About This Guide

This section provides supplementary clinical context for the Vyvgart Hytrulo (efgartigimod alfa and hyaluronidase-qlhc) Dosing Calculator. It explains the tool's parameters, outputs, and the underlying dosing principles based on the official Prescribing Information. This information is intended to support, not replace, professional medical judgment.

Understanding the Calculator Outputs

The tool generates a dosing schedule for one treatment cycle. Key outputs include:

• Complete Dosing Schedule: Provides the specific dates for all four weekly doses within a single treatment cycle, starting from the selected date.
• Next Cycle Planning: Calculates and displays the earliest possible start date for the subsequent treatment cycle, which is 50 days after the start of the current cycle.
• Safety Check Notification: If a previous cycle start date is entered, the tool will issue a warning if the new cycle begins sooner than the recommended 50-day minimum interval.

How to Use the Calculator

To generate a dosing schedule, follow these steps:

1. Select Start Date of Treatment Cycle: In the first field, enter the date of the first planned dose for the new treatment cycle.
2. Optional - Enter Previous Cycle Start Date: In the second field, enter the start date of the patient's most recent treatment cycle. This helps verify that a sufficient amount of time has passed before initiating a new cycle.
3. Calculate: The tool will display the dates for the four weekly doses and provide guidance on the next cycle's timing.

Dosing Overview

Vyvgart Hytrulo is administered for the treatment of generalized myasthenia gravis (gMG) in adult patients who are anti-AChR antibody positive. The recommended dosage regimen is as follows:

• Recommended Dose: 1,008 mg efgartigimod alfa and 11,200 units hyaluronidase, administered as a subcutaneous injection over 30-90 seconds.
• Treatment Cycle: A cycle consists of one injection per week for four consecutive weeks.
• Subsequent Cycles: The frequency of subsequent treatment cycles should be determined by clinical evaluation and individual patient response. The safety of initiating subsequent cycles sooner than 50 days from the start of the previous cycle has not been established.

Switching Between Formulations

Patients currently receiving Vyvgart (efgartigimod alfa-fcab) intravenous (IV) infusion may be switched to Vyvgart Hytrulo for subcutaneous administration. The first subcutaneous dose should be administered one week after the last scheduled IV infusion. Healthcare providers should consult the full Prescribing Information for detailed guidance on making this transition.

Missed Dose Protocol

If a scheduled dose of Vyvgart Hytrulo is missed, it can be administered up to 3 days after the originally scheduled date. After this administration, the patient should resume the original weekly dosing schedule to complete the treatment cycle. If more than 3 days have passed, a healthcare provider should be consulted for instructions on how to proceed.

Safety Alerts

Vyvgart Hytrulo can increase the risk of infection and may cause hypersensitivity reactions. Key safety considerations include:

• Infections: As an IgG neonatal Fc receptor blocker, Vyvgart Hytrulo may lower IgG levels and increase susceptibility to infections. The most common infections observed are urinary tract and respiratory tract infections.
• Hypersensitivity Reactions: Serious reactions such as angioedema and anaphylaxis have been reported. Patients should be monitored during and after administration. If a significant reaction occurs, administration should be discontinued and appropriate therapy initiated.

Frequently Asked Questions

What defines a treatment cycle for Vyvgart Hytrulo?

A treatment cycle consists of four subcutaneous injections, administered once per week for four consecutive weeks.

How does the calculator determine the weekly dose dates?

The calculator adds exactly 7 days to the date of the previous dose to schedule the subsequent three doses in the cycle (e.g., Day 1, Day 8, Day 15, Day 22).

What is the minimum recommended time between treatment cycles?

The safety of initiating a new treatment cycle sooner than 50 days (approximately 7 weeks) from the start of the previous cycle has not been established. The calculator uses this 50-day interval to determine the earliest possible start date for a new cycle.

Why does the calculator ask for the previous cycle's start date?

This optional input allows the tool to perform a safety check and alert the user if the planned start date for the new cycle falls within the 50-day minimum interval from the previous one.

Is the dose of Vyvgart Hytrulo adjusted for body weight?

No, the recommended dose is a fixed 1,008 mg / 11,200 units, regardless of the patient's body weight.

Can I use this calculator for the intravenous (IV) formulation of Vyvgart?

No, this calculator is designed exclusively for the subcutaneous formulation, Vyvgart Hytrulo. The dosing frequency and administration method are different for the IV formulation.

What is the administration time for the injection?

The subcutaneous injection should be administered over a period of 30 to 90 seconds.

Does this tool replace the official Prescribing Information?

No. This tool is for educational and informational purposes only. It is not a substitute for clinical judgment or the official, most current Prescribing Information, which should always be consulted for definitive guidance.

References

• VYVGART HYTRULO (efgartigimod alfa and hyaluronidase-qlhc) Injection Prescribing Information. U.S. Food and Drug Administration. Revised: 06/2023.
• Vyvgart Hytrulo Official Healthcare Professional Website. Argenx.
• Drugs@FDA: FDA-Approved Drugs - Vyvgart Hytrulo. U.S. Food and Drug Administration.