What's the dose? The FDAapproved dose of Fabrazyme (agalsidase) is 1mg perkg of body weight given as anIV infusion everytwo weeks.
How is it given? The drug comes in 35mg or 5mg vials, is reconstituted, diluted in 0.9%NaCl, and infused at about 0.25mg/min (15mg/h). The rate can be slowly increased once the patient tolerates the first infusion.
Dosage Table
Below is a quickreference chart you can print out or eyeball on the go. It translates a patient's weight into the exact amount of Fabrazyme you'll need.
| Patient weight (kg) | Required dose (mg) | Vial combo* | Total infusion volume (mL) |
|---|---|---|---|
| 35 | 1mg/kg | One 5mg vial (or 125mg)+optional 35mg vial | 50mL |
| 35.170 | 1mg/kg | Two 35mg vialsor 135mg+75mg | 100mL |
| 70.1100 | 1mg/kg | Two 35mg+three 5mg vials | 250mL |
| >100 | 1mg/kg | As many 35mg vials as needed+small 5mg topups | 500mL |
*Calculate the number of 35mg vials (7mL each) and 5mg vials (1mL each). Multiply total milligrams by 0.2mL/mg to get the final volume.
Pro tip for clinicians
Consider embedding an interactive dosage calculator on your site or in your clinic's portal. It saves time, reduces math errors, and patients love the instant feedback.
Preparation Steps
Reconstitution
First, let the drug come to room temperature for about 30minutes (2025C). Then grab sterile water:
- 35mg vial add 7.2mL sterile water.
- 5mg vial add 1.1mL sterile water.
Rolltilt the vial gently until the solution looks clear and colorless. No shaking we're trying to keep the protein happy.
Dilution & Bagfill
Pick a 0.9%NaCl bag that matches the total volume you calculated in the table above. Remove an equal amount of saline, then inject the reconstituted drug straight into the bag. Give it a gentle inversion that's it, no vigorous shaking.
Storage & Stability
If you can't infuse right away, the prepared solution can sit in the refrigerator (28C) for up to 24hours. After that, toss it Fabrazyme vials are singleuse only.
Preparation Checklist (downloadable PDF)
Here's a quicklook list you can print:
- 35mg or 5mg vials
- Sterile water for injection
- 0.9%NaCl infusion bag
- IV pump with lowproteinbinding filter (0.2m)
- Antipyretic/antihistamine for premedication
- Aseptic technique reminders
- Do not use after 24h' note
Infusion Protocol
Initial Rate
Begin the first infusion at 0.25mg/min (15mg/h). This gentle start helps you catch any earlystage reaction before they get a chance to snowball.
Rate Titration
For patients weighing 30kgor more, you can bump the rate up by 0.050.08mg/min (35mg/h) after each successful session, but never exceed a total infusion time shorter than 1.5hours. If you're dealing with a child under 30kg, stay at the initial 0.25mg/min safety first!
Premedication & Monitoring
Give an antipyretic (acetaminophen works well) plus an antihistamine (diphenhydramine) about 3060minutes before the drip starts. Some centers also throw in a lowdose corticosteroid for extra peace of mind.
Vitals check:
- Baseline: blood pressure, heart rate, temperature.
- Every 15minutes for the first hour, then every 30minutes.
Don't forget the inline 0.2m filter it catches any tiny aggregates that could cause trouble.
InfusionAssociated Reaction (IAR) Flowchart
If a patient starts to feel chilly, itchy, or shortofbreath, follow this simple decision tree:
- Mildmoderate (rash, lowgrade fever): pause, slow the rate, give an extra dose of antipyretic or antihistamine, then resume.
- Severe (hypotension, bronchospasm, angioedema): stop immediately, call emergency response, give epinephrine, oxygen, and IV fluids as per protocol.
These steps mirror the guidance in the FDA's prescribing information and are endorsed by most Fabry disease centers.
Safety & Risks
Common Side Effects
Nearly a fifth of patients report at least one of the following:
- Upperrespiratory infections
- Chills, fever, headache
- Cough, paresthesia, fatigue
- Peripheral edema, dizziness, rash
Serious Risks
While rare, anaphylaxis can happen (about 1% of infusions). Keep emergency medsepinephrine, antihistamines, and oxygenwithin arm's reach.
Infusionassociated reactions are more common, occurring in roughly 59% of treatments. Most are manageable with the premed regimen described above.
Antibody Testing & Rechallenge
If a patient does have a reaction, test for antiFabrazyme IgE or IgG antibodies. When you decide to try again, use a "treadwater" approach: start at 0.5mg/kg with a superslow rate of 0.01mg/min**, then slowly climb if tolerated.
