Which statement about absorption is NOT part of absorption?

• A. Route of administration
• B. Bioavailability
• C. Metabolism
• D. Amount of medication that passes through absorbing surfaces

Answer: (C)

Absorption is about how a drug moves from its site of administration into the bloodstream. The route of administration shapes how the drug enters circulation—some routes involve direct entry to the blood, while others pass through tissues and barriers before entering. Bioavailability describes the fraction of the administered dose that actually reaches systemic circulation, which is a key part of the absorption process. The amount of medication that passes through absorbing surfaces reflects the extent of absorption—the portion that successfully crosses membranes to enter the bloodstream.

Metabolism, on the other hand, happens after absorption. It involves chemical changes to the drug (often in the liver) and can reduce or modify the active drug before it circulates. This step is separate from absorption, so the statement about metabolism is not part of the absorption process.