About This Calculator

The Bortezomib (Velcade) Dose Calculator is a clinical tool designed for healthcare professionals to accurately determine patient-specific dosing. It calculates Body Surface Area (BSA) using the DuBois formula and then computes the appropriate Bortezomib dose based on the prescribed mg/m² value. The calculator automatically incorporates dose adjustments based on key clinical factors, including hepatic impairment, peripheral neuropathy grade, and thrombocytopenia, as outlined in official prescribing information.

Outputs Explained

Upon calculation, the tool provides the following critical information for safe administration:

• Body Surface Area (BSA): The patient’s BSA in square meters (m²), calculated from their height and weight.
• Adjusted Prescribed Dose: The effective dose in mg/m² after applying any necessary reductions for hepatic impairment or neuropathy.
• Final Calculated Dose: The total dose in milligrams (mg) to be administered for the specific treatment session.
• Volume for Administration: The final volume in milliliters (mL) required for the injection, based on the selected reconstitution concentration (1 mg/mL or 2.5 mg/mL).
• Critical Warnings: A prominent alert advises withholding the dose if the patient’s platelet count is below 30 x10⁹/L.

How to Use

To use the calculator, follow these steps:

1. Enter the patient’s height and weight, selecting the correct units (cm/in and kg/lbs).
2. Verify the prescribed dose, which defaults to the standard 1.3 mg/m² but can be edited.
3. Select the patient’s level of hepatic impairment based on their latest bilirubin results relative to the Upper Limit of Normal (ULN).
4. Choose the appropriate peripheral neuropathy status if the patient has Grade 2 neuropathy with pain or Grade 3 or higher.
5. Enter the patient’s most recent platelet count to screen for severe thrombocytopenia. This field can be left blank if not relevant.
6. Select the final concentration of the reconstituted drug solution.
7. Click “Calculate Dose” to view the results.

Dosing Overview

Bortezomib is typically dosed at 1.3 mg/m² administered intravenously or subcutaneously. The dosing schedule varies by indication and treatment phase (induction, consolidation, maintenance). This tool applies dose modifications as recommended in the drug’s label:

• Hepatic Impairment: The dose is reduced to 0.8 mg/m² for moderate impairment (Bilirubin > 1.5–3x ULN) and 0.5 mg/m² for severe impairment (Bilirubin > 3x ULN).
• Peripheral Neuropathy (PN): For patients with Grade 2 PN with pain or Grade ≥ 3 PN, the dose is reduced to 0.7 mg/m².
• Thrombocytopenia: Dosing should be withheld if the platelet count is less than 30,000/mm³ (30 x10⁹/L). The dose can be reduced upon recovery, according to prescribing guidelines.
• Multiple Adjustments: If a patient meets criteria for multiple dose reductions, the tool will apply the lowest, most conservative dose.

Switching Between Formulations

Bortezomib can be administered via intravenous (IV) or subcutaneous (SC) injection. When switching from IV to SC administration, the starting dose is typically the same if the last IV dose was well-tolerated. However, the reconstitution concentrations differ. Always consult the official prescribing information for detailed instructions on reconstitution and administration for each route.

Missed Dose Protocol

If a dose of Bortezomib is missed, the management depends on the time elapsed. The prescribing physician should be consulted immediately for guidance. Patients should be advised not to administer a double dose to make up for the missed one. The treatment schedule may need to be adjusted by the clinical team.

Safety Alerts

This calculator is intended as a support tool and does not replace clinical judgment. All calculations must be independently verified.

• Hematologic Toxicity: Bortezomib frequently causes transient thrombocytopenia, neutropenia, and anemia. Complete blood counts should be monitored frequently throughout treatment.
• Peripheral Neuropathy: Bortezomib can cause a painful peripheral neuropathy that is predominantly sensory. Patients should be monitored for symptoms, and dose modification or discontinuation may be necessary.
• Hypotension: Postural hypotension can occur. Caution is advised when treating patients with a history of syncope or those receiving medications known to be associated with hypotension.

Frequently Asked Questions

What is the standard starting dose for Bortezomib (Velcade)?

The recommended starting dose for most indications is 1.3 mg/m².

How does the calculator determine Body Surface Area (BSA)?

It uses the DuBois and DuBois formula: BSA (m²) = √((Height(cm) × Weight(kg)) / 3600).

What happens if a patient has both severe hepatic impairment and neuropathy?

The calculator identifies the required dose for each condition (0.5 mg/m² for severe hepatic impairment, 0.7 mg/m² for neuropathy) and applies the lowest dose, which would be 0.5 mg/m².

Why is the platelet count a critical input?

According to prescribing guidelines, Bortezomib must be withheld if the platelet count falls below 30 x10⁹/L due to the high risk of bleeding. The calculator flags this as a critical warning.

Can I use this calculator for both subcutaneous and intravenous routes?

Yes, the dose calculation in mg is the same for both routes. However, the final volume will depend on the concentration used for reconstitution, which differs between IV and SC preparations.

What does “ULN” mean in the hepatic impairment section?

ULN stands for “Upper Limit of Normal,” which refers to the highest value of a lab test (in this case, bilirubin) considered normal for a healthy person.

Does this calculator account for renal impairment?

No. The calculator does not include an input for renal function because clinical studies have shown that Bortezomib pharmacokinetics are not influenced by the degree of renal impairment. Therefore, dose adjustments are generally not required for patients with renal insufficiency.

Who is this calculator intended for?

This tool is designed exclusively for use by qualified healthcare professionals, such as oncologists, pharmacists, and nurses, who are responsible for prescribing and administering chemotherapy.

References

• VELCADE® (bortezomib) for injection Prescribing Information. U.S. Food and Drug Administration. Accessed October 2023.
• Velcade (bortezomib) Summary of Product Characteristics (SmPC). European Medicines Agency. Accessed October 2023.
• VELCADE® (bortezomib) Official HCP Site. Takeda Pharmaceutical Company Limited. Accessed October 2023.
• Richardson PG, Sonneveld P, Schuster MW, et al. Bortezomib or high-dose dexamethasone for relapsed multiple myeloma. N Engl J Med. 2005;352(24):2487-2498. doi:10.1056/NEJMoa043445