Bylvay (odevixibat)
An approved treatment for Progressive Familial Intrahepatic Cholestasis and Alagille Syndrome.
Drug facts
The same compound appears under different names depending on the context. Here is how to identify Odevixibat wherever you encounter it, plus the key facts at a glance.
- Generic name
- Odevixibat
- Brand name
- Bylvay
- Development code
- A4250
- Drug class
- Ileal bile acid transporter (IBAT) inhibitor
- Manufacturer
- Ipsen
- How it's taken
- Children under 19.5kg use oral pellets of 200mcg or 600mcg, and heavier children and adults use capsules of 400mcg or 1,200mcg.
A once-daily medicine taken with breakfast as pellets sprinkled on food or as capsules. It was the first FDA-approved drug for PFIC, approved July 20, 2021, and covers itch in PFIC from 3 months of age and in Alagille syndrome from 12 months.
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Where Odevixibat fits
One of 2 FDA-approved IBAT inhibitors for itch in PFIC and Alagille syndrome, alongside Livmarli (maralixibat). Bylvay covers PFIC from 3 months and Alagille syndrome from 12 months, while Livmarli covers Alagille syndrome from 3 months and PFIC from 12 months.
How Odevixibat works
In PFIC and Alagille syndrome, bile does not drain properly from the liver, and bile acids build up and cause an intense itch. Normally most bile acids are taken back up in the last part of the small intestine and returned to the liver. Odevixibat blocks the pump that does this, so more bile acids leave in the stool. It treats the itch and does not cure the underlying liver disease.
Side effects and safety
- Liver injury. Liver tests before starting and often during the first 6-8 months. Bylvay is stopped for good after repeated liver test problems, hepatitis that returns on restarting or signs of liver failure.
- Diarrhea. Treatment is paused for ongoing diarrhea and restarted at 40mcg/kg a day once it settles.
- Low vitamins A, D, E and K. Levels are checked before and during treatment. Fractures happened in 5% of people with PFIC and 4% with Alagille syndrome in long-term studies, and treatment may pause for a fracture or bleeding.
- Liver tests at baseline and often in the first 6-8 months
- Vitamins A, D, E and K before and during treatment
- Watch for diarrhea, bleeding or bruising and fractures
Bylvay has no boxed warning, but it must not be used by people who have had liver decompensation. Its warnings cover liver injury, diarrhea and low fat-soluble vitamins A, D, E and K. Across its PFIC and Alagille trials, 6 people had drug-related liver injury, and 2 of them received liver transplants. In the PFIC trial, diarrhea affected 39% at the lower dose and 21% at the higher dose, against 10% on placebo.
This is not a complete list of side effects. Talk to your doctor or pharmacist about what to expect and when to seek medical attention.
Taking Odevixibat
Taken once a day in the morning with a meal. Children under 19.5kg use oral pellets of 200mcg or 600mcg, and heavier children and adults use capsules of 400mcg or 1,200mcg. Pellet capsules are opened and mixed into up to 2 tablespoons of soft food or 5mL of liquid given by oral syringe. They are never swallowed whole. For PFIC the dose starts at 40mcg/kg and can rise to 120mcg/kg after 3 months without improvement, up to 6mg a day.
For Alagille syndrome the dose is 120mcg/kg, and it can drop to 40mcg/kg if not tolerated. Bile acid binders such as cholestyramine are taken at least 4 hours apart from Bylvay.
Availability and cost
Only available as the brand-name product.
Help paying for Bylvay
Pick your insurance to see which help fits. Drugmaker copay cards can't be used with Medicare, Medicaid or TRICARE; charity funds are the usual route there.
- Insurance and case manager help
Enrollment starts at the doctor's office. Patient Access Managers handle benefits checks, prior authorizations and appeals, and Patient Education Liaisons offer education and support.
