About This Calculator

The Avastin (bevacizumab) Dosing Calculator is a clinical support tool designed to help healthcare professionals accurately determine patient-specific dosing, vial requirements, and infusion parameters based on the latest prescribing information. It streamlines the preparation process for bevacizumab administration across its various FDA-approved oncologic indications.

Calculator Outputs Explained

Upon entering the required patient and regimen data, the calculator provides the following key outputs:

• Total Dose Required (mg): The precise amount of bevacizumab in milligrams, calculated by multiplying the patient's weight in kilograms by the indication-specific dose (mg/kg).
• Total Drug Volume (mL): The volume of drug concentrate needed for the total dose, based on the standard Avastin concentration of 25 mg/mL.
• Vial Combination: A recommended combination of 100 mg and 400 mg vials to most efficiently achieve the total dose, aiming to minimize drug wastage.
• Total Infusion Volume (mL): The final volume for administration after the drug is diluted, typically in 100 mL of 0.9% Sodium Chloride.
• Calculated Infusion Rate (mL/hr): The rate at which the final solution should be infused intravenously, determined by dividing the total infusion volume by the selected infusion time.

How to Use the Calculator

Follow these steps to ensure an accurate calculation for your patient:

1. Select Indication & Regimen: Choose the appropriate cancer type and corresponding dosing regimen from the dropdown list. Some indications may have multiple approved dosing options.
2. Enter Patient Weight: Input the patient's current body weight. You can enter the value in either kilograms (kg) or pounds (lbs) using the unit selector.
3. Confirm Total Infusion Volume: The tool defaults to a standard final volume of 100 mL. Adjust this value only if your institutional protocol requires a different final volume.
4. Select Infusion Time: Choose the correct infusion duration based on the patient's treatment sequence: 90 minutes for the initial dose, 60 minutes for the second, and 30 minutes for all subsequent doses, if tolerated.
5. Calculate: Click the "Calculate Dose" button to generate the results. Always verify the outputs against the prescribing information and institutional protocols before preparing or administering the drug.

Dosing Overview

Bevacizumab is administered as an intravenous (IV) infusion. Dosing is weight-based and varies by indication. Common regimens included in this tool are:

• Metastatic Colorectal Cancer (mCRC): 5 mg/kg every 2 weeks or 10 mg/kg every 2 weeks.
• Non-Small Cell Lung Cancer (NSCLC): 15 mg/kg every 3 weeks.
• Glioblastoma: 10 mg/kg every 2 weeks.
• Metastatic Renal Cell Carcinoma (mRCC): 10 mg/kg every 2 weeks.
• Cervical, Ovarian, Fallopian Tube, or Peritoneal Cancer: 10 mg/kg every 2 weeks or 15 mg/kg every 3 weeks.
• Hepatocellular Carcinoma (HCC): 15 mg/kg every 3 weeks.

Doses are not typically reduced for adverse events. Therapy may need to be interrupted or permanently discontinued based on the severity of specific toxicities. Refer to the full prescribing information for detailed guidance on dose modifications.

Switching Between Infusion Times

The duration of bevacizumab infusion is tapered for patient tolerance. The first infusion should always be administered over 90 minutes. If the first dose is well-tolerated, the second infusion may be given over 60 minutes. If the 60-minute infusion is also well-tolerated, all subsequent infusions can be administered over 30 minutes. This calculator allows you to select the appropriate time to ensure the correct infusion rate is calculated for each administration.

Missed Dose Information

There is limited information on specific actions for a missed dose of bevacizumab. Clinical judgment should be used to determine if the patient's treatment schedule needs to be adjusted. The decision should be based on the patient's condition, the length of the delay, and the overall treatment plan. Consult with the oncology team to reschedule the administration as soon as appropriately possible.

Safety Alerts

Bevacizumab has Boxed Warnings for several serious and potentially fatal adverse reactions. Healthcare providers must be aware of these risks before and during treatment. Key warnings include:

• Gastrointestinal (GI) Perforation: The incidence of GI perforation, some fatal, is increased in patients receiving bevacizumab. Discontinue permanently if GI perforation occurs.
• Surgery and Wound Healing Complications: The incidence of wound healing complications, including serious and fatal ones, is increased. Discontinue at least 28 days prior to elective surgery. Do not initiate for at least 28 days following major surgery and until the surgical wound is fully healed.
• Hemorrhage: Severe or fatal hemorrhage, including hemoptysis, GI bleeding, and CNS hemorrhage, can occur. Do not administer to patients with recent serious hemorrhage or hemoptysis.

Frequently Asked Questions (FAQ)

References

1. AVASTIN® (bevacizumab) injection, for intravenous use. Prescribing Information. Genentech, Inc. Revised: 03/2024. Available at FDA.gov.
2. Genentech Oncology. Avastin (bevacizumab) for Healthcare Professionals. avastin-hcp.com.
3. U.S. Food and Drug Administration. Drugs@FDA: FDA-Approved Drugs. AVASTIN (bevacizumab) injection. Accessed October 2023.
4. National Cancer Institute. Bevacizumab. cancer.gov.