A 60-year-old female with diabetes is prescribed metformin. Metformin works by:

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: 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.

Correct Answer: B

Rationale: The correct answer is B: Inhibiting HMG-CoA reductase in the liver. Rosuvastatin is a statin medication that works by inhibiting the enzyme HMG-CoA reductase, which plays a key role in the liver's production of cholesterol. By inhibiting this enzyme, rosuvastatin reduces the synthesis of cholesterol in the liver, leading to decreased levels of LDL cholesterol in the bloodstream. This mechanism helps lower the risk of cardiovascular events in patients with hyperlipidemia. Choice A is incorrect because rosuvastatin does not directly inhibit the absorption of cholesterol in the intestines. Choice C is incorrect as rosuvastatin primarily lowers LDL cholesterol levels and has minimal impact on increasing HDL cholesterol levels. Choice D is incorrect as rosuvastatin does not directly increase the excretion of cholesterol in the bile.

Correct Answer: D

Rationale: The correct answer is D, "All of the above." Atorvastatin, simvastatin, and lovastatin are all statin medications that lower cholesterol by inhibiting the HMG-CoA reductase enzyme. This enzyme is crucial in the production of cholesterol in the liver. By inhibiting this enzyme, statins help reduce the amount of cholesterol synthesized in the body, leading to lower overall cholesterol levels. Therefore, all three medications listed are effective in lowering cholesterol levels. The other choices (A, B, C) are incorrect as they do not fully address the question and fail to acknowledge that all three medications listed are part of the same drug class with the same mechanism of action.

Correct Answer: B

Rationale: The correct answer is B because celecoxib selectively inhibits COX-2 enzymes, which are responsible for producing prostaglandins involved in pain and inflammation. By targeting COX-2 specifically, celecoxib reduces pain and inflammation without affecting COX-1, which is important for maintaining gastrointestinal mucosa and platelet function. Therefore, choice A is incorrect as celecoxib does not inhibit both COX-1 and COX-2. Choices C and D are also incorrect as celecoxib does not increase prostaglandin synthesis or bind to opioid receptors.