A patient with CAD is prescribed nitroglycerin sublingually. Which of the following instructions should the nurse provide?

Choice A rationale Nitroglycerin works by relaxing vascular smooth muscle, primarily in veins, reducing preload and myocardial oxygen demand. The standard protocol for chest pain is to take one sublingual tablet, and if pain persists, repeat the dose every five minutes for a maximum of three doses in a 15-minute period. If the pain persists after three doses, the patient should seek emergency medical care. Choice B rationale Sublingual administration of nitroglycerin is designed for rapid absorption directly into the bloodstream through the mucous membranes under the tongue. Chewing the tablet would lead to slower and less predictable absorption because the medication would be swallowed and metabolized by the liver, reducing its bioavailability and effectiveness. Choice C rationale Nitroglycerin is a volatile compound that is sensitive to heat, light, and moisture. Storing the medication in a humid environment can cause it to lose its potency, rendering it ineffective when needed to treat acute angina. It should be kept in its original dark glass container, tightly capped, in a cool, dry place. Choice D rationale Alcohol can potentiate the hypotensive effects of nitroglycerin, leading to a significant and potentially dangerous drop in blood pressure. Combining these substances can cause severe orthostatic hypotension, syncope, and an increased risk of falls, making it a dangerous interaction that patients should be explicitly warned against.