What is the term for the entry of a therapeutic agent into the bloodstream?

The entry of a therapeutic agent into the bloodstream is referred to as absorption. This process occurs after a drug is administered and involves the movement of the drug from its site of administration into the circulatory system. During absorption, various factors can influence the rate and extent to which a drug enters the bloodstream, such as the formulation of the drug, the route of administration (e.g., orally, intravenously, intramuscularly), and the physiochemical properties of the drug.

Once a drug is absorbed into the bloodstream, it can then be distributed throughout the body, where it exerts its therapeutic effects. Understanding absorption is critical in pharmacology as it impacts the onset of action and overall efficacy of therapeutic agents.

The other terms mentioned also play significant roles in pharmacology: metabolism refers to the chemical modifications made to the drug by the body, distribution is the process by which a drug is transported throughout the body, and elimination involves the removal of the drug from the body. However, none of these processes specifically describe the initial entry of the drug into the bloodstream, which is the essence of absorption.