The drug of concern is deemed irreplaceable
The drug of concern is more effective than available alternatives
The drug of concern is much safer than available alternatives
Uncontrolled asthma or uncontrolled cardiac disease
Hemodynamic instability
Gravely ill patients in which effective alternatives are readily available
History of severe non-IgE mediated hypersensitivity reaction. For example:
Desensitization only temporarily induces drug tolerance; DO NOT remove the allergy label from the patient’s medical record. If the medication is not continued, tolerance will dissipate in as little as 24 hours, or approximately 4 half-lives of the medication
There is a potential that desensitization could induce an acute hypersensitivity reaction; carefully evaluate risks and benefits in patients with a history of severe anaphylaxis and/or anaphylactic shock
Beta-blockers may interfere with the treatment of anaphylaxis; if possible, hold beta-blockers prior to desensitization
Antihistamines and corticosteroids may mask early signs of a hypersensitivity reaction; if possible, hold prior to desensitization. DO NOT pre-treat with these agents to prevent reactions
It is essential that the patient be observed continually, with one-to-one nursing care, for signs of a hypersensitivity reaction
Because desensitization exposes patients to drugs that have the potential to induce an acute hypersensitivity reaction, it should only be performed in a setting where anaphylaxis can be managed, preferably with staff comfortable and/or experienced with the management of anaphylaxis
Patient factors, such as severity of past reactions and comorbidities, may assist in determining the best location for the desensitization procedure
Desensitization has been shown to be safe, and does not always require to be performed in an intensive care unit. Many centres safely perform desensitization in a general ward or on an outpatient basis.
Written informed consent is mandatory prior to starting the procedure, since we are knowingly administering a medication that could provoke a hypersensitivity reaction
Benefits of the procedure should outweigh the risks
The physician should be available for immediate consultation, if required, throughout the procedure
All patients should have IV access BEFORE starting the procedure and any equipment or medications required to manage anaphylaxis should be readily available
Have all of the following medications readily available throughout the entire procedure:
Many desensitization protocols are available for both oral and intravenous formulations of beta-lactams
The oral route may be easier, more cost-effective, and potentially safer than the intravenous route
Medications are typically started at diluted doses, usually 1/10,000th of the target dose, and, if no reaction, doses are doubled every 15-20 minutes until the target dose is achieved
If a more conservative approach is desired for patients with a history of severe anaphylactic reactions, a starting dose of 1/1,000,000th of the target dose could be considered
During the desensitization procedure, vital signs should be monitored closely and patients should be instructed to report symptoms of any potential hypersensitivity reaction
One-to-one nursing is MANDATORY during desensitization; may consider cardiac monitoring.
Monitor for signs of an immediate hypersensitivity reaction (e.g. anaphylaxis, urticaria, angioedema, hypotension, bronchospasm, stridor, pruritis)
At baseline, and then at every dosing increment, monitor and record the following vital signs: T°, HR, RR, BP, and SaO₂
Upon completion of the procedure, monitor the vital signs listed above q30min x 4, then q6h x 4
Click here to access the NB-ASC Desensitization Guidelines for more details; such as sample densitization orders and protocols.
Guideline content derived from: NB Provincial Health Authorities Anti-Infective Stewardship Committee. Antimicrobial Desensitization. 05-2019
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