Ursodeoxycholic acid (Ursodiol)
Ursodeoxycholic acid (UDCA), also known as ursodiol, is a relatively hydrophilic bile acid used primarily for its cytoprotective effects in the biliary system. It protects hepatocytes from toxic hydrophobic bile acids, stimulates bile flow (choleretic), and has immunomodulatory and anti-apoptotic properties. **Clinical Pearl:** Highly effective in the management of chronic hepatitis, cholangitis, and gallbladder sludge. > **Warning:** Contraindicated in patients with complete biliary obstruction.
Mechanism: UDCA is a hydrophilic bile acid that **inhibits ileal absorption** of toxic, hydrophobic bile acids → reduces their concentration in the systemic bile acid pool. Hydrophobic bile acids are toxic to hepatobiliary cell membranes and potentiate cholestasis. UDCA also stimulates **biliary secretion** (choleretic effect), protects hepatocyte membranes from detergent effects, and exerts **immunomodulatory** and **anti-apoptotic** effects on liver cells.
Dosing by species
- Hepatobiliary disease / Cholestasis · 10-15 mg/kg · PO · q24h or divided q12h · Long-term · Administer with food to enhance absorption.
- Hepatobiliary disease / Cholangitis · 10-15 mg/kg · PO · q24h or divided q12h · Long-term · Administer with food to enhance absorption.
Doses are a clinical reference for licensed veterinary professionals. Always confirm against the current label and the individual patient.
Routes of administration
Contraindications
- Complete extrahepatic biliary obstruction
- Biliary fistulas
- Severe acute hepatitis
- Cholecystitis
Adverse effects
- Mild gastrointestinal upset (diarrhea, vomiting)
- Hepatotoxicity (rare, typically only if administered during biliary obstruction)
Drug interactions
- Aluminum-based antacids · May bind to UDCA in the GI tract, decreasing its absorption and efficacy. · moderate
- Cholestyramine · Binds to UDCA, significantly decreasing its absorption. · major
- Colestipol · Binds to UDCA, significantly decreasing its absorption. · major
Monitoring
- Liver enzymes (ALT, AST, ALP, GGT)
- Total bilirubin
- Serum bile acids
- Clinical signs of liver disease (jaundice, vomiting, lethargy)
Overdose
Acute overdosage is unlikely to cause severe toxicity but may result in diarrhea. Treatment is symptomatic and supportive.
VetSheet drug reference is intended for licensed veterinary professionals as a clinical decision-support aid, not a substitute for professional judgement or the manufacturer’s current label.