What is the term for the passage of medication molecules into the bloodstream from the site of administration?

The term that describes the passage of medication molecules into the bloodstream from the site of administration is absorption. This process involves the movement of drugs from their site of administration, whether that be oral, intravenous, intramuscular, or topically applied, into the circulatory system.

During absorption, several factors can influence how quickly and effectively a medication enters the bloodstream, including the formulation of the drug, the route of administration, and the presence of food in the stomach. For example, medications taken orally must first dissolve in the gastrointestinal tract before they can be absorbed into the bloodstream, which can take some time.

Understanding absorption is crucial for nursing practice because it helps determine how often a medication needs to be administered and under what conditions to achieve the desired therapeutic effect. This is different from distribution, which refers to how the drug is dispersed throughout the body after it enters the bloodstream, metabolism, which is the process of chemical alteration of the drug by the body, and excretion, which involves the elimination of the drug from the body. Each of these processes plays a distinct role in pharmacokinetics, but absorption specifically pertains to the entry of the drug into the vascular system.