How is absorption defined in pharmacology?

Absorption in pharmacology refers specifically to the process by which a drug enters the bloodstream following administration. Once a medication is taken, whether orally, intravenously, or via another route, it must be absorbed into the circulatory system in order to exert its therapeutic effects. This process can vary based on several factors, including the formulation of the drug, the route of administration, and the physiological characteristics of the individual, such as gastrointestinal pH or blood flow.

Understanding absorption is crucial for determining the onset, intensity, and duration of a drug's action. It sets the fundamental stage for drug distribution and metabolism, which are subsequent processes that affect how the drug behaves within the body. Recognizing that absorption is about the drug entering the bloodstream clarifies its critical role in pharmacokinetics.