What is the primary pharmacologic action of nitroglycerin?

What is the primary pharmacologic action of nitroglycerin?

• A. Vasoconstriction
• B. Vasodilation
• C. Positive inotropy
• D. Diuretic effect

Answer: (B)

Nitroglycerin’s primary action is to dilate vessels. It releases nitric oxide, which relaxes smooth muscle in the vascular walls, widening both veins (predominantly at typical therapeutic doses) and, at higher doses, arteries. This venodilation lowers preload, reduces left ventricular wall stress, and decreases myocardial oxygen demand, while improved coronary flow helps supply the heart muscle. This vasodilation is what relieves angina symptoms. It is not a vasoconstrictor, it does not increase contractility (positive inotropy), and it does not have a diuretic effect, so those options don’t fit.

Nitroglycerin’s primary action is to dilate vessels. It releases nitric oxide, which relaxes smooth muscle in the vascular walls, widening both veins (predominantly at typical therapeutic doses) and, at higher doses, arteries. This venodilation lowers preload, reduces left ventricular wall stress, and decreases myocardial oxygen demand, while improved coronary flow helps supply the heart muscle. This vasodilation is what relieves angina symptoms. It is not a vasoconstrictor, it does not increase contractility (positive inotropy), and it does not have a diuretic effect, so those options don’t fit.