Carbohydrate chains Extracellular fluid Channel protein Cholesterol Protein Protein Bimolecular lipid layer Cytoskeleton Cytoplasm
Extracellular fluid Channel protein Small lipid-insoluble Lipid bilayer solute Lipid-soluble solutes Cytoplasm A
a As water passes in bulk across a porous membrane, any dissolved solute molecularly small enough to traverse the pores passes in bv filtration Aqueous pores vary in size from membrane to membrane and thus in their individual permeability characteristics for certain drugs and other substances
◼ As water passes in bulk across a porous membrane, any dissolved solute molecularly small enough to traverse the pores passes in by filtration. ◼ Aqueous pores vary in size from membrane to membrane and thus in their individual permeability characteristics for certain drugs and other substances
The majority of drugs today are weak organic acids or bases. Cell membranes are more permeable to the unionized forms of drugs than to their ionized forms
The majority of drugs today are weak organic acids or bases. Cell membranes are more permeable to the unionized forms of drugs than to their ionized forms
The degree of a drugs ionization depends both on the ph of the solution in which it is presented to the biologic membrane and on the pka. Henderson-Hasselbalch equation For an acid. pH=pKa+loglionized conc (salt)]/unionized conc(acid)] For a base pH=pKa+loglunionized conc(base) /[ionized conc (salt)
◼ The degree of a drug’ s ionization depends both on the pH of the solution in which it is presented to the biologic membrane and on the pKa. ◼ Henderson-Hasselbalch equation For an acid: pH=pKa+logionized conc.(salt)/unionized conc.(acid) For a base: pH=pKa+logunionized conc.(base) / ionized conc.(salt)