Elimination rate constant
From Wikipedia, the free encyclopedia
The elimination rate constant K or Ke is a value used in pharmacokinetics to describe the rate at which a drug is removed from the human system.[1]
It is often abbreviated K or Ke. It is equivalent to the fraction of a substance that is removed per unit time measured at any particular instant and has units of T−1. This can be expressed mathematically with the differential equation
,
where is the blood plasma concentration of drug in the system at a given point in time
,
is an infinitely small change in time, and
is the concentration of drug in the system after the infinitely small change in time.
The solution of this differential equation is useful in calculating the concentration after the administration of a single dose of drug via IV bolus injection:
- Ct is concentration after time t
- C0 is the initial concentration (t=0)
- K is the elimination rate constant