A nurse is reviewing the list of current medications for a client who has a new prescription for nitroglycerin. The nurse should identify that which of the following client medications is contraindicated for use with nitroglycerin?

A. Gemfibrozil is a lipid-lowering agent and does not have a significant interaction with nitroglycerin. It is not contraindicated for use with nitroglycerin. B. Lansoprazole is a proton pump inhibitor used to treat acid-related stomach issues. It does not interact with nitroglycerin and is safe to use concurrently. C. Diazepam is a benzodiazepine used for anxiety and muscle spasms. While it can cause hypotension, it is not specifically contraindicated with nitroglycerin. D. Sildenafil is a phosphodiesterase inhibitor used to treat erectile dysfunction. It is contraindicated with nitroglycerin because both medications cause vasodilation, which can lead to severe hypotension and cardiovascular collapse. Patients should not use these medications together.