Bioavailability and Bioequivalence

Now let’s try to use the equation to calculate the bioavailability of a penicillin given as IV versus given as a tablet. Let’s say that the AUC of 25 mg penicillin after administered as IV is 100 mg.h/L and that the AUC is 60 mg.h/L after giving a tablet containing 100 mg penicillin. What then is the absolute bioavailability of the penicillin?

The values given in Example 2 are inserted into the equation:

Thus, the absolute bioavailability of such a tablet is 15%.

As seen in Figures 1 and 2, the concentration – time profiles differ for the tablet and IV injection (the two formulations). And it is even more complicated than this. The profile obtained between them would likely differ to some extent if you made a similar profile for the two formulations using ’Matt’ and ‘Per’ as test persons. This is because bioavailability is affected by a number of parameters within individuals.