ABSTRACT
As drugs move to their target receptors, they occupy sites other than the blood. In some they bind to tissue or intracellular proteins, which effectively ‘takes them out of solution’ and allows further drug to enter the tissue or cellular space because the concentration gradient is maintained. In others, because of pH changes (see above), they change their ionization characteristics and become ‘trappexd’. To calculate the serum concentration resulting from a given dose of drug would therefore require a knowledge of all the various binding characteristics, tissue types, blood flows, dissociation constants, and solubilities.
