Figure 14.5.1 Drug Concentration after Multiple Doses Showing Accumulation
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Figure 14.5.1 Drug Concentration after Multiple Doses Showing Accumulation
Concentration at the end of the first dosing interval
Equation 14.5.1 Cp after the First Dose
where 
This gives the plasma concentrations at the end of first interval, where τ is the dosing interval in hours.
Concentration at the start of the second interval
Equation 14.5.2 Cp at the Start of the Second Interval
Concentration at the end of the second dose interval
Equation 14.5.3 Cp at the End of the Second Interval
and so on.
It will help if we define the parameter, R = e-kel • τ, which is the fraction of the initial plasma concentration remaining at the end of the dosing interval.
Then
Equation 14.5.4 Cp at the End of the Second Interval
Equation 14.5.5 Cp at the Start of the Third Interval
this is a geometric series with each term R times the preceding term.
Equation 14.5.6 Cp at the Start of the nth Interval
Equation 14.5.7 Cp at the End of the nth Interval
these two sums are sums of geometric series and they can be simplified to give
Equation 14.5.8 Cp at the Start of the nth Interval
Equation 14.5.9 Cp at the End of the nth Interval
Starting with the first equation (Equation 14.5.8) we can calculate drug concentration in blood or plasma at any time following uniform multiple IV bolus administration.
Equation 14.5.10 Cp at time,t, after the nth IV Bolus Dose
where here t = time since the last dose.
Equation 14.5.11 Cp at time, t, after the nth IV Bolus Dose
General Equation
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