Before the nurse administers isosorbide mononitrate (Imdur), what is a priority nursing assessment?

• A. Assess serum electrolytes.
• B. Measure blood urea nitrogen and creatinine.
• C. Assess blood pressure.
• D. Monitor level of consciousness.

Answer: (C)

Isosorbide mononitrate lowers blood pressure by causing vasodilation, which reduces preload and afterload. Because the primary safety concern with nitrates is hypotension, the most important assessment before giving the medication is the patient’s blood pressure. If the blood pressure is too low or the patient has symptoms of hypotension (such as dizziness or faintness), the nurse should withhold the dose and notify the prescriber. Other assessments like electrolytes, renal function, or level of consciousness are not the immediate safety focus for this drug at the time of administration, since the drug’s main risk in this moment is hypotension from vasodilation.