Desensitization (temporary induction of drug tolerance):

• Indicated when the patient has a history of IgE-mediated penicillin allergy and/or is skin test positive, and has a serious infection where alternatives to penicillin are not suitable, e.g. syphilis in pregnancy.
• Will not prevent non-IgE-mediated reactions.
• Desensitization should never be attempted in patients with a history of reactions involving major organs (e.g. interstitial nephritis, hepatitis, hemolytic anemia, serum sickness, or severe cutaneous reactions (e.g. SJS, TEN, exfoliative dermatitis, AGEP, DRESS).
• Once complete, treatment with penicillin must be started immediately and must not be interrupted.
• Usually lost within two days after cessation of penicillin therapy. If penicillin is needed again in the future, desensitization must be repeated, i.e. patient still has an IgE-mediated allergy.
• Desensitization Protocols:

• • Oral method of penicillin desensitization (see Wendell GD, et al. N Engl J Med 1985;312:1229-32).

  • Intravenous method of ceftazidime desensitization (see Castells M. Curr Opin Allergy Clin Immunol 2006;6:476-81).

  • Rapid intravenous cephalosporin desensitization (see Win PH, et al. J Allergy Clin Immunol 2005;116:225-8).

  • Intravenous method of meropenem desensitization (see Wilson DL, et al. Ann Pharmacother 2003;37:1424-8).

  • Rapid intravenous method of imipenem desensitization (see Gorman SK, et al. Ann Pharmacother 2003;37:513-6).