Correct Answer: B

Rationale: Metoprolol is a beta-blocker commonly used in heart failure to reduce blood pressure. One of the common side effects of metoprolol is hypotension, which can lead to dizziness, lightheadedness, and even fainting. Therefore, monitoring for hypotension is essential to prevent adverse effects and ensure patient safety.

Correct Answer: C

Rationale: Hypokalemia increases the risk of digoxin toxicity as low potassium levels enhance the effects of digoxin on the heart, leading to toxicity and potential adverse effects.

Correct Answer: A

Rationale: Taking digoxin at the same time each day is essential to maintain a consistent blood level of the medication. This consistency helps optimize the therapeutic effects of digoxin in managing chronic heart failure. Deviating from the scheduled time could lead to fluctuations in drug levels, affecting its effectiveness and potentially causing harm.

Correct Answer: A

Rationale: Nitroglycerin tablets are light and moisture-sensitive, so they should be stored in a cool, dry place away from light to maintain their effectiveness. Option B advises taking a tablet every 5 minutes, which may lead to overdose. Option C emphasizes the correct administration route for sublingual tablets. Option D is incorrect as water is not needed for the tablets to take effect.

Correct Answer: A

Rationale: To monitor the effectiveness of warfarin therapy in a client with atrial fibrillation, the nurse should assess the Prothrombin time (PT) and international normalized ratio (INR) levels. These tests help determine the clotting ability of the blood and ensure that the client's anticoagulation levels are within the therapeutic range, reducing the risk of bleeding or clotting complications.