Which of the following drugs is a mixed vasodilator?

Enalapril is a mixed vasodilator because it functions as an angiotensin-converting enzyme (ACE) inhibitor, which has effects on both the arterial and venous systems. By inhibiting the conversion of angiotensin I to angiotensin II, enalapril leads to vasodilation and decreases blood pressure. This dual action makes it effective in treating conditions like heart failure and hypertension, where reducing both preload and afterload is beneficial.

In contrast, the other drugs listed have more specific actions. Hydralazine primarily dilates arterioles, making it more of a selective vasodilator. Nitroglycerin primarily dilates venous vessels, which reduces preload but has limited direct effects on systemic vascular resistance. Propranolol is a beta-blocker that primarily affects heart rate and contractility, and while it can have some effects on vascular tone due to its influence on cardiac output, it is not classified as a vasodilator.

Thus, enalapril stands out as the drug that functions as a mixed vasodilator, affecting both the arterial and venous systems simultaneously.