Radioiodines (I131 and I132) is suitable for:

Correct Answer: A

Rationale: The correct answer is A: Elderly patients (over 45 years). Radioiodines are suitable for elderly patients due to their slower metabolism, which allows for better uptake and retention of the radioiodine in the thyroid gland. This results in more effective treatment of conditions like hyperthyroidism or thyroid cancer. Pregnant women, nursing mothers, and younger patients should avoid radioiodine therapy due to potential risks to the fetus, infant, and developing thyroid gland, respectively. Overall, the slower metabolism in elderly patients makes them the most suitable candidates for radioiodine therapy.

Correct Answer: B

Rationale: The correct answer is B because H2 histamine receptor subtype is mainly distributed in gastric mucosa, cardiac muscle, mast cells, and brain. This receptor subtype plays a crucial role in gastric acid secretion and cardiovascular functions. Choice A is incorrect because smooth muscle and endothelium are primarily associated with H1 receptors, not H2 receptors. Choice C is incorrect because presynaptic H3 receptors are found in the brain and other neurons, not H2 receptors. Choice D is incorrect because H2 receptors are not distributed in smooth muscle, endothelium, or presynaptic regions as mentioned in choices A and C.

Correct Answer: B

Rationale: The correct answer is B: Tocopherol. Tocopherol is a fat-soluble vitamin, specifically referring to Vitamin E. Fat-soluble vitamins dissolve in fat and are stored in the body's fatty tissues, allowing for longer-term storage compared to water-soluble vitamins. Ascorbic acid (A) is Vitamin C, which is water-soluble. Thiamine (C) and Riboflavin (D) are both water-soluble B vitamins. Therefore, the correct choice is B because it is the only fat-soluble vitamin among the options provided.

Correct Answer: C

Rationale: The correct answer is C: L-asparaginase. This enzyme is used in cancer therapy to treat certain types of leukemia by depleting asparagine, an essential amino acid for cancer cell growth. Pepsin (A) is a digestive enzyme, urokinase (B) is involved in fibrinolysis, and lysozyme (D) is an antimicrobial enzyme, none of which are used in cancer therapy.

Correct Answer: B

Rationale: The correct answer is B: Lovastatin (Mevacor). Lovastatin is a statin medication used to lower cholesterol levels. It can cause muscle damage, particularly when used in combination with drugs like erythromycin, which can increase lovastatin levels in the body, leading to an increased risk of muscle-related side effects. Cholestyramine (A) is a bile acid sequestrant used to lower cholesterol, but it does not cause muscle damage. Gemfibrozil (C) and Probucol (D) are also cholesterol-lowering drugs, but they are not known to cause significant muscle damage, especially when combined with erythromycin.