Systems dynamics in clinical pharmacokinetics. An introduction

Area of Science:

• Pharmacokinetics
• Systems Biology
• Physiological Modeling

Background:

• Pharmacokinetics investigates the body's response to substances, treating it as a system.
• Understanding input-output relationships (dosage rate to blood concentration) is key.
• Residence time distribution is central to pharmacokinetic modeling.

Purpose of the Study:

• To present a systems approach to pharmacokinetics.
• To derive the body's transport function model-independently.
• To illustrate the application of this approach with clinical and computational examples.

Main Methods:

• Model-independent derivation of the body transport function.
• Defining the transport function based on pulmonary and systemic circulation feedback loops.
• Utilizing residence time distributions, transit times, and recirculation.

Main Results:

• Established a systems framework for pharmacokinetics.
• Identified key dynamic parameters: cardiac output, clearance, volume of distribution, mean transit time, and mean residence time.
• Highlighted the importance of mean absorption time and bioavailability for drug absorption.

Conclusions:

• The systems approach provides a comprehensive framework for understanding pharmacokinetics.
• This methodology integrates various physiological parameters to model drug disposition.
• Clinical and computational experiments validate the utility of this systems perspective.