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#1
10-13-2011
 USMLE Forums Guru Steps History: Step 1 Only Posts: 343 Threads: 127 Thanked 525 Times in 192 Posts Reputation: 535
Calculating the drug plasma level

A drug achieves a plasma level of 16mg/L shortly after administration of first oral dose. If half life and dosing intervals are both 6hrs what is approx plasma level before administration of 5th oral dose?

a) 30mg/L
b) 15mg/L
c) 31mg/L
d) 24mg/L
e) 28mg/L
 The above post was thanked by: drfchakera (10-15-2011), roodiemd (10-14-2011), zainsyed (05-01-2014)

#2
10-13-2011
 USMLE Forums Guru Steps History: Step 1 Only Posts: 326 Threads: 20 Thanked 220 Times in 124 Posts Reputation: 232

b) 15 mg/l
#3
10-13-2011
 USMLE Forums Addict Steps History: Step 1 Only Posts: 145 Threads: 8 Thanked 76 Times in 57 Posts Reputation: 86

c)31mg/L

1st hr 8(t1/2 of 16) + 16(dose) = 24

2nd hr 12(t1/2 of 24) + 16(dose) = 28

3rd hr 14(t1/2 of 28) + 16(dose) = 30

4th hr 15(t1/2 of 30) + 16(dose) = 31 --> Before 5th dose.

5th...
 The above post was thanked by: roodiemd (10-14-2011), strive (1 Week Ago)

#4
10-14-2011
 USMLE Forums Guru Steps History: Step 1 Only Posts: 343 Threads: 127 Thanked 525 Times in 192 Posts Reputation: 535

 The above post was thanked by: jahn77 (10-14-2011)
#5
10-14-2011
 USMLE Forums Addict Steps History: Step 1 Only Posts: 145 Threads: 8 Thanked 76 Times in 57 Posts Reputation: 86

Quote:
 Originally Posted by INCOGNITO correct answer is 15mg/L
I think I read the question wrong way. Anyway can you please explain it for me??
#6
10-14-2011
 USMLE Forums Guru Steps History: Step 1 Only Posts: 343 Threads: 127 Thanked 525 Times in 192 Posts Reputation: 535

question says JUST BEFORE 5th dose is given so bottom WHERE ARROW IS GIVEN its 15 mg/L

pardon for low quality pic..

click image to enlarge
 The above post was thanked by: Amenah (10-14-2011), Cairo (10-15-2011), Dhakshi (01-04-2017), whocares13 (10-14-2011)

 Tags Figures-, Pharmacology-, Step-1-Questions

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