These agents must be given parenterally because they are not absorbed when given orally:

Correct Answer: A

Rationale: The correct answer is A: Osmotic diuretics. These agents are not absorbed when given orally due to their large molecular size, which prevents them from passing through the gastrointestinal mucosa. They must be administered parenterally for effective absorption and distribution in the body to exert their diuretic effects. Loop diuretics (B) are well-absorbed orally in the gastrointestinal tract. Thiazide diuretics (C) are also absorbed when given orally and act primarily in the distal convoluted tubule. Potassium-sparing diuretics (D) can be absorbed orally and exert their effects in the collecting duct of the nephron.

Correct Answer: C

Rationale: The correct answer is C because fluoroquinolones are effective in treating both urinary tract and respiratory tract infections caused by bacteria, as well as bacterial diarrhea. They have broad-spectrum activity against various bacteria commonly involved in these infections. Choice A is incorrect because fluoroquinolones are not typically recommended as a first-line treatment for urinary tract infections. Choice B is incorrect because fluoroquinolones are not commonly used to treat bacterial diarrhea. Choice D is incorrect because while fluoroquinolones can be used for respiratory tract infections, it is not their primary indication.

Correct Answer: B

Rationale: Step 1: Zidovudine is an antiretroviral medication used to treat HIV. Step 2: Anemia and neutropenia are common unwanted effects of zidovudine due to bone marrow suppression. Step 3: Nausea and insomnia are also common side effects of zidovudine. Step 4: Hallucinations, dizziness, hypertension, vomiting, and peripheral neuropathy are not typically associated with zidovudine. Step 5: Therefore, the correct answer is B as it accurately lists unwanted effects of zidovudine based on its pharmacological profile.

Correct Answer: A

Rationale: The correct answer is A because milrinone is a positive inotrope that can be used as an alternative to digoxin for heart failure. Discontinuing digoxin is appropriate if the patient is experiencing toxicity symptoms. Starting milrinone provides the necessary positive inotropic support without the risk of digoxin toxicity. Option B is incorrect because physostigmine is used for anticholinergic toxicity, not digoxin toxicity. Decreasing the digoxin dose alone may not be sufficient to address toxicity symptoms. Option C is incorrect because atropine is used for bradycardia and not for digoxin toxicity. Decreasing the digoxin dose alone may not be sufficient to address toxicity symptoms. Option D is incorrect because metoprolol is a beta-blocker and can worsen symptoms of digoxin toxicity by further slowing the heart rate. Discontinuing digoxin is appropriate, but starting metoprolol is not recommended.

Correct Answer: D

Rationale: The correct answer is D: Amiodarone. Amiodarone is a class III antiarrhythmic drug commonly used to prevent further fibrillatory episodes, particularly in patients with atrial fibrillation. It has a broad spectrum of antiarrhythmic effects and is effective in controlling various types of arrhythmias. Mexiletine (A) is a class IB antiarrhythmic drug used for ventricular arrhythmias. Sotalol (B) is a non-selective beta-blocker with class III antiarrhythmic properties. Quinidine (C) is a class IA antiarrhythmic drug used for atrial and ventricular arrhythmias, but it has a higher risk of adverse effects compared to amiodarone.