biokinetics

Biokinetics is the study of how substances move through and are processed by living organisms. It focuses on the fate of chemicals, drugs, and radionuclides as they enter the body, travel among tissues, undergo transformation, and are eliminated. Common concerns include absorption, distribution, metabolism, and excretion (ADME), as well as tissue binding and excretion pathways.

Researchers use experimental data and mathematical models to describe concentration-time profiles. The frameworks include compartmental models, in which the body is simplified into interconnected compartments, and physiologically based pharmacokinetic models that reflect organ sizes, blood flows, and metabolic capacities. These models help translate lab findings to whole-organism predictions and support dose setting and risk assessment.

Applications span pharmacology, toxicology, environmental health, and regulatory science. Biokinetics informs drug development, dosing regimens, and safety evaluations; it supports risk assessment for pollutants, pesticides, and radionuclides; and it underpins exposure assessment in occupational and environmental contexts.

Key metrics include half-life, clearance, volume of distribution, and bioavailability; rate constants and lag times may also be reported. In vitro–in vivo extrapolation and sensitivity analyses address uncertainty and interindividual variability. While biokinetics overlaps with pharmacodynamics, which studies the effects of substances, the two disciplines together define how dose translates into response.

In some contexts, biokinetics is used in movement sciences to describe body mechanics; this article focuses on the disposition of substances in living systems.