Operation requires and infusion of procainamide. It's 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 3mg/L. What is the probable steady state concentration after 2 days of infusion

Ref-Katzung 10/e p40,43,44 Half life of this drug is 2 hours and its plasma concentration is 3 mg/L 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 mg/L is 75% of steady state, it will amount to 4 mg/L.