**Concentration at the end of the first dosing interval**

**Equation XIV-11 Cp after the First Dose**

where

This gives the plasma concentrations at the end of first interval, where t is the dosing interval in hours.

At the start of the second interval

then at the end of the second dose interval

and so on.

It will help if we define the parameter

which is the fraction of the initial plasma concentration remaining at the end of the dosing interval.

Then

this is a geometric series with each term R times the preceding term.

**Start**

**Equation XIV-12 Cp Immediately after the nth Doses**

**End**

**Equation XIV-13 Cp at the end of nth Dosing Interval**

these two sums can be simplified to give

**Start**

**Equation XIV-14 Cp at the Beginning on the nth Dosing Interval**

and

**End**

**Equation XIV-15 Cp at the End of the nth Dosing Interval**

using the first equation (Equation XIV-14) we can calculate the concentration in plasma at any time following uniform multiple IV bolus administration.

where t = time since the last dose. Then

**Equation XIV-16 Cp at any Time after n Doses**

**GENERAL EQUATION**

This page was last modified: 12 February 2001

Copyright 2001 David W.A. Bourne