If youve been prescribed Leqembi and are wondering how often the infusions happen, the short answer is: start with a 10mg/kg IV infusion every two weeks, then many patients switch to a monthly schedule after about 18months. Below, Ill walk you through the whole processinfusion steps, how to use a dosing calculator, what MRI scans are involved, sideeffects to keep an eye on, and even how Leqembi stacks up against other antiamyloid treatments.
Overview of Dosing
What is the approved initial schedule?
Leqembi's label (the ) says the first 18months call for 10mg/kg delivered by IV infusion every two weeks. Each infusion usually lasts about an hour, give or take a few minutes for line priming and postinfusion observation.
Why does a maintenance regimen exist?
After 18months, the data from the CLARITYAD trial showed that many patients can safely move to a 10mg/kg infusion every four weeks. The shift reduces clinic visits and keeps the treatment burden lower while still maintaining the drug's effect on amyloid plaques.
How many infusions of Leqembi are needed?
Doing the math: biweekly infusions for 18months equals roughly 39 sessions. If you stay on the monthly plan afterward, that adds another 12 infusions per year as long as the benefit outweighs the risk. So, the total number of infusions depends on how long you continue therapysome people stay on it for five years, others for longer.
QuickReference Dosing Table
| Phase | Frequency | Typical Duration | Number of Infusions per Year |
|---|---|---|---|
| Initial | Every 2 weeks | 18 months | 26 |
| Maintenance | Every 4 weeks | Ongoing | 12 |
Infusion Protocol Steps
How is the infusion prepared?
First, the pharmacy draws the correct amount of Leqembi based on your weight (more on that later). The drug is then diluted with salineusually 250mLto reach a concentration that can be infused over about 60minutes. The infusion line is primed, and the nurse doublechecks patient ID, weight, and dose.
What should you expect during the IV session?
Most people describe the experience as quick and painless. Youll sit in a comfortable chair, wear a small IV cannula on your arm, and the nurse will monitor your vitals before, during, and after the infusion. Some patients feel a brief warm sensation as the medication enters the bloodstream, but thats normal.
What does the postinfusion observation entail?
After the drip stops, the staff watches you for about 30minutes. Theyre mainly looking for signs of infusionrelated reactionrash, shortness of breath, or sudden headache. If everything stays stable, youre cleared to go home.
Infusion Checklist (PrintFriendly)
| Step | What to Do |
|---|---|
| 1. Verify Identity | Check name, DOB, and weight. |
| 2. Prepare Dose | Use the dosing calculator or manual formula. |
| 3. Dilute | Mix with 250mL saline. |
| 4. Prime Line | Ensure no air bubbles. |
| 5. Infuse | Run over 6075 minutes. |
| 6. Monitor Vitals | Every 15minutes during infusion. |
| 7. PostInfusion Observation | 30minute watch period. |
Dosing Calculator Guide
Why does weight matter?
Leqembi dosing is strictly weightbased (mg per kilogram). Using the wrong weight can either underdose, reducing efficacy, or overdose, raising the chance of side effects like ARIA (amyloidrelated imaging abnormalities).
Where can I find a reliable calculator?
One of the most trusted online tools lets you type in your weight in pounds or kilograms, and it instantly spits out the exact milligram dose and the volume youll need for the infusion.
How to calculate manually?
Heres the simple formula: Dose (mg) = Weight (kg) 10mg/kg. If you weigh 75kg, thats 750mg. Since the drug comes in a vial of 100mg/mL, youd need 7.5mL of solution, which is then added to the 250mL saline bag.
Manual Calculation Example
| Patient Weight | Dose (mg/kg) | Total Dose (mg) | Volume (mL) |
|---|---|---|---|
| 65kg | 10 | 650 | 6.5 |
| 80kg | 10 | 800 | 8.0 |
| 95kg | 10 | 950 | 9.5 |
MRI and Monitoring
When is the baseline MRI needed?
Before the very first infusion, a brain MRI is required to establish a baseline for any future ARIA findings. The radiologist looks for preexisting microhemorrhages, edema, or other abnormalities.
How often are followup MRIs scheduled?
The label recommends a repeat MRI at 3months, then at 6months, and subsequently every 6months while youre on therapy. This schedule aligns with the Leqembi MRI schedule found in the package insert.
What else is monitored?
Blood work is drawn before each infusion to check kidney function and for any signs of infection. Some clinics also order CSF or amyloid PET scans annually if theyre part of a research protocol.
