Which of the following skin structures was most likely the site of action of the prescribed drug?

Correct Answer: C

Rationale: The correct answer is C: Stratum corneum. The drug most likely acted on the outermost layer of the skin, the stratum corneum, as it is responsible for drug absorption and penetration. The other layers (A, B, D) are deeper layers of the skin and are not primarily involved in drug action. The stratum basale (A) is the innermost layer responsible for cell division, the stratum spinosum (B) provides strength and flexibility, and the pigment layer (D) contains melanocytes responsible for skin color. Therefore, the stratum corneum is the most likely site for drug action due to its role in drug absorption and penetration.

Correct Answer: B

Rationale: The correct answer is B: Activating peroxisome proliferator-activated receptor alpha (PPAR-alpha). Fenofibrate is a fibrate medication that works by activating PPAR-alpha receptors. PPAR-alpha activation leads to increased expression of genes involved in lipid metabolism, resulting in decreased triglyceride levels and increased HDL cholesterol levels. This mechanism of action is specific to fenofibrate and other fibrates. Now, let's analyze why the other choices are incorrect: A: Inhibiting HMG-CoA reductase in the liver - This is the mechanism of action of statins, not fibrates like fenofibrate. C: Blocking calcium channels in the blood vessels - This is unrelated to the mechanism of action of fenofibrate and is more commonly associated with calcium channel blockers used in hypertension management. D: Increasing the absorption of cholesterol in the intestines - This is the mechanism of action of bile acid sequestrants, not fibrates like fenofibrate

Correct Answer: B

Rationale: The correct answer is B: Improving insulin sensitivity in peripheral tissues. Metformin works by decreasing insulin resistance in peripheral tissues, making them more responsive to insulin. This helps to lower blood glucose levels by improving glucose uptake and utilization. Choice A is incorrect because metformin does not directly increase insulin secretion from the pancreas. Choice C is incorrect as metformin does not inhibit glucose absorption in the intestines. Choice D is incorrect as metformin primarily reduces blood glucose levels by improving insulin sensitivity rather than increasing renal glucose excretion.

Correct Answer: A

Rationale: The correct answer is A: Hair loss. Chemotherapy drugs target fast-growing cells, including hair follicles, leading to hair loss. This is a well-known side effect of chemotherapy. Increased appetite (B) is not a common side effect; in fact, many patients experience loss of appetite. Dehydration (C) can occur due to other reasons like nausea and vomiting, not directly from chemotherapy. Drowsiness (D) is more associated with certain medications or the cancer itself, not a direct side effect of chemotherapy.

Correct Answer: A

Rationale: The correct answer is A: Levothyroxine. Levothyroxine is a synthetic form of the thyroid hormone T4, used to treat hypothyroidism by supplementing the deficient thyroid hormone levels in the body. It helps regulate metabolism, energy levels, and overall bodily functions. Methimazole (B) is used to treat hyperthyroidism by reducing the production of thyroid hormones. Fluoxetine (C) is an antidepressant, not used for thyroid conditions. Lithium (D) is used for bipolar disorder, not for hypothyroidism. In summary, Levothyroxine is the correct choice as it directly replaces the deficient thyroid hormone, while the other options are not indicated for treating hypothyroidism.