Approach to Desensitization for Patients with History of Severe Allergic Reactions
For patients with a history of severe allergic reactions, desensitization should only be considered when the medication is essential and no equally effective alternatives exist, and should never be attempted in patients with previous life-threatening reactions. 1
Risk Assessment and Patient Selection
- Patients with previous very severe life-threatening reactions should not receive the implicated drug again, even with desensitization protocols 1
- Desensitization is appropriate for patients with previous mild to moderate reactions when the medication is essential for optimal therapy 2
- Consultation with an allergist should be considered before attempting desensitization, especially for platinum agents like carboplatin and cisplatin 1, 3
- Risk stratification should be based on the severity of previous reactions, with reactions graded from 1 (mild/cutaneous) to 4 (severe/anaphylaxis) 1
Preparation for Desensitization
- Ensure appropriate medical equipment and emergency medications are immediately available in the treatment area 1
- Standing orders should be written for immediate intervention in case a severe reaction occurs 1
- Desensitization should be performed in settings where staff are trained to manage allergic reactions, ideally in an intensive care unit for high-risk cases 1, 4
- Patient and family counseling about the possibility of reactions and recognition of symptoms is essential 1
Desensitization Protocols
- Desensitization involves administering increasing doses of the medication over a short period (hours to days) until the therapeutic dose is achieved 2, 5
- For severe reactions (grade 3-4), more cautious protocols are required:
- The temporary state of tolerance is maintained only with continuous administration; for intermittent therapies like chemotherapy, desensitization must be repeated for each cycle 2
Monitoring During Desensitization
- Continuous monitoring by experienced healthcare providers is essential during the entire desensitization procedure 5
- If reactions occur during desensitization, they are typically less severe than the initial reaction but require immediate intervention 4
- Success rates for desensitization protocols range from 80-90% when performed by experienced specialists 5, 6
Special Considerations for Different Medication Classes
- Platinum agents (carboplatin, cisplatin): Reactions typically occur after multiple exposures; skin testing between treatments may help identify patients at risk 3
- Taxanes (paclitaxel, docetaxel): Reactions often occur during the first few cycles; may be managed with slower infusion rates rather than formal desensitization for mild reactions 1
- Monoclonal antibodies: Risk stratification algorithms help determine appropriate management; grade 1 reactions may allow same-day rechallenge while grade 3-4 reactions require formal desensitization 1
Contraindications to Desensitization
- Previous severe life-threatening reactions 1
- Severe cutaneous adverse reactions including DRESS, SJS, TEN, or AGEP 1
- Patients with unstable cardiovascular or respiratory conditions 1
- Situations where alternative medications with similar efficacy are available 2
Long-term Management
- Desensitization induces only a temporary state of tolerance that requires continuous administration of the medication 2
- For intermittent therapies like chemotherapy, desensitization must be repeated for each treatment cycle 5
- Premedication alone without desensitization is insufficient to prevent recurrence of hypersensitivity reactions in sensitized patients 3
Desensitization should only be performed by allergists, trained nurses, and experienced pharmacists as it is a high-risk procedure that involves reintroducing allergenic medication to highly sensitized patients 7.