The total drug exposure your body receives over time—calculated from a graph of blood levels, it captures both how high levels get and how long they last.Area under the concentration-time curve (AUC) is the fundamental pharmacokinetic measure of total systemic drug exposure. AUC₀₋∞ represents total exposure from administration to complete elimination; AUC₀₋τ represents exposure within a dosing interval. For antimicrobial peptides, the AUC/MIC ratio predicts efficacy. For peptide therapeutics generally, AUC determines whether sufficient receptor engagement occurs for therapeutic effect. AUC is influenced by dose, bioavailability, clearance, and volume of distribution.