Which two adverse effects should prevent the use of dipyridamole alone in elderly patients?

Dipyridamole, when used as a monotherapy, can indeed pose specific risks, particularly in elderly patients, due to its pharmacological profile. Two notable adverse effects that warrant concern are gastrointestinal (GI) issues and orthostasis.

GI issues, including symptoms like nausea, diarrhea, and abdominal pain, can be particularly problematic in the elderly, who may already have a compromised gastrointestinal system or be on multiple medications that affect GI motility. Furthermore, orthostasis, or a drop in blood pressure upon standing, can lead to dizziness and falls, which are significant risks for this population, making it crucial to avoid agents that may exacerbate these conditions.

In contrast, while hypertension and tachycardia, headache and nausea, as well as fatigue and dizziness are adverse effects that might occur, they do not evenly highlight the specific concerns related to the elderly and their heightened vulnerability to GI disturbances and instability in blood pressure. The combination of these two risks makes the use of dipyridamole as a standalone treatment particularly ill-advised for elderly individuals.