Physiologically based pharmacokinetic model for digoxin distribution and elimination in the rat

Area of Science:

• Pharmacokinetics and Drug Metabolism
• Physiology
• Toxicology

Background:

• Digoxin pharmacokinetics are complex, involving distribution, metabolism, and excretion.
• Understanding digoxin's organ-specific distribution and clearance is crucial for therapeutic management.

Purpose of the Study:

• To develop a plasma flow rate-limited pharmacokinetic model for digoxin in rats.
• To describe digoxin distribution in key organs (heart, liver, kidneys, skeletal muscle, GI tract).
• To incorporate renal, hepatic, and GI clearance, secretion, and reabsorption mechanisms.

Main Methods:

• Development of a plasma flow rate-limited pharmacokinetic model.
• Simulation of digoxin concentrations in various rat tissues after intravenous administration.
• Model validation using experimental data from normal, bile duct-ligated, and ureter-ligated rats.

Main Results:

• Predicted digoxin concentrations in plasma, heart, liver, and skeletal muscle aligned with experimental observations.
• The model successfully described digoxin pharmacokinetics in rats with altered renal and hepatic function.
• High agreement was observed between predicted and measured urinary excretion rates.

Conclusions:

• The developed pharmacokinetic model accurately describes digoxin distribution and elimination in rats.
• The model provides a valuable tool for predicting digoxin behavior under various physiological and pathological conditions.
• This research enhances understanding of digoxin's complex pharmacokinetic profile.