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11 Cards in this Set
- Front
- Back
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Distribution
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Reversible transfer between vascular and extra-vascular fluids in systemic admin.
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Drug Distribution Processes
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Drug may: exit vascular space (blood), enter extra-vascular space (ISF), enter tissue cells (ICF) from ISF, return to vascular space from ISF.
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Distribution Factors
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Drug properties (size, lipophilicity, ionization), cap endo, protein binding.
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Vascular Fluids
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Blood (plasma + suspended molecules), plasma (dissolved molecules in blood), serum (plasma minus fibrinogen or clotting factors).
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Drug Regions of Transport
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Macromolecules confined to plasma. Polar drugs may enter ISF. Lipophilic drugs found in extracellular (plasma + ISF) and intracellular fluid.
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Kidney Distribution
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Fenestrated cap endo, high hydrostatic pressure (filtration), rapid distribution.
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Liver Distribution
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Discontinuous caps / sinusoids. Lg. molecules may diffuse from blood.
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Brain Distribution
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V. tight junc. cap endo. Pericytes + astrocytes add'l barriers. BBB restricts entry: transcellular lipophil. pathway limited by efflux, or polar receptor-mediated transcytosis.
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Volume of Distribution
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Extent of dist. Depends on perfusion. Total body water 40 L: Plasma 3L, ISF 9 L, ICF 28 L. Inversely related to plasma conc.
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Ionization and Vd
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Both forms dist. to ISF (unionized slightly favored). Only unionized form enters ICF.
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Protein Binding
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Reversible formation of drug-protein complex. Albumin, glycoprotein, globulins. Total plasma conc. = free + bound drug. Only free drug distributes.
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