Which medication is specifically not recommended for use in ACS if the systolic blood pressure is less than 90?

The medication that is specifically not recommended for use in acute coronary syndrome (ACS) when the systolic blood pressure is less than 90 is morphine. This is important because morphine can cause vasodilation, which may lower blood pressure further in these patients who are already hypotensive.

In the context of ACS, the goal is to manage pain and anxiety while ensuring that blood pressure remains within a safe range to support adequate perfusion to the heart and other vital organs. If a patient is already experiencing low blood pressure, using a medication that could exacerbate that condition may lead to worse outcomes.

Other medications listed, such as nitrates, beta blockers, and aspirin, have specific indications and can be used in other contexts with careful monitoring of blood pressure and overall patient status. However, morphine's potential effects on blood pressure make it a medication to avoid in this particular scenario.