About the Calculator

This guide provides supporting information for the Durvalumab (Imfinzi) Dosing Schedule Calculator. The tool is designed to assist healthcare professionals by calculating appropriate doses and generating projected infusion schedules based on indications and regimens approved in the U.S. Prescribing Information. It is intended for educational and informational purposes only and does not replace clinical judgment.

Outputs

Upon entering the required parameters, the calculator provides the following outputs:

How to Use

To generate a dosing schedule, follow these steps:

1. Select Indication: Choose the appropriate clinical indication from the dropdown menu (e.g., NSCLC, ES-SCLC). This determines the available dosing regimens.
2. Enter Treatment Start Date: Select the first planned day of infusion using the date picker. This date serves as the baseline for the entire schedule.
3. Specify Regimen & Weight (if applicable): If Stage III NSCLC is selected, choose between the fixed-dose (1500 mg Q4W) or weight-based (10 mg/kg Q2W) regimen. If weight-based is chosen, enter the patient's weight and select the unit (kg or lbs).
4. Calculate: Click the "Calculate Schedule" button to generate the results.

Dosing Overview

The calculator uses the following approved dosing regimens:

• Stage III NSCLC:
  • Weight-based: 10 mg/kg intravenously every 2 weeks (Q2W).
  • Fixed-dose: 1500 mg intravenously every 4 weeks (Q4W).
• ES-SCLC or Advanced BTC: 1500 mg intravenously every 3 weeks (Q3W) for the first 4 cycles (induction phase), followed by 1500 mg every 4 weeks (Q4W) as maintenance therapy.
• uHCC: 1500 mg intravenously every 4 weeks (Q4W).

Switching Regimens

The calculator does not provide guidance for switching between weight-based and fixed-dose regimens for NSCLC. Such decisions require clinical judgment and should be made in accordance with institutional protocols and the full Prescribing Information. A new calculation should be run if a switch is clinically determined.

Missed Dose

This tool cannot provide guidance on managing a missed dose. Clinical practice guidelines and the official Prescribing Information for Imfinzi should be consulted to determine the appropriate course of action for scheduling the next infusion.

Safety Alerts

Durvalumab (Imfinzi) is associated with serious risks, including immune-mediated adverse reactions. This calculator does not account for dose interruptions or discontinuations due to toxicity. Always consult the most current full Prescribing Information for complete safety information, including contraindications, warnings, precautions, and adverse reactions, before administering Durvalumab.

Frequently Asked Questions (FAQ)

1. What concentration of Durvalumab is used for the volume calculation?

   The calculation is based on the standard concentration of Imfinzi, which is 50 mg/mL.

2. How long is the generated treatment schedule?

   The tool projects a dosing schedule for a period of 24 months from the selected start date.

3. Does the calculator account for dose modifications due to adverse reactions?

   No, the calculator only provides the standard dosing schedule. It does not provide recommendations for dose delays, reductions, or discontinuations.

4. What is the difference between the "Induction" and "Maintenance" phases for ES-SCLC and BTC?

   The induction phase consists of the first four cycles administered every 3 weeks (Q3W). The maintenance phase begins after the fourth cycle, with infusions administered every 4 weeks (Q4W).

5. Can I use this tool for indications not listed in the dropdown?

   No. The tool is specifically programmed for the FDA-approved indications and regimens of Durvalumab listed.

6. What happens if a patient's weight changes during NSCLC treatment?

   The calculator performs a one-time calculation based on the weight entered. If a patient's weight changes significantly, a new calculation should be performed to ensure dose accuracy for the weight-based regimen.

7. Why is patient weight not required for the uHCC indication?

   The approved dosing regimen for unresectable Hepatocellular Carcinoma (uHCC) is a fixed dose of 1500 mg every 4 weeks and is not dependent on patient weight.

8. Is this tool a substitute for the official Prescribing Information?

   Absolutely not. This tool is for informational support only. The official full Prescribing Information is the definitive source for all dosing, administration, and safety information.

References

1. IMFINZI® (durvalumab) injection, for intravenous use. Full Prescribing Information. AstraZeneca. Updated 2024.
2. ImfinziHCP.com – Official Healthcare Professional Website. AstraZeneca.
3. FDA. Drug Approval Package: IMFINZI (durvalumab). U.S. Food & Drug Administration.
4. Antonia SJ, Villegas A, Daniel D, et al. Durvalumab after Chemoradiotherapy in Stage III Non–Small-Cell Lung Cancer. N Engl J Med. 2017;377(20):1919-1929.