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Old 01-15-2010
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Drug Ursodeoxycholic Acid

40y/o woman, discomfort in RUQ after eating. USS shows small cholesterol gallstones. She begins oral therapy with ursodeoxycholic acid. Which of the following is the best rationale for this treatment?

A) Addition of bilirubin to bile
B) Decreased concentration of bile acids
C) Decreased ratio of cholesterol to bile acids
D) Increased in the ability of the gallbladder to concentrate bile
E) increased in the concentration of lecithin in bile

Which is the answer, and why?
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Old 01-15-2010
joshi
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I think C
It's a bile acid sequestrant
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Old 01-15-2010
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The correct answer is D. Ursodeoxycholic acid is an option of treatment for cholesterol stones, with high failure and recurrence rate. Its main action is to "dissolve cholesterol stones" by increasing the concentration level of cholesterol at which saturation of bile with the latter occurs. In another wards it increases the ability of bile to dissolve cholesterol. If for example cholesterol precipitates on 100mg/dl, with ursodeoyxcholesterol it precipitates in 150mg/dl. Those numbers are just for clarification. It's also used in PBC and decreases disease progression, a commonly asked point in CK.

Ofcourse this choice and C are the only reasonable ones, other changes listed do not affect stone formtion or increase it.
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Old 01-15-2010
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I was thinking that bile acid sequestrants block the reabsorption of bile acids from the gut and thereby interrupting the enterohepatic circulation.
Therefore, the liver cell will direct it's cholestrol synthesis toward bile acids instead of acumilating in the lipoproteins and increased cellular synthesis also increases LDL receptor uptake.
Therefore choice C is the correct answer.

this is just my thinking may be drseddik is correct
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Old 01-16-2010
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Quote:
Originally Posted by leeman View Post
I was thinking that bile acid sequestrants block the reabsorption of bile acids from the gut and thereby interrupting the enterohepatic circulation.
Therefore, the liver cell will direct it's cholestrol synthesis toward bile acids instead of acumilating in the lipoproteins and increased cellular synthesis also increases LDL receptor uptake.
Therefore choice C is the correct answer.

this is just my thinking may be drseddik is correct
You are correct, but this is the mechanism of formation of gall stones (not treatment) in those taking bile acid sequestrants (also in crohn's disease), due to high (not low as the question says) cholesterol/bile acids. Ursodeoxycholic acid is not a bile acid sequestrant, it's a hydrophilic bile acid, it works by diffirent complicated mechanisms but the net effect is solubilization of stones (instead of cholecystectomy), not used for hyperlipidemias.
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Old 01-16-2010
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Quote:
Originally Posted by DrSeddik View Post
You are correct, but this is the mechanism of formation of gall stones (not treatment) in those taking bile acid sequestrants (also in crohn's disease), due to high (not low as the question says) cholesterol/bile acids. Ursodeoxycholic acid is not a bile acid sequestrant, it's a hydrophilic bile acid, it works by diffirent complicated mechanisms but the net effect is solubilization of stones (instead of cholecystectomy), not used for hyperlipidemias.
You are a star
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