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Plasma Drug Concentration During a Continuous Infusion

Description

When a constant infusion of a drug is given, the plasma drug concentration will rise as a continuous curve, rapidly at first but then more slowly, until it reaches a plateau at steady state. The time to the steady state level depends on the number of drug half-lives since the infusion was started.


 

Parameters:

(1) concentration of the drug at steady state

(2) target concentration of the drug during the rise to steady state

 

number of drug half-lives required to reach a target drug concentration in plasma =

= (-1.44) * LN(((concentration at steady state) - (target drug concentration)) / (concentration at steady state))

= (-1.44) * LN(1 - (decimal fraction of steady state reached so far))

 

The time to steady state can be shortened by giving a bolus infusion (see below).

 


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Specialty

ICD-10