In pharmacology and pharmacokinetics, absorption is the process whereby medicines are transported or taken up from the site of administration (by mouth, inhalation, intravenous or intramuscular injection, etc.) to the blood through capillary, osmotic, solvent, or chemical action in the cells. This could be through the intestinal wall, skin, or mucous membranes.
In specific situations, such as intravenous (IV) therapy, absorption is straightforward and there is less variability, because the medicine goes directly in to the bloodstream. In the case of IV injection, the bioavailability of the compound is 100%.
Absorption is a primary focus in medicines development, as a compound must first be absorbed before any medicinal effects can take place. Moreover, the medicine’s pharmacokinetic profile can be significantly changed by factors that affect absorption.