Free drugs, distribution processes

Chirality does not really become a significant factor unless enantioselectivity exists in processes such as active transport. The distribution of a drug can be markedly affected by its ability to bind to plasma proteins since only a free drug is able to cross... 

The rationaie for measuring concentrations of drugs in piasma, serum, or biood is that concentration-response reiationships are often iess variabie than are dose-response reiationships (2). This is true because indi-viduai variation in the processes of drug absorption, distribution, and eiimination affects dose-response reiationships, but not the reiationship between free (nonprotein-bound) drug concentration in piasma water and intensity of effect (Figure 2.1). 

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