Obeticholic Acid (OCA): FXR Therapy in PBC and Liver Safety Limits

　　1.What It Is and Who It Is For

　　Obeticholic acid(OCA,Ocaliva)is a farnesoid X receptor(FXR)agonist​for adults with primary biliary cholangitis(PBC):

　　add-on when response to ursodeoxycholic acid(UDCA)is inadequate;

　　monotherapy when UDCA is intolerable;

　　not a universal drug for all cholestatic liver diseases;

　　not for complete biliary obstruction.

　　Use outside PBC has been studied,but approval scope varies by region—always follow the latest local label.

　　2.Mechanism:Regulating the Bile-Acid Switch

　　FXR regulates bile-acid synthesis,transport,and enterohepatic circulation.OCA:

　　suppresses de novo bile-acid synthesis;

　　promotes biliary export and reduces toxic hydrophobic bile-acid load;

　　modulates inflammatory and fibrotic signaling indirectly.

　　Biochemical improvement does not automatically equal identical long-term outcomes for every patient.

　　3.Dosing:Stepwise and Liver-Guided

　　Initial

　　5 mg once daily in compensated patients without portal hypertension.

　　After 3 months

　　if ALP and/or bilirubin are inadequately improved and tolerability is acceptable,consider 10 mg once daily.

　　If intolerant

　　reduce frequency or dose,or pause temporarily;

　　stop and evaluate for decompensation,jaundice,portal hypertensive events,or biliary obstruction.

　　Resin interaction

　　separate from bile-acid binders by at least 4 hours,preferably longer.

　　4.Adverse Reactions:Pruritus Leads

　　Common:

　　pruritus,fatigue,abdominal pain,constipation;

　　rash,arthralgia,dizziness.

　　Serious liver signals:

　　worsening LFTs,hyperbilirubinemia;

　　ascites,encephalopathy,variceal bleeding;

　　rare but reported liver failure.

　　Do not continue blindly through hepatic deterioration.

　　5.Contraindications and Cautions

　　Contraindicated in:

　　decompensated cirrhosis;

　　prior decompensation events;

　　compensated cirrhosis with portal hypertension evidence;

　　complete biliary obstruction.

　　Before use:

　　assess liver function,bilirubin,ALP/GGT;

　　image/evaluate for portal hypertension;

　　monitor biochemistry during therapy.

　　6.Special Populations and Storage

　　pregnancy/lactation:individual risk-benefit assessment;

　　overdose:worse liver metrics,jaundice,ascites,portal pressure—supportive care;

　　store 20°C–25°C;short excursions 15°C–30°C;

　　5 mg and 10 mg tablets.

　　7.Regulatory Reality

　　Indication width,warnings,and benefit-risk conclusions differ across markets.Confirm the latest regulator decision and current SmPC/label before prescribing.