<prompt> Operation requires and infusion of procainamide. Its half life is 2hrs. The in fusion is begin at 9:00 a.m. to 1:00 p.m. on the same day, the blood concentration is found to be 3mgL. What is the probable steady state concentration after 2 days of infusion3mgL4mgL6mgL15mgL  <response>: Ref-Katzung 10e p40,43,44 Half life of this drug is 2 hours and its plasma concentration is 3 mgL after 4 hours 9AM to 1 PM. This means, after 2 half lives 4 hours plasma concentration is 3mg L. We know, by constant i.v. infusion, plasma concentration attained is 75 of the steady state in 2 half lives. So, if 3 mgL is 75 of steady state, it will amount to 4 mgL. 