Which of the following is a contraindication for administering nitroglycerin in adults?

The correct answer is based on the importance of blood pressure in the context of administering nitroglycerin. Nitroglycerin is a vasodilator commonly used to relieve angina and other conditions related to heart disease. However, it can cause a significant drop in blood pressure, which can lead to complications such as syncope or shock, particularly in adults who already have low blood pressure.

When the systolic blood pressure (SBP) is less than 100 mmHg, evidence suggests that the patient is at increased risk for adverse effects from nitroglycerin. While specific protocols may vary, the general contraindication for administering nitroglycerin is when the SBP is below this threshold, as the medication could exacerbate hypotension and result in serious harm.

Other options provided, such as age over 75, recent use of antibiotics, or SBP less than 90 mmHg, do not directly relate to the immediate contraindications for nitroglycerin administration as critically as SBP less than 100 mmHg. While patients with an SBP less than 90 mmHg are at risk and typically would not receive the medication, the more precise threshold generally recognized is indeed less than 100 mmHg. Therefore, it's crucial