Steady state is the time during which the concentration of the drug in the body stays consistent.the time to reach steady state is four to five half if the drug is given at regular intervals. The time to reach steady state is defined by the elimination half-life of the drug. After 1 half-life, you will have reached 50% of steady state. After 2 half-lives, you will have reached 75% of steady state, and after 3 half-lives you will have reached 87.5% of steady state. steady state is important for choosing the right dose and dosing interval to achieve a desired steady state concentration and for determining how long it will take for therapeutic exposures to be achieved during repeat or continuous dosing .