If a patient was given 1000 mg of a drug {1st order kinetics} initially and after 2 hours the drug level in plasma is 500 mg, after 8 hours what will be the level in plasma?

(B) 62.5> If we measure the slope of this curve at a number of times we are actually measuring the rate of change of concentration at each time point, ACp/A, represented by the straight line tangents in Figure.# First order kinetics: Constant Fraction of drug is eliminated at constant interval of time i.e.., 50% of drug is eliminated at every t1/2.> Rate of elimination is directly proportional to drug administered.> In this case the drug is following first order kinetics, drug administered is 1000 mg, t1/2 is 120 min.> So, 1000 mg - 500 mg (in 2hrs) - 250 mg (in 2hrs) -125 mg (in 2hrs).> Totally after 8 hours the drug remained is 62.5 mg