Drug-allergic patients desensitization

Penicillin desensitization is the most common drug desensitization protocol and is required for penicillin-allergic patients when penicillin is clearly the best treatment option, e.g., when syphilis is present in pregnancy. Protocols have been adapted to most antibiotics. Tables 51-5 and 51-6 describe procedures for oral and intravenous penicillin desensitization.25... 

Most attempts to achieve long-lasting desensitization to drugs in allergic patients by repeated and progressive administration of the drug have been unsuccessful,... 

Parenterally administered penicillin is recommended for all stages of syphilis. Alternative agents may be used in allergic individuals and include doxycycline, minocycline, tetracycline, or erythromycin base or stearate. Some patients may not respond favorably to alternative modalities. Therefore, in patients who must be administered penicillin (i.e., patients who are pregnant or have central nervous system [CNS] involvement) or are allergic, desensitization must be performed before the drug is initiated. 

Fever, skin rashes, and other allergic manifestations may result from hypersensitivity to streptomycin. This occurs most frequently with prolonged contact with the drug either in patients who receive a prolonged course of treatment (eg, for tuberculosis) or in medical personnel who handle the drug. Desensitization is occasionally successful. 

Procedure Beta-lactam desensitization should be done in an intensive care unit and any concomitant risk factors for anaphylaxis, such as use of beta-blockers should be corrected. Protocols based on incremental use of the drug orally or parenterally have been described (190,193). The oral route is preferable and is associated with a lower incidence of adverse events, but mild transient reactions are frequent (171,194,195). Pregnant women with limited antibiotic choices have been treated with immunotherapy (196). Repeated administration will maintain a state of anergy, which is often lost after withdrawal (197). At the conclusion of therapy, patients must be informed that after withdrawal, they may once again become allergic to penicillin, with a new reaction to the first subsequent application (197). 

Treatment of these problems is by substituting another insulin species which does not cross-react with the antibodies, by desensitization, or by local or systemic administration of glucocorticoids. If a severe allergic reaction occurs, the drug has to be discontinued and the patient treated with the usual agents (e.g. adrenaline, antihistamines or corticosteroids). Patients who have experienced severe systemic allergic symptoms should be skin-tested with another insulin preparation before its initiation. Desensitization procedures may permit resumption of insulin administration. 

Answer B. Indications for the use of penicillin G are currently limited for a number of reasons. The drug has a narrow spectrum, is susceptible to beta-lactamases, and may cause hypersensitivity, and alternative antibiotics are available. However, penicillin G remains the drug of choice in syphilis, usually given IM as benzathine penicillin G, but as the Na or K salt IV in neurosyphilis. What would you do for patients who are highly allergic to penicillins (Consider tetracyclines, or possibly desensitization.)... 

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