# Area under the curve in a drug concentration curve

I am not from a background on pharamacokinetics and trying to learn some concepts.

I noticed that the definition for AUC involve the first 24 hours. For example in here AUC is defined as "the area under the concentration–time curve over 24 h divided by the MIC."

• Is there any reason why this 24 hours is selected?
• Say I test 2 treatment strategies. Strategy 1: 500 mg tablets given 3 times a day (500m g×3, 8 hours apart) and Strategy 2: 500 mg tablets given 3 times a day for 2 days (500 mg×6, 8 hours apart). In this case if I simulate the change in the drug concentration over time assuming exponential decay, then the two concentration curves would have the same values for the first 24 hours. Therefore the AUC obtained in the first 24 hours for these two strategies are the same. But strategy 2 performs better than strategy 1. So, in this case isn't the total area under the curve above MIC a better index than consdiering AUC in the first 24 hours?
• Is it wrong to inform why a particular dosing strategy is effective than the other one using 'Total area under the curve (rather than of the first 24 hours)'?
• The link in the question body isn't working, could you please correct it? Thanks. May 25, 2020 at 16:55

The usual definition does not involve the MIC or 24h: it is the area (~ integral) of the plasma concentration curve as a function of time, from first administration time $$t_0$$ time to infinity. (You will sometimes see it subscripted as $$\mathrm{AUC}_{0 \to \infty}$$)