About This Guide

This guide provides supplementary clinical information for the Vyvgart (efgartigimod) Dosing Calculator. It outlines key dosing considerations for generalized myasthenia gravis (gMG) and chronic inflammatory demyelinating polyneuropathy (CIDP) based on the approved prescribing information. This information is intended for healthcare professionals and is not a substitute for clinical judgment.

Calculator Outputs Explained

The tool calculates the appropriate dose and provides administration details based on your inputs. The key outputs are:

• For gMG (Intravenous): A patient-specific, weight-based dose (10 mg/kg) in milligrams, along with instructions for dilution and infusion over 60 minutes.
• For gMG (Subcutaneous): A fixed dose of 1,008 mg efgartigimod alfa and 11,200 units hyaluronidase, with instructions for subcutaneous injection.
• For CIDP (Subcutaneous): A fixed dose of 1,008 mg efgartigimod alfa and 11,200 units hyaluronidase, noting the induction and maintenance dosing schedule.

How to Use the Calculator

Follow these steps to determine the recommended dosing regimen:

1. Select the Indication: Choose either generalized myasthenia gravis (gMG) or chronic inflammatory demyelinating polyneuropathy (CIDP).
2. Select the Formulation (for gMG only): If gMG is selected, choose between Intravenous (IV) or Subcutaneous (SC) administration. This option is not available for CIDP, which uses the SC formulation exclusively.
3. Enter Patient Weight (for gMG IV only): If the IV formulation for gMG is selected, enter the patient's weight. You can input the value in kilograms (kg) or pounds (lbs). The tool will automatically convert lbs to kg for the calculation.

Dosing Overview

Generalized Myasthenia Gravis (gMG)

Dosing for gMG is administered in treatment cycles, with subsequent cycles initiated based on clinical evaluation.

• Intravenous (IV) Formulation: The recommended dose is 10 mg/kg administered as an intravenous infusion over one hour, once weekly for 4 weeks. For patients weighing 120 kg or more, the total dose should not exceed 1200 mg per infusion.
• Subcutaneous (SC) Formulation: The recommended dose is 1,008 mg / 11,200 units administered as a subcutaneous injection over 30-90 seconds, once weekly for 4 weeks.

Chronic Inflammatory Demyelinating Polyneuropathy (CIDP)

Dosing for CIDP involves an induction phase followed by a maintenance phase.

• Induction Dosing: The recommended loading dose is 1,008 mg / 11,200 units (SC) administered once weekly for 4 weeks.
• Maintenance Dosing: Following the induction phase, a maintenance dose is administered weekly. The maintenance dosing frequency is individualized based on clinical response.

Switching Formulations

When switching between VYVGART (IV) and VYVGART HYTRULO (SC), the next scheduled dose should be administered one week after the last dose of the previous formulation. The new dosing regimen should then be followed as recommended for the new formulation.

Missed Dose

If a scheduled dose is missed, it may be administered up to 3 days after the scheduled date. Afterward, resume the original weekly dosing schedule until the treatment cycle is complete. Always consult the full prescribing information for detailed guidance.

Safety Alerts

VYVGART and VYVGART HYTRULO may increase the risk of infection. The most common adverse reactions are respiratory tract infection, headache, and urinary tract infection.

Frequently Asked Questions (FAQ)

Why is patient weight required for the IV formulation but not the SC?

The intravenous formulation (VYVGART) dose is calculated based on body weight (10 mg/kg). The subcutaneous formulation (VYVGART HYTRULO) is a fixed-dose combination product that provides comparable exposure to the weight-based IV dose across a range of body weights and is therefore not weight-dependent.

What is the dosing frequency for the initial treatment cycle?

For both gMG and CIDP, the initial (or induction) treatment cycle consists of one administration weekly for four consecutive weeks.

How is the maintenance dose determined for CIDP?

Following the 4-week induction phase for CIDP, a maintenance dose is administered weekly. The prescribing physician may individualize this frequency based on the patient's clinical response and needs.

What is VYVGART HYTRULO?

VYVGART HYTRULO is the brand name for the subcutaneous formulation. It contains efgartigimod alfa (the active ingredient in VYVGART) co-formulated with recombinant human hyaluronidase PH20, which facilitates the subcutaneous delivery of large volumes of medication.

Can this calculator be used for pediatric patients?

No. The safety and effectiveness of VYVGART and VYVGART HYTRULO have not been established in pediatric patients. This calculator is for adult patients only.

What diluent is used for the IV infusion?

The calculated dose of VYVGART should be diluted in 125 mL of 0.9% Sodium Chloride Injection, USP.

Does the calculator account for renal or hepatic impairment?

No dose adjustments are needed for patients with mild hepatic impairment or mild to moderate renal impairment. However, this calculator does not provide specific recommendations for these populations. Clinicians should consult the full Prescribing Information and use their clinical judgment.

How is the IV dose administered?

The diluted IV solution is administered as an intravenous infusion over 60 minutes.

How is the SC dose administered?

The SC formulation is administered as a subcutaneous injection into the abdomen over a period of 30 to 90 seconds.

References

1. VYVGART® (efgartigimod alfa-fcab) US Prescribing Information. FDA.
2. VYVGART® HYTRULO (efgartigimod alfa-fcab and hyaluronidase-qvfc) US Prescribing Information. FDA.
3. argenx. Official Manufacturer Website.
4. VYVGART (efgartigimod alfa) Summary of Product Characteristics. European Medicines Agency.