A 65-year-old female with chronic atrial fibrillation is prescribed apixaban. Apixaban works by:

Correct Answer: B

Rationale: The correct answer is B: Inhibiting factor Xa. Apixaban is a factor Xa inhibitor, which prevents the formation of thrombin. Factor Xa is a key enzyme in the coagulation cascade that converts prothrombin to thrombin. By inhibiting factor Xa, apixaban effectively reduces blood clot formation. Thrombin is directly inhibited by other anticoagulants like dabigatran. Vitamin K antagonists (e.g. warfarin) block the action of vitamin K, and antiplatelet agents (e.g. aspirin) inhibit platelet aggregation but do not work by inhibiting factor Xa like apixaban.

Correct Answer: A

Rationale: Rationale: Lisinopril is an ACE inhibitor that blocks the conversion of angiotensin I to angiotensin II, leading to vasodilation and decreased blood pressure. Losartan is an angiotensin II receptor blocker, not an ACE inhibitor like Lisinopril. Hydrochlorothiazide is a diuretic that acts on the kidneys, not on the renin-angiotensin system. Amlodipine is a calcium channel blocker that works by relaxing blood vessels, not by inhibiting the angiotensin-converting enzyme. Therefore, Lisinopril is the correct choice for treating hypertension by inhibiting the enzyme that converts angiotensin I to angiotensin II.

Correct Answer: A

Rationale: The correct answer is A: Inhibiting osteoclast-mediated bone resorption. Alendronate is a bisphosphonate drug that works by inhibiting osteoclasts, which are responsible for breaking down bone tissue. By inhibiting osteoclast activity, alendronate helps to reduce bone resorption and increase bone density. This is particularly beneficial for patients with osteoporosis, as it helps to slow down bone loss and reduce the risk of fractures. Choice B is incorrect because alendronate does not directly affect calcium absorption from the intestine. Choice C is incorrect because alendronate does not promote osteoblast activity, which is responsible for building new bone tissue. Choice D is incorrect because alendronate does not increase parathyroid hormone levels; in fact, it can actually decrease parathyroid hormone levels by affecting calcium homeostasis.

Correct Answer: B

Rationale: The correct answer is B: Replacing deficient thyroid hormone. Levothyroxine is a synthetic form of the thyroid hormone thyroxine (T4). In hypothyroidism, the thyroid gland does not produce enough thyroid hormone, leading to symptoms such as fatigue and weight gain. By prescribing levothyroxine, the deficient thyroid hormone levels can be restored to normal, alleviating the symptoms of hypothyroidism. Explanation for why the other choices are incorrect: A: Increasing the production of thyroid-stimulating hormone (TSH) - Levothyroxine does not directly affect TSH production; TSH is secreted by the pituitary gland to stimulate the thyroid gland. C: Inhibiting thyroid hormone synthesis - Levothyroxine does not inhibit thyroid hormone synthesis; it provides the body with the thyroid hormone it lacks. D: Increasing the metabolism of thyroid hormones - Levothyroxine does not increase the metabolism of thyroid hormones; it directly

Correct Answer: B

Rationale: The correct answer is B: Lithium. Lithium is used to treat bipolar disorder by stabilizing mood. It helps to reduce the frequency and severity of manic episodes. Carbamazepine (A) is also used to treat bipolar disorder, but it primarily targets manic episodes. Sertraline (C) is an antidepressant used to treat depression and anxiety disorders, not bipolar disorder. Lorazepam (D) is a benzodiazepine used to treat anxiety and insomnia, not bipolar disorder. In summary, Lithium is the correct choice as it specifically targets mood stabilization in bipolar disorder.