Through the discussion above, hopefully you understand two different yet equal methods to consider the clearance of a drug from the bloodstream. OPTIONAL‐Please participate in the online discussion forum.
7.3 Clearance II Area under curve (AUC) video Please watch the online video (6 minutes 55 seconds). A condensed summary of this video can be found in the Video summary page. OPTIONAL‐Please participate in the online discussion forum.
Practicing AUC estimation Background: The two ways for calculating area under curve (AUC) of a Cp‐time plot are integration of the Cp‐time curve and using the trapezoid approximation. Both methods provide a value for determining AUC, which can then be used to calculate total clearance. Instructions: Read the passage below concerning the advantages and disadvantages of both methods. Use this information to answer the assessment questions below. Learning Goal: To understand both the different approaches for calculating AUC and how to use both methods. Integration Integration is an easy method for determining the AUC of a particular drug dose. Pharmacokinetic data, whether from animals or humans, are found in the form of Cp‐time data points. As we have seen in the assessment questions of Chapter 7.1, we can plot these points, especially in a linear ln Cp vs. time form, and quickly determine kel and the hypothetical Cpo. AUC is simply Cpo/kel.
Although integration is easy, it is not always accurate. The problem is that a series of ln Cp‐time data points can be forced to fit to a linear equation without the data actually being linear. If the data do not fit, then the simplicity of integration is of little gain because the AUC value will be inaccurate.