Which of the following is an example of a nitrate?

• A. Glyceryl trinitrate
• B. Fenofibrate
• C. Gemfibrozil
• D. Isosorbide dinitrate

Answer: (A)

Nitrates release nitric oxide to relax vascular smooth muscle and cause vasodilation. Glyceryl trinitrate is a classic nitrate ester (nitroglycerin) that rapidly donates NO when absorbed, producing venodilation and, at higher doses, some arterial dilation. This lowers venous return and myocardial oxygen demand, making it an iconic example of a nitrate used for acute angina. Fenofibrate and gemfibrozil are fibrates; they lower lipid levels by activating PPAR-alpha and do not release nitric oxide, so they are not nitrates. Isosorbide dinitrate is also a nitrate, but the commonly cited example in this context is glyceryl trinitrate, the prototypical nitrate.