A 50-year-old female with hypothyroidism is prescribed levothyroxine. Levothyroxine works by:

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 hormones, leading to various symptoms. By prescribing levothyroxine, we are supplying the body with the thyroid hormone it lacks, thereby replacing the deficient hormone and restoring normal thyroid function. Explanation of other choices: A: Increasing the production of thyroid-stimulating hormone (TSH) is incorrect because levothyroxine does not directly affect TSH production. C: Inhibiting thyroid hormone synthesis is incorrect because levothyroxine does not inhibit thyroid hormone production. D: Increasing the metabolism of thyroid hormones is incorrect because levothyroxine does not directly increase the metabolism of existing thyroid hormones; it simply replaces the deficient hormone.

Correct Answer: A

Rationale: The correct answer is A: Blocking beta-1 adrenergic receptors in the heart. Bisoprolol is a beta-blocker that specifically targets beta-1 adrenergic receptors in the heart, leading to reduced heart rate and blood pressure. This helps in managing hypertension. Choices B, C, and D are incorrect because bisoprolol does not target beta-2 adrenergic receptors in the lungs, does not affect sodium excretion in the kidneys, and does not inhibit the conversion of angiotensin I to angiotensin II. The mechanism of action of bisoprolol primarily involves its selective blockade of beta-1 adrenergic receptors in the heart, making choice A the correct answer.

Correct Answer: B

Rationale: The correct answer is B: Epinephrine. Epinephrine is the first-line treatment for severe allergic reactions like anaphylaxis as it works quickly to reverse symptoms and prevent potentially life-threatening complications. It acts by constricting blood vessels, relaxing smooth muscles, and reducing swelling. Diphenhydramine (A) provides relief for mild allergic reactions but is not as fast-acting or potent as epinephrine. Loratadine (C) is an antihistamine that helps with allergy symptoms but is not suitable for treating anaphylaxis. Albuterol (D) is a bronchodilator used for respiratory conditions like asthma and would not be effective in treating anaphylaxis.

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: B

Rationale: The correct answer is B: Acetaminophen. Acetaminophen is commonly prescribed for managing chronic pain in osteoarthritis due to its analgesic properties. It is a non-opioid pain reliever with fewer side effects compared to opioids like morphine (A), which are typically reserved for severe pain. Methotrexate (C) is a disease-modifying anti-rheumatic drug used for rheumatoid arthritis, not osteoarthritis. Lisinopril (D) is an angiotensin-converting enzyme (ACE) inhibitor used for hypertension, not for pain management in osteoarthritis.