Steady state concentration of a drug is achieved in: September 2007

Ans. C: 4-5 Half Lives When a drug is infused IV, the plasma concentration continues to rise until elimination equals the rate of delivery into the body. Regardless of the drug, 50% of the plateau concentration is attained in 1 half-life of the drug; for 2, 3, and 4 half-lives, 75%, 87.5%, and 93.75% of the plateau concentration are reached, respectively. For practical purposes, steady state is achieved by 4-5 half-lives.