The official page does not say who qualifies. Ask the program. · source - Copay help
Commercially insured patients may pay as little as $0 per prescription, up to an annual maximum. Not valid with Medicare, Medicaid, Medigap, VA, DoD or TRICARE, or with help from another assistance program or foundation in the same year.
For: private insurance · source - Free medicine program
Patient Assistance Program gives Bylvay free to people without insurance, or whose insurance does not cover it, who meet financial criteria. Requires IPSEN CARES enrollment.
For: no insurance, underinsured · source
Good to know: Call IPSEN CARES at 866-435-5677, weekdays 8am-8pm ET.
- From a charity · PFIC NetworkPFIC Financial Assistance Program fundOpen
Pays for: Uncovered medical expenses (genetic testing, vitamins, travel), insurance premiums and copays, rent or utilities, up to $1,000 per year.
The foundation says: “The PFIC Network accepts applications throughout the year on a rolling basis.” - From a charity · Alagille Syndrome AllianceALGSAssistance Program fundOpen
Pays for: Rent or mortgage, utilities, insurance premiums, counseling, and medical, adaptive or mobility equipment, up to $1,000 per year.
The foundation says: “Apply now (reviewed case by case as funding allows)” - From a charity · HealthWell FoundationAlagille Syndrome Vitamins and Supplements fundOpen
Pays for: Copays, premiums or other treatment costs.
Every program and charity fund for Progressive Familial Intrahepatic Cholestasis →
Access and eligibility
Approved for itch in PFIC from 3 months of age and cholestatic itch in Alagille syndrome from 12 months. It is not recommended for a subgroup of PFIC type 2 with ABCB11 changes that leave no working bile salt export pump (BSEP) protein. It must not be used after liver decompensation, such as bleeding from swollen veins or fluid in the belly.
Source: IPSEN CARES (Bylvay patient support)
Access program details are provided for informational purposes and may vary based on insurance coverage, geographic location, and individual circumstances. Confirm current eligibility directly with the manufacturer or your specialty pharmacy.
Clinical trial results
For PFIC, the PEDFIC 1 trial (NCT03566238) enrolled 62 children aged 6 months to 17 years with PFIC types 1 and 2. They were randomly assigned to 1 of 2 doses or placebo for 24 weeks. Caregivers rated scratching as absent or mild in 35% of checks at the lower dose and 30% at the higher dose, against 13% on placebo. Only the lower dose's gain was clearly beyond chance in that trial.
For Alagille syndrome, the ASSERT trial (NCT04674761) compared Bylvay with placebo for 24 weeks in 52 children. Scratching scores fell 1.7 points on Bylvay against 0.8 on placebo, with about a 1 in 500 chance of being a fluke (p=0.002).
Development history
Albireo Pharma developed odevixibat, and the FDA approved it on July 20, 2021 for itch in PFIC from 3 months of age. On June 13, 2023 the FDA added itch in Alagille syndrome from 12 months. Ipsen acquired Albireo in 2023 and now sells Bylvay. In 2025 the FDA added a rule against use after liver decompensation, along with long-term data from extension studies.
Explore Progressive Familial Intrahepatic Cholestasis and Alagille Syndrome trials
Other Progressive Familial Intrahepatic Cholestasis & Alagille Syndrome treatments
Cholestatic itch in PFIC and Alagille syndrome has 2 FDA-approved IBAT inhibitors: Bylvay (odevixibat), first approved July 20, 2021, and Livmarli (maralixibat), first approved September 29, 2021. Other care includes ursodiol, antihistamines and rifampin, used off-label for itch, plus fat-soluble vitamin supplements. Surgery to divert bile and liver transplant remain options when itch or liver disease cannot be controlled.
Common questions about Odevixibat
▸What is Odevixibat (Bylvay)?
A once-daily medicine taken with breakfast as pellets sprinkled on food or as capsules. It was the first FDA-approved drug for PFIC, approved July 20, 2021, and covers itch in PFIC from 3 months of age and in Alagille syndrome from 12 months.
