<prompt> A clinical pharmacologist is gathering pharmacokinetic data during clinical trials of a new antimicrobial agent. He has already determined that the half-life of this drug is 4 hours. He began a continuous intravenous drip 24 hours ago at a rate of 10 mgmin. Blood tests after 24 hours reveal that the patients drug plasma concentration is 20 mgL. What is the clearance of this agent?0.5 Lmin2 Lmin10 Lmin50 Lmin  <response>: You must be familiar with the maintenance dose equation, to answer this question: M.D. Cl x CpssF, where M.D. maintenance dose Cl clearance Cpss plasma concentration at steady state F bioavailability In this case, M.D. is 10 mgmin; F, or how much drug is absorbed, is 1 100 because drugs administered I.V. are completely absorbed. F becomes impoant when drugs are given orally. Cpss 20 mgL; it takes 4 -5 half-lives to achieve steady state, so this drug has been administered for a time period equaling 6 half-lives. Solving, 10 mgmL Cl x 20 mgmL Cl 0.5 Lmin 