics. In addition to this initial assessment, a structure-activity relationship (SAR) analysis was done. It showed that the patient was sensitized to beta-lactam antibiotics presenting a methoxyimino group, but not to similar compounds lacking this chemical group (eg, amoxicillin or penicillin G or V). Challenge with amoxicillin under intensive medical monitoring was tolerated up to a cumulated dose of 1 g, administered intravenously over 2 hours. DISCUSSION: This study demonstrates that SAR analysis could be useful to predict potential adverse reactions to related antibiotics and to select alternative strategies when antibiotic administration is essential. CONCLUSIONS: An SAR-based approach could help physicians and pharmacists provide allergic patients with relevant advice and propose viable alternatives regarding drug therapy.