Abstract
Distribution is the process by which a drug leaves the bloodstream and is delivered to body tissues, including the target organ. Diffusion is typically uneven throughout the body, chiefly because of differences in perfusion rate in the various organs and tissues. Once absorbed, most drugs do not spread evenly throughout the body. Hydrophilic drugs tend to stay within the blood and the interstitial space. Hydrophobic drugs tend to concentrate in fatty tissues. Other drugs may concentrate mainly in only one small part of the body if the tissues there have a special attraction for and ability to retain the drug. Regional differences in pH and membrane permeability also play a role in differential distribution. However, in theory, a drug will distribute from the main circulation into capillaries and then equilibrate into extracellular spaces and then intracellular spaces of organs and tissues. This movement of a drug throughout the body occurs through body water compartments after a drug is dissolved and absorbed.
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Wotring, V.E. (2012). Distribution. In: Space Pharmacology. SpringerBriefs in Space Development. Springer, Boston, MA. https://doi.org/10.1007/978-1-4614-3396-5_3
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