Which option correctly defines Cmax?

Which option correctly defines Cmax?

• A. Area under the curve
• B. Peak plasma concentration on a measuring curve
• C. Time to onset of action
• D. Minimum effective concentration

Answer: (B)

Cmax is the highest concentration of a drug in plasma reached after dosing, as seen on the concentration–time curve. This peak occurs after the drug has been absorbed but before elimination lowers the level, so it represents the maximum level achieved in the bloodstream. It differs from AUC, which measures total drug exposure over time, not the peak. It also isn’t the onset of action, which is when the drug starts to work, or the minimum effective concentration, which is the lowest level needed for a therapeutic effect. Therefore, the peak plasma concentration on the concentration–time curve is the correct definition.

Cmax is the highest concentration of a drug in plasma reached after dosing, as seen on the concentration–time curve. This peak occurs after the drug has been absorbed but before elimination lowers the level, so it represents the maximum level achieved in the bloodstream. It differs from AUC, which measures total drug exposure over time, not the peak. It also isn’t the onset of action, which is when the drug starts to work, or the minimum effective concentration, which is the lowest level needed for a therapeutic effect. Therefore, the peak plasma concentration on the concentration–time curve is the correct definition.