▸How does Odevixibat work?
In PFIC and Alagille syndrome, bile does not drain properly from the liver, and bile acids build up and cause an intense itch. Normally most bile acids are taken back up in the last part of the small intestine and returned to the liver. Odevixibat blocks the pump that does this, so more bile acids leave in the stool. It treats the itch and does not cure the underlying liver disease.
▸What are the side effects of Odevixibat?
Bylvay has no boxed warning, but it must not be used by people who have had liver decompensation. Its warnings cover liver injury, diarrhea and low fat-soluble vitamins A, D, E and K. Across its PFIC and Alagille trials, 6 people had drug-related liver injury, and 2 of them received liver transplants. In the PFIC trial, diarrhea affected 39% at the lower dose and 21% at the higher dose, against 10% on placebo.
▸How is Odevixibat taken?
Taken once a day in the morning with a meal. Children under 19.5kg use oral pellets of 200mcg or 600mcg, and heavier children and adults use capsules of 400mcg or 1,200mcg. Pellet capsules are opened and mixed into up to 2 tablespoons of soft food or 5mL of liquid given by oral syringe. They are never swallowed whole. For PFIC the dose starts at 40mcg/kg and can rise to 120mcg/kg after 3 months without improvement, up to 6mg a day. For Alagille syndrome the dose is 120mcg/kg, and it can drop to 40mcg/kg if not tolerated. Bile acid binders such as cholestyramine are taken at least 4 hours apart from Bylvay.
▸Is Odevixibat FDA approved?
Yes, Odevixibat (Bylvay) is FDA approved (2021) for the treatment of Progressive Familial Intrahepatic Cholestasis and Alagille Syndrome.
▸How do I give Bylvay pellets to a baby or toddler?
Open the pellet capsule and mix the contents into up to 2 tablespoons of soft food such as applesauce, or into 5mL of liquid given by oral syringe. The pellet capsules are never swallowed whole, and the dose is given in the morning with a meal.
▸What is the difference between Bylvay and Livmarli?
Both block the same bile acid pump in the gut to ease cholestatic itch. Bylvay is approved for PFIC from 3 months and Alagille syndrome from 12 months, while Livmarli covers Alagille syndrome from 3 months and PFIC from 12 months. Bylvay is taken with breakfast, and Livmarli 30 minutes before a meal.
▸Can Bylvay be used for every type of PFIC?
It is not recommended for a subgroup of PFIC type 2 where ABCB11 changes leave no working BSEP protein. Its main PFIC trial enrolled only types 1 and 2, so ask your child's liver doctor how genetic results apply.
Sources and references
Every factual claim on this page is drawn from the public sources listed below. Click any reference to open the original document.
- U.S. National Library of Medicine, DailyMed · 2025-12-29. BYLVAY (odevixibat) capsules and oral pellets: prescribing information. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=0935cd31-3251-4a0a-ac23-25ca4be12be9
- U.S. Food and Drug Administration · 2021-07-20. NDA 215498 approval letter. https://www.accessdata.fda.gov/drugsatfda_docs/appletter/2021/215498Orig1s000ltr.pdf
- U.S. Food and Drug Administration · 2023-06-13. NDA 215498 supplement S-003 approval letter (Alagille syndrome). https://www.accessdata.fda.gov/drugsatfda_docs/appletter/2023/215498Orig1s003ltr.pdf
- ClinicalTrials.gov. This Study Will Investigate the Efficacy and Safety of A4250 in Children With PFIC Types 1 or 2. https://clinicaltrials.gov/study/NCT03566238
- ClinicalTrials.gov. Efficacy and Safety of Odevixibat in Patients With Alagille Syndrome. https://clinicaltrials.gov/study/NCT04674761
- Ipsen. IPSEN CARES support for Bylvay patients and caregivers. https://www.ipsencares.com/bylvay-pt-overview