A 55-year-old male with diabetes is prescribed dapagliflozin. Dapagliflozin works by:

Correct Answer: A

Rationale: The correct answer is A: Inhibiting the reabsorption of glucose in the kidneys. Dapagliflozin is a sodium-glucose co-transporter 2 (SGLT2) inhibitor, which prevents the reabsorption of glucose in the kidneys, leading to increased glucose excretion in the urine. This mechanism helps lower blood sugar levels in patients with diabetes. Choices B, C, and D are incorrect because dapagliflozin does not directly impact insulin sensitivity, insulin secretion, or incretin hormone breakdown. It primarily acts on the kidneys to reduce blood glucose levels.

Correct Answer: A

Rationale: The correct answer is A: Inhibiting sodium reabsorption in the kidneys. Chlorthalidone is a thiazide diuretic that works by acting on the distal convoluted tubule of the kidneys to inhibit sodium reabsorption. This leads to increased excretion of sodium and water, resulting in decreased blood volume and reduced blood pressure. Blocking calcium channels (B) is the mechanism of action for calcium channel blockers, not thiazide diuretics. Thiazide diuretics do not directly inhibit the action of aldosterone (C), which is a hormone that regulates sodium and potassium balance. Thiazides can cause potassium loss, but they do not directly increase the excretion of potassium (D).

Correct Answer: A

Rationale: The correct answer is A: Ondansetron. Ondansetron is a commonly used antiemetic medication that works by blocking serotonin receptors in the brain, thus preventing nausea and vomiting. It is specifically indicated for the prevention of chemotherapy-induced nausea and vomiting. Loperamide (B) is an antidiarrheal medication, Omeprazole (C) is a proton pump inhibitor used for acid reflux, and Dexamethasone (D) is a corticosteroid used for inflammation and immune suppression. These medications are not typically used for preventing nausea and vomiting in chemotherapy patients.

Correct Answer: A

Rationale: The correct answer is A: Blocking beta-1 adrenergic receptors in the heart. Atenolol is a beta-blocker that primarily acts on beta-1 receptors in the heart, reducing heart rate and blood pressure. This helps in managing hypertension. Beta-2 receptors are predominantly found in the lungs, so choice B is incorrect. Choice C refers to calcium channel blockers, not atenolol. Choice D is related to diuretics, not beta-blockers like atenolol. Thus, the correct answer is A due to atenolol's specific action on beta-1 receptors in the heart.

Correct Answer: A

Rationale: The correct answer is A because sitagliptin works by inhibiting the enzyme dipeptidyl peptidase-4 (DPP-4), which breaks down incretin hormones like GLP-1 and GIP. By inhibiting DPP-4, sitagliptin prolongs the action of these hormones, leading to increased insulin release and decreased glucagon secretion, ultimately lowering blood glucose levels. Choices B, C, and D are incorrect because sitagliptin does not directly increase insulin secretion from the pancreas, inhibit glucose absorption in the intestines, or increase renal glucose excretion.