About This Calculator

This Mylotarg (gemtuzumab ozogamicin) Dosing Calculator is designed to assist healthcare professionals by determining patient-specific dosing and preparation parameters. It automates calculations based on the patient’s body surface area (BSA) and the selected treatment regimen, adhering to guidelines in the official prescribing information.

Outputs Explained

After entering the required patient data, the calculator provides the following key outputs for a single dose administration:

• Body Surface Area (BSA): Calculated in m² using the Mosteller formula.
• Total Dose: The final dose of Mylotarg in mg, capped at a maximum of 4.5 mg as per prescribing guidelines.
• Vials Required: The number of 5 mg vials needed for the calculated dose. Due to the dose cap, this will always be one vial.
• Reconstitution Volume: The total volume of Sterile Water for Injection (SWFI) required to reconstitute the vial(s).
• Volume to Withdraw: The precise volume in mL of the reconstituted solution (1 mg/mL) to be withdrawn for dilution.

How to Use the Calculator

Follow these steps to ensure accurate calculation:

1. Enter Patient Height and Weight: Input the patient’s actual height and weight. You can toggle between metric (cm/kg) and imperial (in/lbs) units.
2. Select Treatment Regimen: Choose the appropriate indication and treatment phase (e.g., Induction, Consolidation) from the dropdown menu. This determines the dose rate (3.0 mg/m²).
3. Enter Baseline Total Bilirubin: Input the patient’s most recent total bilirubin level. This is a critical safety check, as Mylotarg is contraindicated in patients with levels > 2 mg/dL.
4. Calculate and Review: The calculator will automatically display the results. Always double-check the inputs and verify the calculated outputs against the official prescribing information and institutional protocols.

Dosing Overview

Mylotarg dosing is based on BSA for the approved regimens. The standard dose is 3 mg/m². A key safety feature incorporated into the dosing guidelines is a maximum dose cap.

Regardless of how high a patient’s BSA is, the total calculated dose is capped at a single 4.5 mg vial. This calculator automatically applies this cap if the BSA-based dose exceeds 4.5 mg, and will highlight this adjustment in the results.

Switching Treatment

Decisions regarding switching to, from, or between therapies containing gemtuzumab ozogamicin should be made by the treating physician based on a comprehensive clinical evaluation. This includes assessing treatment response, toxicity, and the patient’s overall condition. Refer to the full prescribing information for guidance on use in different lines of therapy.

Missed Dose

If a scheduled dose of Mylotarg is missed, consult the prescribing information and institutional guidelines for instructions on how to proceed. The decision to administer the dose, adjust the schedule, or omit the dose should be based on clinical judgment and the specific treatment protocol.

Safety Alerts

Frequently Asked Questions

Why is the dose capped at a maximum of 4.5 mg?

The 4.5 mg dose cap is a safety measure established in clinical trials and outlined in the FDA-approved prescribing information to mitigate the risk of severe toxicity, particularly hepatotoxicity (VOD/SOS).

What Body Surface Area (BSA) formula does the calculator use?

The calculator uses the Mosteller formula: BSA (m²) = √([Height(cm) x Weight(kg)] / 3600), which is a standard method for BSA calculation in oncology.

Why is baseline total bilirubin required for the calculation?

Baseline total bilirubin is a critical safety parameter. Mylotarg is contraindicated in patients with a total bilirubin greater than 2 mg/dL due to a significantly increased risk of severe and potentially fatal VOD/SOS. The calculator uses this input to provide a warning if the value exceeds this safety threshold.

What happens if I enter a bilirubin level over 2 mg/dL?

The tool will display an error message indicating that treatment is contraindicated, in line with the official safety warning.

How many vials of Mylotarg will I need for a single dose?

Due to the 4.5 mg maximum dose cap and the drug being supplied in 5 mg vials, you will only ever require one vial per dose for an adult patient.

Does this calculator account for dose reductions due to toxicity?

No. This tool calculates the initial recommended dose based on BSA and the selected regimen. Dose modifications or interruptions due to toxicities must be determined by the healthcare provider according to the full prescribing information.

Can I use this calculator for pediatric patients?

Mylotarg is approved for newly-diagnosed CD33-positive AML in pediatric patients (1 month and older). However, this calculator is designed for the adult dosing regimens shown. Always refer to the specific pediatric dosing section of the prescribing information.

What is the final concentration of the reconstituted drug?

After reconstituting a 5 mg vial with 5 mL of SWFI, the final concentration is 1 mg/mL.

References

• MYLOTARG® (gemtuzumab ozogamicin) for injection, for intravenous use. U.S. Prescribing Information. Pfizer Inc. Revised: 06/2020.
• Mylotarg for Healthcare Professionals. Pfizer Inc. Accessed October 2023.
• Mylotarg (gemtuzumab ozogamicin) – European Medicines Agency (EMA). Summary of Product Characteristics.
• Mosteller RD. Simplified calculation of body-surface area. N Engl J Med. 1987 Oct 22;317(17):1098. PMID: 3657876.