Intermittent iv infusion

The drug is administered over a short period of time ( t' ) and the dose is repeated every one dosing interval (τ). The time between the maximum and the minimum concentrations is equal to (τ - t).

t '
τ
τ-t'

Following multiple drug administration the drug accumulates in the body until steady state is achieved. At steady state the maximum and the minimum plasma conc are constant.

Cpmin ss
Cpmax ss

Treating the short iv infusion as a bolus dose will result in overestimation of the maximum plasma conc and underestimation of the minimum plasma conc specially for drugs with short half lives.

iv bolus
Short iv infusion
Half life = 12 hr
There is no big difference in
the plasma profiles because
small amount of the drug is
eliminated during the infusion
period. This is because the
drug has long half life.
iv bolus
Short iv infusion
Half life = 1 hr
There is large difference
in the plasma profiles
because significant
amount of the drug is
eliminated during the
infusion period. This is
because the drug has
short half life.
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