ursodiol
Brand: Actigall, Urso
Prototype Drug
Drug Class: bile acid
Drug Family: GI agent
Subclass: hydrophilic bile acid (ursodeoxycholic acid — UDCA)
Organ Systems: gastrointestinal
Mechanism of Action
Naturally occurring hydrophilic bile acid; replaces toxic hydrophobic bile acids in bile pool reducing cholesterol saturation; hepatoprotective by protecting against hydrophobic bile acid cytotoxicity.
hepatocyte bile acid composition
Indications
- gallstone dissolution (small cholesterol stones)
- primary biliary cholangitis (PBC)
- NAFLD/NASH (uncertain benefit)
- prophylaxis during rapid weight loss or bariatric surgery
- primary sclerosing cholangitis (limited benefit)
Contraindications
- bile duct obstruction
- complete biliary obstruction
- calcified/radiopaque gallstones
- allergy
Adverse Effects
Common
- diarrhea
- GI upset
- hepatotoxicity (rare — paradoxical)
Serious
- hepatotoxicity (advanced liver disease — paradoxical worsening in severe cirrhosis)
Pharmacokinetics (ADME)
| Absorption | ~90% absorbed |
| Distribution | moderate |
| Metabolism | hepatic first-pass |
| Excretion | biliary (enterohepatic recirculation) |
| Half-life | 2.5-5 days |
| Onset | varies |
| Peak | 1-3 hours |
| Duration | months to years |
| Protein Binding | none |
| Vd | moderate |
Drug Interactions
| Drug / Agent | Mechanism | Severity |
|---|---|---|
| cholestyramine/antacids | reduce UDCA absorption — separate by 2 hours | moderate |
| estrogens/clofibrate | increase biliary cholesterol secretion counteracting UDCA effect | moderate |
Nursing Considerations
- PBC: monitor LFTs; treatment must be continued indefinitely
- Gallstone dissolution: requires months to years; stones must be radiolucent (cholesterol, not calcium)
- Separate from cholestyramine by 2 hours (reduced absorption)
Clinical Pearls
- Gallstone dissolution: UDCA reduces cholesterol saturation by 30-40%; recurrence after discontinuation is common
- PBC: reduces LFTs and slows disease progression but does not normalize liver histology in all patients
Safety Profile
Pregnancy use-with-caution
Lactation use-with-caution
Renal Adjustment Not required
Hepatic Adjustment Not required
TDM Not required
Concordance Terms
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