








USMLE Step 1 Forum USMLE Step 1 Discussion Forum: Let's talk about anything related to USMLE Step 1 exam 

Thread Tools  Search this Thread  Display Modes 
#1




Calculated the half life for this drug?
A new antiepileptic drug is being studied. The first test subject is determined to have a volume of distribution of 60 L for this drug and a renal clearance of 4 L/hour. What is the approximate half life of this drug in this patient?
A  2 hours B  7.5 hours C  10 hours D  15 hours E  18 hours 
#2




Cl = Vd x 0,67/half life
half life = Vd x 0.67/Cl = 60 x 0.67/4 = 10 hours The answer is : C
__________________
Time is immortal when you believe on something... 
#3




B , 7.5 hrs



#4




answer
Quote:

#5




Quote:
Hey, why do we need to divide the vd by 2? 
#6




C. 10 hours. The initial formula was correct.
T1/2 = 0.7 x Vd/Cl There's no need to divide by 2 ?!? 
#7




First we know that:
k = 0.693 / t 1/2 ==> t 1/2 = 0.693 / k and Clearence = V * k ==> k = Clearence / V then, t 1/2 = ( 0.693 * V ) / Clearence ==> 0.693 * 60 / 4 = 10 aprox. C  10 hours 
The above post was thanked by:  
aktorque (04012011) 
#8




Quote:

The above post was thanked by:  
bronchiole (04022011), harlesmd (04012011) 
Tags 
Pharmacology, Step1Questions 
Thread Tools  Search this Thread 
Display Modes  

Similar Threads  
Thread  Thread Starter  Forum  Replies  Last Post 
How USMLE Scores are calculated?  StepTaker  General Topics Recommended Threads  14  01252017 11:11 PM 
Halflife Calculation Question  good_boy_1234  USMLE Step 1 Forum  6  01072012 02:48 PM 
Pay half now, half later on your Step 2 CK Review Course!  DrInTraining  USMLE Step 2 CK Forum  1  02222011 04:39 AM 
Research Drug Half Life?  Yallah  USMLE Step 1 Forum  3  04192010 06:43 AM 
