Final answer:
The nurse should include the instruction to sit or lie down if dizziness or lightheadedness occurs when a patient is prescribed sustained-release oral nitroglycerin capsules for chronic stable angina.
Step-by-step explanation:
The nurse should include the instruction to sit or lie down if dizziness or lightheadedness occurs when a patient is prescribed sustained-release (extended release) oral nitroglycerin capsules for chronic stable angina. Nitroglycerin is a medication that dilates coronary arteries and improves blood flow, but it can cause dizziness or lightheadedness as a side effect. Therefore, it's important for the patient to take precautions to avoid injury in case these symptoms occur.