A nurse is providing teaching to a client who has angina and a new prescription for sublingual nitroglycerin tablets. Which of the following instructions should the nurse include in the teaching?

Choice A rationale Sublingual nitroglycerin is an acute treatment for angina. The client should take one tablet at the onset of pain, wait five minutes, and if the pain is not relieved, call emergency services and take a second tablet. They can take a third tablet five minutes after the second, but no more than three total doses within a 15-minute period. Choice B rationale The dose of sublingual nitroglycerin is one tablet at the onset of chest pain. Taking two tablets at once can lead to a sudden and significant drop in blood pressure due to its vasodilatory effects, causing dizziness, fainting, or reflex tachycardia, which can worsen myocardial ischemia. Choice C rationale Nitroglycerin is not used as a prophylactic medication to be taken hours before exercise. It is an acute treatment for an ongoing anginal episode. The medication works by relaxing vascular smooth muscle, causing vasodilation and increased coronary blood flow, which relieves the chest pain of angina. Choice D rationale Unused tablets should be stored in their original airtight, dark glass container at room temperature, away from light and heat. Exposure to light, moisture, or extreme temperatures can cause the medication to lose its potency, making it ineffective during an anginal attack.