Desensitization Protocol Calculator
Dose escalation schedule for drug or allergen desensitization.
About this calculator
Rapid drug desensitization is a supervised procedure used when a patient needs a medication they have a documented hypersensitivity to and no equally effective substitute exists. Rather than one full-strength dose, the drug is given as a series of small, progressively larger doses so the immune system is exposed gradually. This calculator models the standard 12-step, three-solution protocol described by Castells and colleagues at Brigham and Women's Hospital in a landmark 2008 case series of 413 desensitizations: three solutions are prepared at increasing concentration (1/100, 1/10, and full strength of the target dose), and within each solution the dose is doubled across four steps, so the last step of the third solution delivers the full target dose.
Published case series of this 12-step protocol -- run across hundreds of desensitizations, mostly for chemotherapy hypersensitivity -- report that most patients tolerate the full protocol with mild or no reaction; breakthrough reactions occur in a meaningful minority of procedures, and severe or anaphylactic reactions are uncommon but not eliminated, which is why desensitization is always performed in a monitored clinical setting with resuscitation equipment on hand. The starting dose and cumulative dose scale with the target dose and starting dilution entered here; the reaction-risk figures reported are reference rates drawn from published desensitization literature, not a computation from this patient's specific inputs, so they should be read as general context rather than an individualized risk estimate.
Medical Disclaimer
This calculator is for informational and educational purposes only. It is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider before making decisions about your health. Never disregard professional medical advice or delay seeking it because of results from this tool.
Inputs
Results
Starting dose (mg)
0.1
Figures current as of 2008. Source: Castells MC, Tennant NM, Sloane DE, et al. Hypersensitivity reactions to chemotherapy: outcomes and safety of rapid desensitization in 413 cases. J Allergy Clin Immunol. 2008;122(3):574-580.
How to Use This Calculator
- Enter Target dose (mg), Starting dilution factor, and Steps per dilution.
- Set Step interval (minutes).
- Review the Starting dose (mg) result.
- Use Total steps and Total duration (hours) to inform your decision.
How the result changes with Starting dilution factor
| Starting dilution factor | Starting dose (mg) |
|---|---|
| 500 | 0.2 |
| 750 | 0.13 |
| 1,500 | 0.07 |
| 2,500 | 0.04 |
What each input means
- Target dose (mg)
- Full therapeutic dose to be achieved (mg).
- Starting dilution factor
- Initial dilution (e.g. 1000 = start at 1/1000 of target dose).
- Steps per dilution
- Number of dose doublings within each dilution solution.
- Step interval (minutes)
- Time between dose escalation steps.
What each result means
- Starting dose (mg)
- Initial dose at the most dilute concentration.
- Total steps
- Number of dose escalation steps in the protocol.
- Total duration (hours)
- Estimated total protocol duration.
- Cumulative dose (mg)
- Total drug administered during the protocol.
- Mild reaction risk (%)
- Estimated risk of mild hypersensitivity reaction.
- Severe reaction risk (%)
- Estimated risk of severe/anaphylactic reaction.
How this is calculated
Worked example, using the default values
- Identify Input Parameters4 parametersTarget dose (mg) = 100, Starting dilution factor = 1000, Steps per dilution = 3, Step interval (minutes) = 15 = 4 input(s) provided
- Calculate Starting doseStarting dose0.1 = 0.1
- Calculate Total durationTotal duration3 = 3
Figures and sources
- Standard 12-step, 3-solution rapid drug desensitization protocol (2008) — Castells MC, Tennant NM, Sloane DE, et al. Hypersensitivity reactions to chemotherapy: outcomes and safety of rapid desensitization in 413 cases. J Allergy Clin Immunol. 2008;122(3):574-580.
Engine last updated . Checked against 2 independently-derived tests — how we verify calculators. Built by Paul Gunder, a software engineer, not a licensed financial, medical, or legal professional.
Frequently Asked Questions
Why is the drug given in gradually increasing doses instead of all at once?
Rapid desensitization temporarily induces a state of tolerance by exposing mast cells and basophils to progressively larger amounts of the drug, rather than triggering them all at once with a full dose. Each of the 12 steps roughly doubles the previous dose within its solution, ending at the full target dose on the last step, which allows the procedure to be stopped or slowed if a reaction develops at a lower, more manageable dose.
Does changing the number of steps per dilution change the total protocol duration?
No -- this calculator models the fixed standard 12-step, three-solution protocol, so the total duration is driven by the step interval alone (12 steps multiplied by the minutes between steps). Real-world protocols sometimes use more or fewer steps per solution depending on institutional practice and patient risk, but that variation is not reflected in this calculator's fixed 12-step schedule.
How much does the target dose affect the starting dose of the protocol?
Directly and proportionally -- the starting dose is the target dose divided by the starting dilution factor, so doubling the target dose while keeping the dilution factor fixed doubles the starting dose too. A higher starting dilution factor (a more dilute first solution) lowers the starting dose for the same target dose, giving a more cautious first exposure.
Are the mild and severe reaction risk percentages specific to my inputs?
No -- they are fixed reference figures drawn from published rapid-desensitization case series, not calculated from the target dose, dilution, or interval entered above. They give general context for how often breakthrough reactions occur during the standard 12-step protocol, but actual risk for a specific patient and drug should be assessed by the supervising allergist or immunologist, not read off this calculator.
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