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# Ursodeoxycholic Acid
## Overview
Ursodeoxycholic acid (ursodiol) is a naturally occurring hydrophilic bile acid that decreases the cholesterol content of bile and bile stones by suppressing hepatic synthesis and secretion of cholesterol and inhibiting intestinal absorption.
## Primary Indications
* **Primary Biliary Cholangitis (PBC):** Treatment of patients with PBC.
* **Gallstone Dissolution:** Selected patients with radiolucent, non-calcified gallbladder stones.
* **Cholestasis:** Off-label use in various cholestatic liver diseases (e.g., cystic fibrosis-related liver disease, intrahepatic cholestasis of pregnancy).
## Adult Dosing
* **Primary Biliary Cholangitis:** 13–15 mg/kg/day orally in 2–4 divided doses.
* **Gallstone Dissolution:** 8–10 mg/kg/day orally in 2–3 divided doses.
* *Note: Dosing regimens vary based on clinical guidelines; always verify against institutional protocols.*
## Pediatric Dosing
* **Cholestasis associated with Cystic Fibrosis:** 20–30 mg/kg/day orally in 2–3 divided doses.
* **General Pediatric Cholestasis:** 10–20 mg/kg/day orally in 2–3 divided doses.
## Dose Adjustments
* **Hepatic Impairment:** No specific dose adjustment defined for mild-to-moderate impairment, but use with caution in advanced cirrhosis due to potential for accumulation.
* **Renal Impairment:** No standard adjustments; monitor closely in severe renal failure.
## Contraindications
* Complete biliary obstruction.
* Calcified or radiopaque gallstones.
* Non-functioning gallbladder.
* History of hypersensitivity to bile acids.
* Acute cholecystitis, cholangitis, biliary obstruction, or biliary-gastrointestinal fistula.
## Adverse Effects
* **Common:** Headache, dizziness, diarrhea (dose-dependent), nausea, abdominal pain.
* **Serious:** Worsening of liver disease (rare), calcification of gallstones.
## Key Drug Interactions
* **Aluminum-based antacids/Cholestyramine/Colestipol:** May sequester ursodiol and reduce absorption. Administer at least 2 hours before or after these agents.
* **Estrogens/Oral Contraceptives/Clofibric acid derivatives:** May increase hepatic cholesterol secretion and counteract the therapeutic efficacy of ursodiol for gallstone dissolution.
* **Cyclosporine:** May increase cyclosporine levels; monitor closely.
## Monitoring
* **Baseline:** Liver function tests (LFTs) (ALT, AST, Alkaline Phosphatase, Bilirubin).
* **During Therapy:** Repeat LFTs every 3 months for the first year, then every 6 months thereafter. Monitor for clinical improvement of pruritus or cholestatic markers.
* **Gallstone dissolution:** Perform ultrasound every 6–12 months to confirm efficacy.
## Clinical Pearls
* **Efficacy:** Ursodiol is significantly more effective in early-stage PBC.
* **Non-responders:** Up to 40% of patients with PBC may have an incomplete biochemical response, necessitating adjunctive therapy (e.g., obeticholic acid or fibrates).
* **Pregnancy/Lactation:** Generally considered safe and often used for intrahepatic cholestasis of pregnancy, but consult current clinical guidelines.
* **Dosing Compliance:** Frequent dosing is required to maintain therapeutic bile acid concentration levels.
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**Educational Disclaimer:** This information is for educational purposes only and does not constitute medical advice. Dosing and clinical practices may vary by institution and patient-specific factors. Always verify prescribing information, contraindications, and drug interactions via current, authoritative resources (e.g., Lexicomp, Micromedex, or the official FDA package insert) before prescribing or administering medication.