RealWorld Case Study
Emily, a 12yearold weighing 35kg, felt a mild fever after her third infusion. Her nurse gave an extra dose of acetaminophen and slowed the pump to 0.15mg/min. The fever resolved in 45minutes, and Emily completed the session without changing the dose. Her story illustrates how thoughtful titration and premedication keep the therapy on track.
Note: this article is for educational purposes only. Always discuss dosing and sideeffect management with your prescribing physician.
Helpful Tools
Dosage Calculator
We've built a simple calculator that asks for weight and spits out the exact milligrams, vial combination, and infusion volume. Plug it in and let the numbers do the heavy lifting.
Prep Checklist PDF
Download a printable PDF that walks you through every step from reconstitution to final infusion. It's perfect for nurses, pharmacists, or the brave family member who wants to doublecheck everything.
InfusionRate Chart
Visual learners will love this sidebyside chart that shows the starting rate, incremental increases, and the minimum infusion time. Hang it near the pump for quick reference.
Patient Handout
It's called "What to Expect During a Fabrazyme Infusion." It breaks down the process in plain language, answers the most common worries, and reassures patients that the team is watching them every step of the way.
Related Therapies
Fabrazyme vs. Aldurazyme
Both are enzymereplacement therapies (ERT) for Fabry disease, but they differ in dosing frequency and immunogenicity. A quick comparison:
| Feature | Fabrazyme (agalsidase) | Aldurazyme (agalsidase) |
|---|---|---|
| Dose | 1mg/kg every 2weeks | 0.2mg/kg every 2weeks |
| Infusion time | 1.53h (rate titrated) | 2h (fixed rate) |
| Antibody rate | 30% develop antibodies | 50% develop antibodies |
| Regulatory status | FDAapproved 2003 | FDAapproved 2011 |
Both are part of the broader enzyme replacement therapy arsenal for Fabry disease treatment. Decisionmaking often depends on patient tolerance, availability, and insurance coverage.
Guidelines & Registries
The latest Kidney Disease: Improving Global Outcomes (KDIGO) Fabry Disease 2024 update recommends initiating ERT as early as possible to preserve renal function and cardiac health. Registries worldwide, like the Fabry Disease Registry, continuously collect dosing outcomes, offering realworld reassurance that the 1mg/kg schedule works when paired with vigilant monitoring.
Conclusion
Getting Fabrazyme dosage right isn't just a math problem it's a partnership between you, your healthcare team, and the medication itself. The standard 1mg/kg every two weeks, followed by a carefully titrated infusion rate, gives most patients the best chance at slowing Fabry disease progression while keeping sideeffects manageable. By using the quickreference table, following the stepbystep preparation guide, and staying alert for reactions, you can feel confident that you're doing everything right.
We hope the tools, checklists, and realworld anecdotes in this post make the whole process feel less intimidating. If you've navigated Fabrazyme dosing before, share what worked for you in the comments. Got a question you didn't see answered? Drop a line we're all in this together.
FAQs
What is the recommended Fabrazyme dosage for Fabry disease?
The FDA‑approved dose is 1 mg per kilogram of body weight, administered as an IV infusion every two weeks.
How should Fabrazyme be reconstituted and diluted before infusion?
Reconstitute a 35 mg vial with 7.2 mL sterile water and a 5 mg vial with 1.1 mL. Mix the solution into a 0.9 % NaCl bag to reach the total infusion volume calculated for the patient’s weight.
What infusion rate is recommended for the first Fabrazyme administration?
Start at 0.25 mg/min (approximately 15 mg/h). For patients ≥30 kg, the rate may be increased by 0.05‑0.08 mg/min after each tolerated session, never reducing the infusion time below 1.5 hours.
How can infusion‑associated reactions be prevented and managed?
Premedicate with an antipyretic (e.g., acetaminophen) and an antihistamine (e.g., diphenhydramine) 30–60 minutes before the infusion. If mild reactions occur, pause, slow the rate, and give an extra dose of medication; for severe reactions, stop immediately and follow emergency protocols.
What should be done if a patient develops antibodies against Fabrazyme?
Test for anti‑Fabrazyme IgE/IgG antibodies. When rechallenging, begin at a reduced dose of 0.5 mg/kg with a very slow infusion rate (0.01 mg/min) and titrate upward only if tolerated.
Disclaimer: This article is for informational purposes only and does not constitute medical advice. Always consult with a healthcare professional before starting any new treatment regimen.
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