With IV infusion, a drug reaches 90% of its final steady state in 10 hours. The elimination half-life of the drug must be approximately

Time to reach 90% of final steady-state plasma levels is given by: 3.3xhalflife.Because it takes 10 h to reach 90% steady state, thenHalflife=3.310 =3hTo achieve "clinical" steady state usually takes approximately 5xhalflife.