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jvvora
06-19-2008, 02:19 PM
An antibiotic is given by IV push at 100mg/day.
Half life is 36hrs.
Volume of distribution is 10 liters.

1) 150mg
2) 215mg
3) 310mg
4) 375mg
5) 475mg.

OzPharmacist
06-19-2008, 04:57 PM
Hi jvvora

The answer I think is 2) 215mg

t 1/2 = 0.693/K so K = 0.01925
Ri = Css x Vd x K so Css = 100mg/24hr / 10L x 0.019 = 21.93 mg/L
Ld = Css x Vd so Ld = 219mg

Anyone else get the same answer?

vivyzeta
06-20-2008, 01:56 AM
Yes. I got 216 mg.

Css=R/VdxK => 100mg/24h/10Lx0.01925 (from t1/2)= 21.6 mg

CSSxVd=216 mg

jvvora
06-20-2008, 10:09 PM

All the best.

starzs9
06-21-2008, 04:02 AM
Hi Vora,
I just think this is correct but...correct me if iam wrong please.
First find the Css
Css=R/Vd*K
100/10*0.693/36*60(36 hours+36*60)
Css=312
Then,

starzs9
06-21-2008, 04:08 AM
not so sure

vivyzeta
06-21-2008, 03:38 PM
Hi Starzs can you please explain? where did you get 60 from?
thanks,

Vivi

starzs9
06-21-2008, 04:16 PM
not so sure

janis70
06-22-2008, 09:17 PM
Hi Starz9,
The IV push value is 100mg/day so you can convert everything to hours.
The half life is already in hours (36 hours)
resolving the problem you can use 100mg/24 hs=4,167mg/hs and leave t1/2 in hours, don't convert it to minutes.
K=0,693/36=0,01925 hours-1
Css=R/VdxK => 100mg/24h/10Lx0.01925 (from t1/2)= 21.6 mg

CSSxVd=216 mg