Repetitive Intravenous Dosing

The series can be carried further for more doses:

CP2T = (CP1OR + CP1O)R

CP3O = (CP1OR + CP1O)R + CP1O

CP3T = [(CP1OR + CP1O)R + CP1O]R,...,etc.

The nth dosing interval has plasma concentrations at the beginning and end equalling:

Beginning = CP1O + CP1OR + CP1OR2 +...+CP1ORn-1

End = CP1OR + CP1OR2 + CP1OR3 +...+CP1ORn

R is always smaller than 1 and so Rn becomes smaller as n increases.  High power terms therefore become neglible as n increases.  Additional doses to the system will not change the value of CPnO or CPnT significantly and so is why the plasma concentrations reach a plateau instead of continuing to rise as more doses are given.  Hence, we define Cmax and Cmin as the plasma concentrations at the beginning and end, respectively, of the nth dosing interval after the plateau has been reached.  When n = infinity,