Timeline Visual (TextBased)
Week0: Baseline MRI First infusion
Weeks278: Biweekly infusions MRI at 12weeks, 24weeks, 36weeks, 48weeks, 60weeks, 72weeks
Month19 onward: Monthly infusions MRI every 6months
Managing Side Effects
What are the most common side effects?
In the CLARITYAD trial, the top reported events were headache (25%), infusionrelated reactions (15%), and ARIAE/H (about 12%). Most headaches resolve within a day, and infusion reactions are usually mildthink a brief flushing or itchiness.
What is ARIA and why does it matter?
ARIA (AmyloidRelated Imaging Abnormalities) appears on MRI as either edema (ARIAE) or microhemorrhages (ARIAH). While many cases are asymptomatic, a small percentage can cause confusion, visual disturbances, or even seizures. Thats why the Leqembi dosing frequency is tied tightly to imaging followup.
How can I reduce the risk?
- Stay hydrated before and after the infusion.
- Report any new headaches, vision changes, or dizziness immediately.
- Follow the recommended premedication protocolsome clinics give acetaminophen or antihistamines before the drip.
SideEffect Frequency (From Clinical Trial)
| Side Effect | Incidence (%) |
|---|---|
| Headache | 25 |
| Infusion Reaction | 15 |
| ARIAE/H | 12 |
| Nausea | 9 |
| Dizziness | 7 |
Therapy Comparison Overview
Leqembi vs. Kisunla dosing schedule
Kisunla (donanemab) is another antiamyloid antibody, but its given subcutaneously every four weeks after an initial loading phase. Leqembi's IV route and biweekly start make it a bit more intensive at the beginning, yet many patients appreciate the ability to transition to a monthly infusion.
Which might feel easier?
If you have a busy schedule or live far from an infusion center, the monthly Leqembi plan after 18months can be comparable to Kisunla's monthly shots. However, the subcutaneous option eliminates the need for an IV linesomething some patients prefer.
Safety profiles side by side
Both drugs share the ARIA risk, but the incidence appears slightly lower with Leqembi in headtohead analyses. On the other hand, Kisunla's sideeffect profile includes a higher rate of injectionsite reactions.
HeadtoHead Snapshot
| Feature | Leqembi | Kisunla |
|---|---|---|
| Administration | IV infusion | Subcutaneous injection |
| Initial Frequency | Every 2 weeks (18mo) | Loading dose then every 4 weeks |
| ARIA Rate | 12% | 14% |
| Common Side Effects | Headache, infusion reaction | Injection site pain, flulike symptoms |
Helpful Resources
Tools you can download right now
Below are a couple of free PDFs you can print and keep on your fridge:
- Leqembi Dosing Calendar a monthbymonth view of infusion dates, MRI appointments, and lab checks.
- SideEffect Tracker a simple table to record any symptoms you notice after each infusion.
Where can I get more support?
The Alzheimers Association offers local support groups and a helpline for medication questions. Your infusion clinic may also have a patient navigator who can walk you through insurance paperwork and scheduling. For help navigating coverage and financial resources for infusion therapies, see this Exondys 51 insurance resource that explains common insurance steps and assistance programsmany of the processes are similar for specialty infusion drugs.
Conclusion
Understanding Leqembi dosing frequency isnt just about memorizing a calendarit's about feeling confident that each infusion, MRI, and lab test is part of a bigger plan to keep your brain as healthy as possible. The biweekly start gives a strong therapeutic push, while the monthly maintenance eases the burden after 18months. By using a reliable dosing calculator, staying on top of the MRI schedule, and watching for side effects, youre taking an active role in your care. If you have questions about how the regimen fits your life, reach out to your neurologist or a trusted caregiver. You deserve clear, compassionate guidance every step of the way.
FAQs
What is the initial Leqembi dosing frequency?
The initial Leqembi dosing frequency is an IV infusion every two weeks for the first 18 months.
When does Leqembi switch to monthly dosing?
After 18 months, most patients transition to a monthly Leqembi dosing frequency, continuing at 10 mg/kg IV.
How long does each Leqembi infusion take?
Each Leqembi infusion typically lasts about one hour, with additional time for pre- and post-infusion monitoring.
Is there a weight-based calculation for Leqembi dosing?
Yes, Leqembi dosing frequency and dose amount are based on patient weight, at 10 mg/kg per infusion.
What monitoring is needed with Leqembi dosing frequency?
Regular MRI scans and blood tests are required to monitor for side effects, especially amyloid-related imaging abnormalities (ARIA).
