When administering an antianginal drug such as nitroglycerin (NTG) the nurse identifies which as the most common response.

A) Bradycardia
Bradycardia (a slow heart rate) is not the most common response to nitroglycerin (NTG). While NTG can affect heart rate in some individuals, its primary action is related to blood vessels, and it typically leads to vasodilation, which more commonly results in reflex tachycardia (an increased heart rate), rather than bradycardia.

B) Tachycardia
Tachycardia (an increased heart rate) can occur as a compensatory mechanism when nitroglycerin causes vasodilation and a decrease in blood pressure. However, this is more of a secondary effect. The primary action of nitroglycerin is to lower blood pressure (by dilating blood vessels), and in response to the lowered blood pressure, the body may try to compensate by increasing the heart rate.

C) Hypotension
The most common and primary response to nitroglycerin (NTG) administration is hypotension. Nitroglycerin works by relaxing smooth muscle in blood vessels, leading to vasodilation (widening of blood vessels). This reduces the amount of work the heart has to do and lowers the overall blood pressure. Hypotension is expected as part of the therapeutic effect of NTG, especially with a larger dose or rapid administration (e.g., sublingual NTG).

D) Dry mouth
While many medications can cause dry mouth (especially anticholinergic drugs), nitroglycerin is not typically associated with this issue. Its primary action is vasodilation, and while it can cause other symptoms like headaches, dizziness, and hypotension, dry mouth is not considered a common or significant effect.