Order: diphenhydramine 25 mg PO q6h, PRN

Available: diphenhydramine 12.5 mg/5 mL.

How many mL would the nurse give?

A) Subcutaneous:
The subcutaneous route involves administering medication into the layer of fat and connective tissue beneath the skin. This method is used for drugs that require slower absorption, such as insulin or certain vaccines.

B) Intramuscular:
The intramuscular route involves injecting medication directly into a muscle. This allows for faster absorption compared to subcutaneous injections, making it ideal for drugs that need to be absorbed quickly, such as vaccines or certain antibiotics.

C) Via a nasogastric tube:
Administering drugs via a nasogastric tube is not considered a parenteral route. The nasogastric (NG) tube delivers medications directly into the stomach via the gastrointestinal tract, which is not part of the parenteral system. Parenteral routes are those that bypass the digestive system, like injections.

D) Intradermal:
The intradermal route involves injecting medication just under the skin, in the dermis. This is typically used for allergy testing or tuberculosis screenings. It is a parenteral route because it bypasses the digestive system.

E) Intravenous:
The intravenous route involves injecting medication directly into a vein, offering rapid absorption and fast onset of action. This method is ideal for critical or emergency situations where immediate medication effects are necessary.

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.