Mean time parameters in pharmacokinetics. Definition, computation and clinical implications (Part I)

Area of Science:

• Pharmacokinetics
• Pharmacometrics
• Drug Metabolism and Disposition

Background:

• Mean time parameters quantify the average duration of kinetic events in pharmacokinetic processes.
• Numerous mean time parameters exist, necessitating a focus on the most relevant ones.

Purpose of the Study:

• To formally define and discuss key mean time parameters: mean residence time (MRT), mean transit time (MTT), and mean arrival time (MAT).
• To explore the theoretical underpinnings and evaluation methods for these pharmacokinetic parameters.
• To highlight the clinical relevance and applications of mean time parameters in drug development and patient care.

Main Methods:

• Definition of core relationships for mean time parameters in stochastic and non-stochastic systems.
• Description of evaluation methods, including the role of AUMC/AUC for MRT.
• Discussion of kinetic spaces and specific pharmacokinetic models.

Main Results:

• Formal definitions and evaluation methods for MRT, MTT, and MAT are presented.
• The relationship between mean time parameters and drug absorption, distribution, elimination, and accumulation is explored.
• Limitations and assumptions associated with mean time parameter usage are identified.

Conclusions:

• Mean time parameters are essential for understanding drug disposition and kinetics.
• Proper interpretation of mean time parameters aids in predicting and evaluating pharmacokinetic data.
• The study clarifies the definition and application of MRT, MTT, and MAT in pharmacokinetics.