Question

I was wondering how the area under the curve in the case of a conc against time plot would be equal to the total exposure in the body? I know that this area is integrated using

AUC = ∫C dt

However wouldn't that mean - according to my understanding - that the product of this is the sum between the total conc of the drug and the time as the latter is a part of the calculation? And if it's the case, wouldn't that mean the AUC isn't just the total exposure?

Answer 1

The area under the curve (AUC) in a concentration vs. time graph represents the total drug exposure, incorporating both the extent and duration of presence in the body. It is a integrative measure, influenced by pharmacokinetic factors such as bioavailability and clearance, and is fundamental for assessing dosage and drug efficacy.

Step-by-step explanation:

The area under the curve (AUC) on a drug concentration vs. time graph represents total drug exposure over time. When we calculate the AUC, we are integrating the concentration of the drug in the bloodstream over a period.

This is not simply the sum of concentration and time but a cumulative measure that reflects both the extent and the duration of exposure after a drug dose. It's important to note that the AUC is a concept distinct from probability distribution functions such as cdf.

Factors like systemic clearance (CL), systemic bioavailability (F), and the drug's half-life (t₁2) all influence the shape of the curve and the resultant AUC, which in turn can be affected by variables such as drug-drug interactions (DDI) and the drug's volume of distribution (Vss).

Notably, the AUC can provide valuable information for determining the appropriate dosages, evaluating bioavailability/bioequivalence (BA/BE), and understanding the pharmacokinetics (ADME) of new chemical entities (NCES).