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#1
08-10-2012
 USMLE Forums Master Steps History: 1+CK+CS+3 Posts: 1,186 Threads: 119 Thanked 815 Times in 434 Posts Reputation: 825
Calculate the Drug Half Life?

a 70 yr old man is treated with a new antifungal drug for fungal sepsis..the drug is actively secreted by kidney and has volume of distribution of 35 litres and clearance of 690ml/min...the half life of drug(in min) is closest to which of the following..?
a) 15
b) 35
c) 65
d) 105
e) 125

when i calculated i got 35 as an answer..but when i refer the key it gave as 15...please explain..?.. thank you

#2
08-10-2012
 USMLE Forums Scout Steps History: Step 1 Only Posts: 41 Threads: 1 Thanked 53 Times in 34 Posts Reputation: 63

If you got that answer from the nbme 6 the right answer is 35 not 15.
t 1/2 = 0.7 x vd/ cl
35=0.7x 35000ml/690 ml/min

the only change you should do is the liters of vd to ml
 The above post was thanked by: Doc4Step1 (08-10-2012), meanmr.mustard (08-10-2012), venky2600 (08-10-2012)

 Tags Pharmacology-, Step-1-Questions

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