Odevixibat (Bylvay) is a selective ileal bile acid transporter (IBAT) inhibitor, indicated for the treatment of pruritus associated with progressive familial intrahepatic cholestasis (PFIC) and Alagille syndrome (ALGS).

What Are the Side Effects of Odevixibat (Bylvay)?

In PFIC Patients

Gastrointestinal Reactions: Diarrhea (39%), vomiting (17%), abdominal pain (13%).

Liver Function Abnormalities: Elevated transaminases (13%), elevated bilirubin (11%).

Others: Fat-soluble vitamin deficiency (16%), splenomegaly (11%).

In ALGS Patients

Core Symptoms: Diarrhea (29%), abdominal pain (14%), weight loss (6%).

Bleeding-Related: Hematoma (9%), which may be associated with vitamin K malabsorption.

Serious Side Effects of Odevixibat (Bylvay) That Require Vigilance

Risk of Hepatotoxicity

Clinical Manifestations: Drug-induced liver injury (DILI), elevated liver enzymes, and in rare cases, liver transplantation may be required.

Monitoring Requirements: Conduct regular tests for alanine transaminase (ALT), aspartate transaminase (AST), bilirubin, and international normalized ratio (INR) before medication administration and during the initial treatment phase (6-8 months). If hepatitis symptoms occur or liver function remains abnormal, dosage reduction or permanent discontinuation of treatment is necessary.

Contraindicated Populations: Contraindicated in patients with a history of or active liver decompensation (e.g., ascites, hepatic encephalopathy).

Diarrhea and Dehydration

Management Recommendations: For mild cases, fluid replacement is required; for persistent diarrhea, medication should be interrupted, and after symptom relief, restart at a dose of 40 mcg/kg and gradually increase the dosage.

High-Risk Populations: The incidence of diarrhea can reach 21%-39% in PFIC patients and approximately 29% in ALGS patients.

Fat-Soluble Vitamin Deficiency

Risk Factors: Odevixibat inhibits the reabsorption of bile acids, which may affect the absorption of vitamins A, D, E, and K.

Monitoring and Intervention: Measure serum levels of these vitamins at baseline and during the treatment course; supplementation is required if deficiency occurs. If bleeding (e.g., epistaxis, gingival bleeding) occurs, discontinue the medication immediately and optimize vitamin replacement therapy.

Precautions for Odevixibat (Bylvay) Administration

Administration Methods

Capsules: Swallow whole, or open and sprinkle the contents on soft food (e.g., applesauce).

Oral Granules: Must be mixed with liquid and administered via a syringe; swallowing the capsule shell directly is avoided.

Drug Interactions

Bile Acid Sequestrants (e.g., cholestyramine): Administration must be separated by a 4-hour interval; otherwise, the efficacy of odevixibat will be reduced.

Special Populations

Pregnant Women: Animal studies have shown a risk of causing cardiac malformations; odevixibat is contraindicated during pregnancy.

Pediatric Patients: Suitable for PFIC patients aged ≥ 3 months and ALGS patients aged ≥ 12 months.

Patients with Hepatic Impairment: Close monitoring is required for patients with cirrhosis or portal hypertension.

Storage and Follow-Up

Storage Conditions: Store at room temperature (20-25°C).

Long-Term Management: Regularly assess the degree of pruritus relief, liver function, and nutritional status, and be alert to delayed side effects.