About This Tool

This Rystiggo (rozanolixizumab-noli) Dosing Calculator for gMG calculator is a support resource for healthcare professionals to determine the appropriate weekly dose for adult patients with generalized myasthenia gravis (gMG). It aligns with the weight-based dosing schedule specified in the FDA-approved Prescribing Information. This tool simplifies the process of calculating dose, volume, and vial requirements to support accurate preparation and administration.

Outputs Explained

Upon entering a patient's weight, the calculator provides three critical outputs for a single weekly administration:

• Total Weekly Dose (mg): This is the total amount of rozanolixizumab-noli to be administered, determined by the patient's weight tier.
• Total Volume for Infusion (mL): Calculated based on the drug's concentration of 140 mg/mL. This value indicates the total volume of the drug product to be drawn up for the subcutaneous infusion.
• Number of Vials Required: This value indicates how many 280 mg single-dose vials are needed to prepare the total weekly dose.

How to Use the Calculator

Follow these simple steps to determine the patient-specific dosing information:

1. Select Weight Unit: Choose between kilograms (kg) or pounds (lbs) using the toggle button.
2. Enter Patient Weight: Input the patient's current body weight into the designated field.
3. Calculate: Click the "Calculate Dose" button to generate the results. The tool will display the dose, volume, and required vials for one weekly administration.
4. Reset: Click the "Reset" button to clear all inputs and results to start a new calculation.

Dosing Overview for gMG

Rystiggo is administered as a subcutaneous infusion once weekly for a 6-week treatment cycle. The dose is dependent on the patient's body weight, as outlined below.

The decision to initiate subsequent treatment cycles should be based on a thorough clinical evaluation of the patient's condition and treatment response.

Switching Therapies

There is no specific guidance provided in the Prescribing Information on switching between Rystiggo and other gMG therapies. Decisions regarding washout periods or overlapping treatments should be based on the half-life and mechanism of action of the other therapy, as well as individual patient factors and expert clinical judgment.

Missed Dose Protocol

If a scheduled dose of Rystiggo is missed, it should be administered as soon as possible. Thereafter, the regular weekly dosing schedule should be resumed from the date of the most recent dose. Do not administer two doses at the same time to make up for a missed dose.

Key Safety Alerts

Use of Rystiggo is associated with important safety considerations. This is not a complete list. Always consult the full Prescribing Information for comprehensive safety data.

• Infections: Rystiggo may increase the risk of infections. Monitor patients for clinical signs and symptoms. The most common infections observed in clinical trials included upper respiratory tract infections and COVID-19.
• Aseptic Meningitis: Cases have been reported. Signs and symptoms may include severe headache, nuchal rigidity, and photophobia. If suspected, perform a diagnostic workup and treat accordingly.
• Hypersensitivity Reactions: Reactions such as angioedema and rash can occur. If a severe reaction occurs, discontinue the infusion and institute appropriate therapy.

Frequently Asked Questions (FAQ)

What concentration is used for the volume calculation?

The calculator uses the standard concentration of Rystiggo, which is 140 mg of rozanolixizumab-noli per 1 mL of solution.

How many milligrams are in a single Rystiggo vial?

Each single-dose vial of Rystiggo contains 280 mg of rozanolixizumab-noli in 2 mL of solution.

What dose does a patient weighing exactly 50 kg receive?

A patient weighing exactly 50 kg falls into the "50 kg to less than 100 kg" tier and will receive the 560 mg weekly dose.

Does the calculator adjust for renal or hepatic impairment?

No. The calculator's logic is based solely on patient weight per the Prescribing Information. No dose adjustments are recommended for patients with renal or hepatic impairment.

What is a full treatment cycle?

A treatment cycle consists of one subcutaneous infusion administered once per week for a total of six weeks.

Can this calculator be used for pediatric patients?

The safety and effectiveness of Rystiggo have not been established in pediatric patients. The calculator is intended for dosing adult patients with gMG according to the approved label.

How is the dose administered?

Rystiggo is administered as a subcutaneous infusion using an infusion pump. Refer to the full Prescribing Information for detailed administration instructions.

Why might the tool show a warning note?

The tool may display a warning for weights outside the typical clinical range (e.g., under 30 kg or over 250 kg) to prompt the user to double-check the entered value for accuracy, as dosing at extreme weights has not been extensively studied.

References

• RYSTIGGO® (rozanolixizumab-noli) Prescribing Information. UCB, Inc. Smyrna, GA. https://www.ucb-usa.com/RYSTIGGO-pi.pdf
• U.S. Food and Drug Administration. Drugs@FDA: RYSTIGGO. https://www.accessdata.fda.gov/drugsatfda_docs/label/2023/761291s000lbl.pdf
• UCB. RYSTIGGO® Healthcare Professional Site. https://www.rystiggohcp.com/
• Bril V, Drużdż A, Grosskreutz J, et al. Safety and efficacy of rozanolixizumab in patients with generalised myasthenia gravis (MycarinG): a randomised, double-blind, placebo-controlled, adaptive phase 3 study. Lancet Neurol. 2023;22(5):383-394. doi:10.1016/S1474-4422(23)00077-9