Intially there is no drug in the body.
Once the iv infusion starts, the amount of drug in the body increases.
When drug elimination follows , the rate of drug elimination increases with time because the amount of the drug in the body is increasing.
Where k is the elimination rate constant and A is the amount of the drug in the body
The rate of drug elimination will keep increasing until it becomes equal to the rate of drug administration (rate of infusion) and the amount of the drug in the body will be constant, i.e. is achieved.
