Posted by Angelman from IP 209.181.97.18 on July 29, 2007 at 21:58:06:
In Reply to: calculation posted by eddi on July 29, 2007 at 20:09:46:
First understand one vital point regarding solving such problems ie all units must be similar.It should not be one volume is in Liters and the other in ml or one time is in min and the other in hrs.
Coming to the question :
Clearance = 50ml/min = 3000 ml /hr = 3L/hr
Steady state plasma concentration = 20 mg/L
At a steady state plasma concentration
Rate of infusion = rate of elimination.
So if we are capable to calculate the rate of elimination then it will be rate of infusion .
We calculate as below :
Clearance = 50 ml/min = 3000 ml/hr = 3 L /hr
Css (steady state concentration ) = 20 mg/L
Clearance = Rate of elimination /Css =
Rate of elimination = Clearance x Css = 3 L /hr x 20 mg /L = 60mg /hr
After every eight hrs = 60 x 8 = 480 mg /8hr
If you have some different answer then let me know.
Best of luck.