The biliary system of the liver, crucial for bile secretion and drug excretion, comprises intrahepatic bile ducts that merge to form the common hepatic duct. This duct, carrying hepatic bile, combines with the cystic duct, draining the gallbladder and forming the common bile duct, which empties into the duodenum. Bile, produced by hepatic cells lining the bile canaliculi, is composed primarily of water, bile salts, pigments, electrolytes, and lesser amounts of cholesterol and fatty acids. Bile production is an active secretion process involving separate processes for organic anions, cations, and polar uncharged molecules.

Drugs excreted through the bile typically have molecular weights above 500 Daltons (Da), while those between 300 and 500 Da are excreted via urine and bile. Any decrease in one excretory route compensates for an increase in the other. Drugs with molecular weights under 300 Da are mainly excreted through the kidneys into urine.

In addition to high molecular weight, biliary excretion requires drugs to possess a strongly polar group. Metabolites like glucuronide conjugates are often more polar than the parent drug. The formation of a glucuronide increases the compound's molecular weight by nearly 200 Da, enhancing its polarity.

Examples of drugs excreted into bile include digitalis glycosides, bile salts, steroids, and indomethacin. Compounds that stimulate bile production also boost the biliary excretion of drugs. Phenobarbital could enhance biliary drug excretion by increasing glucuronide metabolite formation and bile flow. Conversely, cholestasis-causing conditions or compounds that reduce bile flow decrease biliary drug excretion. The administration route may also impact the amount of drug excreted into bile.

From Chapter 6:

article

Now Playing

6.9 : Hepatic Drug Excretion: Influencing Factors

Pharmacokinetics: Drug Excretion and Clearance

35 Views

article

6.1 : Drug Elimination: Overview

Pharmacokinetics: Drug Excretion and Clearance

71 Views

article

6.2 : Elimination Kinetics: First-Order and Zero-Order

Pharmacokinetics: Drug Excretion and Clearance

101 Views

article

6.3 : Renal Drug Excretion: Overview

Pharmacokinetics: Drug Excretion and Clearance

38 Views

article

6.4 : Renal Drug Excretion: Glomerular Filtration

Pharmacokinetics: Drug Excretion and Clearance

53 Views

article

6.5 : Renal Drug Excretion: Tubular Reabsorption

Pharmacokinetics: Drug Excretion and Clearance

36 Views

article

6.6 : Renal Drug Excretion: Tubular Secretion

Pharmacokinetics: Drug Excretion and Clearance

37 Views

article

6.7 : Renal Drug Excretion: Effect of Urine pH, Flow Rate, and Drug pKa

Pharmacokinetics: Drug Excretion and Clearance

47 Views

article

6.8 : Hepatic Drug Excretion: Enterohepatic Cycling

Pharmacokinetics: Drug Excretion and Clearance

43 Views

article

6.10 : Drug Excretion: Pulmonary and Glandular Routes

Pharmacokinetics: Drug Excretion and Clearance

14 Views

article

6.11 : Drug Excretion: Miscellaneous Routes

Pharmacokinetics: Drug Excretion and Clearance

13 Views

article

6.12 : Drug Clearance: Overview

Pharmacokinetics: Drug Excretion and Clearance

21 Views

article

6.13 : Clearance Models: Physiological Models

Pharmacokinetics: Drug Excretion and Clearance

33 Views

article

6.14 : Clearance Models: Compartment Models

Pharmacokinetics: Drug Excretion and Clearance

29 Views

article

6.15 : Clearance Models: Noncompartmental Models

Pharmacokinetics: Drug Excretion and Clearance

18 Views

See More

JoVE Logo

Privacy

Terms of Use

Policies

Research

Education

ABOUT JoVE

Copyright © 2025 MyJoVE Corporation. All rights reserved