Two-compartment catenary model for extravascular administration with incomplete absorption

3 Two-compartment catenary model for extravascular administration with incomplete absorption 

The effect of incomplete absorption is that only a fraction of a single-dose D is made available to the central plasma compartment. The solution of the previous model needs, therefore, to be modified by replacing the term D by F D. Consequently the area under the curve AUCg under incomplete extravascular absorption will be smaller than the maximal AUC that results from complete absorption. The latter, as we have seen is equal to the AUC obtained from a single intravenous injection, which we denote by AUC,. These considerations can be summarized as follows  

If an oral or parenteral plasma concentration curve is available together with an intravenous one from the same subject(s), then one can derive the absorption fraction from these. 

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