Drug challenge and desensitization protocols

Readministration of incriminated medications may involve drug challenges and desensitization protocols that are classified as true immunologic desensitization or test-dosing protocols. In the case of penicillin-induced, IgE-mediated reactions, such as severe urticaria and angioedema, true desensitization involves very cautious readministration beginning with small doses of a β-lactam antibiotic. Subsequently, the antibiotic administration causes the disappearance of immediate cutaneous reactivity, representing neutralization of IgE antibodies. In contrast, most drug challenges are performed empirically, beginning with subanaphylactic or subreactive doses. These challenges require proper planning, patient consent, expectation of inducing an untoward reaction, and preparedness for treatment of the reaction.