What does absorption mean in pharmacokinetics?

What does absorption mean in pharmacokinetics?

• A. The process by which a drug enters the bloodstream from the site of administration
• B. The breakdown of drug in the liver
• C. The elimination of drug by kidneys
• D. The distribution of drug to tissues

Answer: (A)

Absorption is the process by which a drug moves from the site of administration into the bloodstream, making it available for circulation and the rest of the body. This step determines how much and how quickly the dose becomes systemic, a concept captured by bioavailability. In practice, drugs taken by mouth must cross intestinal membranes and may be affected by solubility, formulation, pH, and whether food is present. For administration by injection directly into the bloodstream, absorption is essentially complete because the drug is already in the circulatory system. The other options describe later pharmacokinetic processes: metabolism in the liver breaks down the drug, elimination by the kidneys removes it from the body, and distribution refers to the drug moving from blood into tissues.

Absorption is the process by which a drug moves from the site of administration into the bloodstream, making it available for circulation and the rest of the body. This step determines how much and how quickly the dose becomes systemic, a concept captured by bioavailability. In practice, drugs taken by mouth must cross intestinal membranes and may be affected by solubility, formulation, pH, and whether food is present. For administration by injection directly into the bloodstream, absorption is essentially complete because the drug is already in the circulatory system. The other options describe later pharmacokinetic processes: metabolism in the liver breaks down the drug, elimination by the kidneys removes it from the body, and distribution refers to the drug moving from blood into tissues.