Physiological Pharmacokinetic Models: Blood Flow-Limited Versus Diffusion-Limited Models

Physiological models generally postulate a swift drug distribution between tissue and venous blood.

Rapid drug equilibrium assumes quick drug diffusion and non-restricted drug permeation across the cell membrane.

In flow-limited models without drug binding, the tissue drug concentration mirrors the venous blood exiting the tissue.

Drugs like lidocaine and nicotine are illustrated using a flow-limited model.

The diffusion-limited or membrane-limited model is a more intricate physiological model variant.

Here, the cell membrane poses a barrier to drug permeation.

The swift blood flow and gradual drug permeation establish a drug concentration gradient between tissue and venous blood.

As per this approach, the drug's cell membrane permeation determines its diffusion rate into tissue.