Drug Allergy Desensitization and Drug Provocation Testing

Drug Allergy Desensitization and Drug Provocation Testing


 • Drug is administered in increasing doses over hours → mast cells/basophils eventually become unreactive to Ag activation. Once desensitized, pt can safely receive drug at usual intervals for a continuous period

 • Only induces TEMPORARY tolerance. After drug is stopped, desensitization ends over days-weeks

 • ONLY appropriate for Type I HSRs (NOT for Type II-IV)

     o Consult Allergy/Immunology for advice on dosage, admin and monitoring instructions, management of acute reaction

     o Perform in ICU except low-risk oral desensitization w/ hx of mild rxn: ASA, Bactrim, allopurinol, clopidogrel

Drug Provocation Testing (i.e., Test Dose): 

Used to assess pt’s reaction to a drug to which they may be allergic (i.e., to exclude drug allergy)

 • Absence of reaction to test dose → drug can be safely administered. Monitor for delayed Type 4 HSR.

 • Does NOT assess cross-reactivity of structurally-related drugs

 • Contraindication: h/o severe non-IgE mediated HSR (i.e., Type II-Type IV)

Test Dose Procedure:

 • Step 1: Test dose is 1/10 of treatment dose for IV meds; 1/4 of treatment dose for oral meds (Order name: “Test Dose”)

     o VS (by RN): before, 30mins, and 60mins after test dose

     o Orders: Epi 1:1000 IM (0.3 mg) PRN, Benadryl 50 mg IV/PO PRN

     o Hold: beta blockers (inhibit Epi) and ACE inhibitors (increased risk of allergic rxn) on day of procedure

     o Positive reaction: page the Allergy fellow (p13042) and file incident report

 • Step 2: If asymptomatic after 60 minutes, administer full treatment dose

     o VS (by RN): 30mins, 60mins after full dose

#Drug #Allergy #Desensitization #Provocation #Testing #management 
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