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

Rationale: A. "Massage the ointment into the skin.": The ointment should not be massaged into the skin because doing so alters the absorption rate and can cause unpredictable vasodilation and hypotension. B. "Spread the ointment in a thin, even layer.": The nurse should instruct the client to apply the prescribed amount of nitroglycerin ointment in a thin, even layer to a hairless area of the upper body or chest. This ensures consistent absorption of the medication. C. "Apply the ointment to the forearm.": The forearm is not a recommended site for application. The preferred areas are the chest, back, or upper arm where the skin is less likely to be disturbed and has better absorption. D. "Apply the ointment to the skin every 4 hr.": Nitroglycerin ointment is usually applied every 6 to 12 hours depending on the prescription, with a nitrate-free interval to prevent tolerance. Every 4 hours is not standard practice.