Drug absorption (null)

Drug absorption refers to the **process by which a pharmaceutical compound moves from its site of administration into the bloodstream**, allowing it to reach systemic circulation and ultimately its site of action. This process depends on several factors including route of administration (oral, intravenous, intramuscular, subcutaneous, transdermal), physicochemical properties of the drug (such as solubility and ionization), formulation characteristics (e.g., tablet vs. solution), physiological variables (such as gastrointestinal pH and motility), presence of food or other medications in the GI tract, blood flow at the site of absorption, and patient-specific factors like age and health status[1][2][4][6][8]. Absorption does **not apply to intravenously administered drugs**, since these are delivered directly into systemic circulation. For oral medications—the most common route—absorption primarily occurs in the small intestine due to its large surface area and favorable permeability characteristics. The rate at which a drug dissolves can affect both how quickly it acts and how much reaches systemic circulation ("bioavailability")[1][2]. Drug absorption is **not itself a therapeutic target**, but rather an essential pharmacokinetic concept critical for understanding dosing regimens and predicting therapeutic outcomes. It should not be listed among molecular targets such as receptors or enzymes. "Absorption is defined as the passage of a drug from its site of administration into the plasma...the concept does not apply to intravenously administered drugs..."[8] "Absorption...is accomplished by administering [a] drug in different ways...For drug absorption to occur, [it] must cross biologic barriers..."[4] In summary: "Drug absorption" describes an important *pharmacokinetic process*, **not an individual molecule/receptor/target**, so it should be flagged as incorrect if included among lists intended for actionable biological targets such as receptors or enzymes.

Other names

Absorption (pharmacology)drug uptakepharmaceutical absorption

Not applicable; describes how drugs move into circulation rather than being an actionable biological entity.