What is PBPK and when is it used?

• A. It uses plasma data only and cannot extrapolate.
• B. It ignores tissue distribution.
• C. It is only used for pediatric dosing.
• D. Physiologically based PK uses tissue compartments and physiological parameters to predict PK across species and populations; used for extrapolation and scenario testing.

Answer: (D)

Physiologically based pharmacokinetic modeling uses tissue compartments and physiological parameters to predict PK across species and populations, and is used for extrapolation and scenario testing. By representing the body with organs as interconnected compartments, each with its own blood flow, volume, and tissue-specific properties, PBPK can simulate how a drug distributes, is metabolized, and is cleared in different species, ages, disease states, or formulations. This biologically grounded approach lets us translate animal data to humans, explore dosing in pediatrics or organ impairment, anticipate drug–drug interactions, and test how changes in route or formulation will affect exposure, all without relying solely on plasma data. In contrast, models that rely only on plasma measurements and ignore tissue distribution lack the ability to predict these cross-species or scenario-specific outcomes.