At 12 hrs after IV administration of a bolus dose, the plasma level of a drug is 3 mg/L.If Vd = 10 L and the Elimination half life = 6 hrs, what was the dose administered?
A- 120 mg
B- 180 mg
C- 240 mg
D- 480 mg
E- 600 mg
A
now(after 2 half lives) we have 30 mg of drug in body(Vd * plasma concentration), so its first dose has been 120
AA
amount at the moment =3mg/Lx10L=30mg
initial amount =30x2x2=120mg
i dont get this one
can someone please explain? i've gotten it til 30mg but can't go on from there.
ok bro
what u get (30mg) is your current amount of drug
u administered ur drug 12 hour ago
after each 6 hours your drug amount drops in half
it means you have droped ur amound by half 2 times
or 6 hour ago u had 30x 2=60,12 hours ago u had 60 x 2=120mg
hope it helps
Half life given = 6 Hrs
We are looking at Drug plasma levels "After 12 Hrs"
(which is"TWO Half Lives, since t1/2 is 6 hr)
So At "2 Half lives" drug plasma concen. = 3 mg/L
and if we double this concen (3 mg) twice we'll have our "Plasma Conc at Zero time"
3----> 6-----> 12 mg (or u can do like this 3 * 2 * 2 = 12 mg/L)
so now we know the "Plasma Conc at Zero time" = 12 mg/ LITER
since the Vd = 10 LITER , we can use this formula for "Dose administered"
Dose = Cp * Vd
........= 12 * 10
........= 120 mg/L
that makes complete sense, thank you kocharov
once u get it, u can take the rout explained by kocharov777
Amount at the moment =3mg/Lx10L=30mg/L
Initial amount =30x2x2=120mg/L