s say the half life of Drug A is 5 hours and you have taken 10mg dose.
In the next 5 hours, only 5mg of the drug will remain
in the body.
In another 5 hours only 2.5mg will remain and then 1.25mg and so on.
It takes about 4 -5 half lives for the drug to be completely metabolized. Hence in the case of Depakote, since the half life is 16 ± 3 hours (lets take a maximum of 19 hours), the time for complete metabolism will be 19 X 5 = 95 hours. That means 4 complete days.