About This Dosing Tool
This Inflectra Dosing Calculator is designed for healthcare professionals to determine the appropriate dose and administration schedule for patients based on their weight and clinical indication. The tool calculates both induction and maintenance dosing, estimates vial requirements, and provides key administration details according to the official Prescribing Information.
Outputs Explained
After entering the patient's information, the calculator will generate the following results:
- Calculated Dose: The total dose in milligrams (mg) for a single infusion, based on weight and the standard mg/kg rate for the selected indication.
- Vials Required: The number of 100 mg single-dose vials needed to prepare the infusion. This is calculated by rounding up to the nearest whole vial.
- Volume to Withdraw: The total volume in milliliters (mL) to be withdrawn from the reconstituted vials to achieve the calculated dose. This assumes a standard concentration of 10 mg/mL after reconstitution.
- Dosing Schedule: A clear summary of the induction schedule (Weeks 0, 2, and 6) and the specific maintenance therapy schedule for the chosen indication.
- Administration Notes: Important reminders, such as the requirement to dilute the withdrawn volume into a 250 mL infusion bag of 0.9% Sodium Chloride Injection, USP.
How to Use the Calculator
Follow these simple steps to obtain a dosing recommendation:
- Enter Patient Weight: Input the patient's weight and select the appropriate unit (kg or lbs). The tool will automatically convert lbs to kg for the calculation.
- Select Indication: Choose the relevant clinical indication from the dropdown menu. Options include adult and pediatric Crohn's Disease and Ulcerative Colitis, as well as Rheumatoid Arthritis, Ankylosing Spondylitis, Psoriatic Arthritis, and Plaque Psoriasis.
- Calculate and Review: Click the "Calculate Dose" button. The results will be displayed, providing a comprehensive overview for dose preparation and administration planning.
Dosing Overview
Induction Dosing
For all approved indications, the standard induction dosing schedule for Inflectra is administered as an intravenous infusion at Week 0, Week 2, and Week 6.
Maintenance Dosing
Maintenance therapy begins after the induction phase. The dose and frequency depend on the indication:
- Rheumatoid Arthritis: 3 mg/kg every 8 weeks. The dose may be increased to 10 mg/kg or the frequency increased to every 4 weeks if the clinical response is inadequate.
- Ankylosing Spondylitis: 5 mg/kg every 6 weeks.
- Crohn's Disease, Ulcerative Colitis, Psoriatic Arthritis, Plaque Psoriasis: 5 mg/kg every 8 weeks.
Switching Between Infliximab Products
When switching a patient from a reference infliximab product to Inflectra, it is recommended to maintain the same dose and dosing interval that the patient was receiving previously. The decision to switch should be made by an experienced healthcare provider in consultation with the patient. Always refer to the latest Prescribing Information for complete guidance.
Missed Dose Protocol
If a patient misses a scheduled maintenance dose of Inflectra, the missed dose should be administered as soon as possible. Subsequently, the dosing schedule should be adjusted to maintain the recommended interval from the date of the most recent infusion. Consult the full Prescribing Information for detailed clinical guidance.
Safety Alerts
Inflectra has a Boxed Warning regarding the risk of serious infections and malignancies. Patients should be monitored closely for signs and symptoms of infection during and after treatment. This tool is not a substitute for clinical judgment. Healthcare professionals must review the full Prescribing Information, including all warnings and precautions, before prescribing or administering Inflectra.
Frequently Asked Questions (FAQ)
How is the required number of vials determined?
The calculator determines the total dose in mg and divides it by 100 (the mg content per vial). Since vials cannot be split for future use, the result is always rounded up to the next whole number to ensure enough medication is available for preparation.
What is the concentration of reconstituted Inflectra?
Each 100 mg vial of Inflectra is reconstituted with 10 mL of Sterile Water for Injection, USP, to yield a final concentration of 10 mg/mL.
Can this calculator be used for Remicade® or other infliximab biosimilars?
No. This tool is specifically calibrated for Inflectra. Dosing information, preparation, and administration for other infliximab products may differ. Always use a product-specific calculator or refer to the appropriate Prescribing Information.
Does the calculator handle dose adjustments for Rheumatoid Arthritis?
The calculator provides the initial recommended dose of 3 mg/kg. For patients with an inadequate response, the Prescribing Information allows for titration up to 10 mg/kg or increasing the frequency to every 4 weeks. These adjustments require clinical judgment and are not automatically calculated by the tool.
What is the standard induction schedule for all indications?
The standard induction schedule involves intravenous infusions at Week 0, Week 2, and Week 6.
Why is the maintenance schedule for Ankylosing Spondylitis different?
Clinical trials established that a maintenance dose of 5 mg/kg every 6 weeks is effective for managing Ankylosing Spondylitis, which differs from the every-8-week schedule for most other indications.
Does the tool calculate doses for pediatric patients?
Yes, the calculator includes options for pediatric patients (age 6 years and older) with Crohn's Disease and Ulcerative Colitis, using a dose rate of 5 mg/kg.
What if a patient's weight is outside the tool's limits (e.g., over 300 kg)?
The tool's weight limits (1-300 kg) cover the vast majority of clinical scenarios. For patients outside this range, manual calculation is required. Always verify such calculations and exercise clinical judgment, referencing the Prescribing Information.
How is the final volume for the infusion prepared?
The calculated volume of reconstituted Inflectra is withdrawn from the vials and must be further diluted in a 250 mL infusion bag of 0.9% Sodium Chloride Injection, USP, before administration.
References
- INFLECTRA® (infliximab-dyyb) Prescribing Information. U.S. Food and Drug Administration. Revised: 09/2023.
- Pfizer for Professionals. Inflectra (infliximab-dyyb) HCP Site. Pfizer Inc.
- Rubin DT, Ananthakrishnan AN, Siegel CA, Sauer BG, Long MD. ACG Clinical Guideline: Ulcerative Colitis in Adults. Am J Gastroenterol. 2019;114(3):384-413.
- Singh JA, Saag KG, Bridges SL Jr, et al. 2015 American College of Rheumatology Guideline for the Treatment of Rheumatoid Arthritis. Arthritis Rheumatol. 2016;68(1):1-26.
