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

#1
10-12-2015
 USMLE Forums Newbie Steps History: Not yet Posts: 1 Threads: 1 Thanked 0 Times in 0 Posts Reputation: 10

The data given in the following table are the plasma concentrations of Topamax as a function of time after i.v. administration of 50mg Topamax to a subject.
Time (hr) Cp (mg/L)
0.25 ------------ 200
0.5 ------------- 100
0.75 ------------- 50
1.0 -------------- 25
1.25------------- 13.5
1.5 ------------ 7
1.75 ------------- 3.5

So basically if at Co (initial plasma conc) you'd have a drug plasma concentration of around 400mg (since half life is 0.25hrs). Now to me this makes no sense. How can you get such a high concentration of topmax in the blood with only 50mg administered in the first place?

Is it a typo or am I missing something?

#2
10-13-2015
 USMLE Forums Newbie Steps History: Not yet Posts: 8 Threads: 3 Thanked 2 Times in 2 Posts Reputation: 12

I would say that there is a typo error
#3
10-13-2015
 USMLE Forums Addict Steps History: 1 + CS Posts: 161 Threads: 18 Thanked 97 Times in 53 Posts Reputation: 107

If the plasma volume is 125ml then its definitely possible

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