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Old 07-31-2011
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I agree drug distribution

A dose of 90mg of drug X is administered to a 50kg woman. The plasma concentration of the drug prior to metabolism or excretion is found to be 9mg/L. From the apparent volume of distribution, you can assume that drug X appears to be:
A. Confined to tissues
B. Confined to plasma
C. Confined to extracellular fluid
D. Highly plasma protein bound
E. Distributed in total body water
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Old 07-31-2011
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Quote:
Originally Posted by ricko335 View Post
A dose of 90mg of drug X is administered to a 50kg woman. The plasma concentration of the drug prior to metabolism or excretion is found to be 9mg/L. From the apparent volume of distribution, you can assume that drug X appears to be:
A. Confined to tissues
B. Confined to plasma
C. Confined to extracellular fluid
D. Highly plasma protein bound
E. Distributed in total body water
the ans is E
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Old 07-31-2011
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E high tissue distribution ..for e.g anesthetic has high tissue distrubution and drugs with high tissue distribution can b redistributed back to blood increasing blood levels later on as there complications
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Old 07-31-2011
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answer C. confined to extracelluar space (interstitial and blood)
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Old 07-31-2011
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VD= Dose/plasma conc.
=90 mg/ 10 mg/L
= 9 L

A. Confined to tissues - VD would be high about 30L
B. Confined to plasma - VD would be less about 5-6 L
C. Confined to extracellular fluid
D. Highly plasma protein bound- Same as B
E. Distributed in total body water- Same as A
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Old 08-01-2011
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Ans C Vd = 9L there fore confined to ecf only
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Old 08-01-2011
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C - ECF only - Vd = 10 Liter == 1/3 total body water
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Old 08-01-2011
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Correct Answer answer

the correct answer is extracellular fluid

Volume of distribution = dose injected IV / concentration in plasma during equilibrium
= 90mg / 9mg/L
= 10 Liters

10 Liters is roughly 20% weight of a 50kg woman (10/50 = 0.2). Remember, 40% of total body weight = intracellular, and 20% of total body weight = extracellular.
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