A 67-year-old man with an 18-year history of type 2 diabetes mellitus presents for a routine physical examination. His temperature is 36.9 C (98.5 F), his blood pressure is 158/98 mm Hg and his pulse is 82/minute and regular. On examination, the physician notes a non tender, pulsatile, mass in the mid-abdomen. A plain abdominal x-ray film with the patient in the lateral position reveals spotty calcification of a markedly dilated abdominal aoic walI. Following surgery, the patient is placed on a low-fat diet to reduce the risk of continued progression of his atherosclerotic disease. A bile acid sequestrant is added to interrupt enterohepatic circulation of bile acids. Which of the following agents was MOST likely prescribed?
A 67-year-old man with an 18-year history of type 2 diabetes mellitus presents for a routine physical examination. His temperature is 36.9 C (98.5 F), his blood pressure is 158/98 mm Hg and his pulse is 82/minute and regular. On examination, the physician notes a non tender, pulsatile, mass in the mid-abdomen. A plain abdominal x-ray film with the patient in the lateral position reveals spotty calcification of a markedly dilated abdominal aoic walI. Following surgery, the patient is placed on a low-fat diet to reduce the risk of continued progression of his atherosclerotic disease. A bile acid sequestrant is added to interrupt enterohepatic circulation of bile acids. Which of the following agents was MOST likely prescribed?
💡 Explanation
**Core Concept**
The patient is likely suffering from atherosclerotic disease, given the presence of a non-tender, pulsatile mass (abdominal aortic aneurysm) and a dilated abdominal aortic wall with spotty calcification. To reduce the risk of continued progression of atherosclerotic disease, a low-fat diet and a bile acid sequestrant are prescribed to interrupt the enterohepatic circulation of bile acids.
**Why the Correct Answer is Right**
Cholestyramine is a bile acid sequestrant that works by binding to bile acids in the intestine, preventing their reabsorption into the bloodstream and thus reducing the amount of cholesterol produced in the liver. This mechanism is particularly effective in reducing low-density lipoprotein (LDL) cholesterol levels, which are often elevated in patients with atherosclerotic disease. By interrupting the enterohepatic circulation of bile acids, Cholestyramine also reduces the amount of cholesterol available for absorption from the diet.
**Why Each Wrong Option is Incorrect**
* **Option A:** Atorvastatin is a statin, which works by inhibiting the enzyme HMG-CoA reductase in the liver, reducing cholesterol synthesis. While it is effective in reducing LDL cholesterol levels, it is not a bile acid sequestrant and does not target the enterohepatic circulation of bile acids.
* **Option C:** Clofibrate is a fibric acid derivative that works by activating peroxisome proliferator-activated receptor-alpha (PPAR-alpha), which increases the breakdown of triglycerides in the liver. However, it does not specifically target the enterohepatic circulation of bile acids and is not a bile acid sequestrant.
* **Option D:** Gemfibrozil is another fibric acid derivative that works similarly to clofibrate, activating PPAR-alpha to increase the breakdown of triglycerides in the liver. Like clofibrate, it does not specifically target the enterohepatic circulation of bile acids and is not a bile acid sequestrant.
**Clinical Pearl / High-Yield Fact**
Bile acid sequestrants like Cholestyramine can be effective in reducing LDL cholesterol levels, but they can also interfere with the absorption of fat-soluble vitamins (A, D, E, and K) and can cause gastrointestinal side effects such as constipation and bloating.
**✓ Correct Answer: B. Cholestyramine**
✓ Correct Answer: B. Cholestyramine
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