Which term is used to describe the measured amount of a drug in a given medium?

• A. Dose
• B. Medication Concentration
• C. Bioavailability
• D. Pharmacodynamics

Answer: (B)

The measured amount of a drug in a given medium is described by its concentration—the amount present per unit of volume in that medium. In the provided choices, medication concentration fits this idea because it specifies how much drug is actually found in the medium (for example, the plasma or a solution). Dose refers to the total amount given, not what’s present in the medium. Bioavailability describes the fraction of the dose that reaches systemic circulation, not a measurement in a specific medium. Pharmacodynamics concerns the drug’s effects on the body, not its quantity in a medium. For example, a plasma concentration of 7 mg/L reflects the drug concentration in plasma.