Cmax

Synonyms

Maximum concentration; Peak concentration

Definition

Plasma concentrations reflect a time curve from the administration of a drug through its peak effect and eventual elimination. The maximum concentration of a drug in blood plasma represents drug’s peak effect. Cmax is one of the primary pharmacokinetic measures for evaluating how the body acts upon a drug.

The same dose of a drug may result on different plasma levels because the body is not a passive recipient. Plasma levels of a drug can be altered by the route of administration, the ease of absorption, the distribution of the drug with the body, the bioavailability or accessible concentration of the drug, and the efficiency with which a drug is metabolized or eliminated.

Common factors that affect plasma levels of a drug could include the size of the molecule and its fat solubility; the patient’s gastric pH, physical health, or age; and the presence of other medications or foods that may expedite or slow absorption from...