A nurse is caring for a client who has hypertension and has a new prescription for lisinopril. The nurse should consult with the provider about a contraindication for which of the following medications in the client's medication administration record?

Lisinopril is an angiotensin-converting enzyme (ACE) inhibitor that lowers blood pressure by preventing the synthesis of angiotensin II. A significant secondary effect of ACE inhibition is the reduction of aldosterone secretion, which leads to the retention of potassium by the kidneys. This pharmacological action poses a severe risk of hyperkalemia, necessitating the avoidance of supplemental potassium sources during therapy. Rationale: A. Levothyroxine is a synthetic thyroid hormone that does not have a direct pharmacological contraindication with ACE inhibitors like lisinopril. While the nurse should always monitor for general drug interactions, there is no specific mechanism where lisinopril and levothyroxine interfere with each other's safety or efficacy. Patients with both hypertension and hypothyroidism can safely take these medications concurrently. B. Metformin is a biguanide used for the management of type 2 diabetes and is not contraindicated for use with lisinopril. ACE inhibitors are often the preferred antihypertensive for diabetic patients because they provide renal protection against diabetic nephropathy. The combination is considered clinically beneficial as long as the nurse monitors the patient's renal function and glucose levels regularly. C. Potassium chloride is contraindicated for concurrent use with lisinopril because both medications contribute to elevated serum potassium levels. ACE inhibitors decrease aldosterone, which normally facilitates potassium excretion; adding a potassium supplement can lead to life-threatening hyperkalemia. This electrolyte imbalance can cause fatal cardiac arrhythmias, making it essential to clarify this prescription with the provider immediately. D. Acetaminophen is a non-opioid analgesic and antipyretic that is generally safe to use for patients taking lisinopril for hypertension. Unlike non-steroidal anti-inflammatory drugs (NSAIDs), acetaminophen does not typically interfere with the blood pressure-lowering effects of ACE inhibitors or impair renal blood flow. It remains a safe choice for mild pain management in this patient population.