CAMRT Radiography Practice Exam

During the preparation of contrast media, which medication is commonly used to pre-medicate patients with a contrast allergy?

1. Diphenhydramine

2. Metoclopramide

3. Diazepam

4. Acetaminophen

The correct answer is: Diphenhydramine

Diphenhydramine is commonly used to pre-medicate patients with a contrast allergy due to its properties as an antihistamine. Patients who have a known allergy to iodine-based contrast media may experience allergic reactions ranging from mild symptoms, such as urticaria (hives), to severe anaphylactic reactions. By administering diphenhydramine prior to the administration of contrast media, the risk of these allergic reactions can be reduced. Diphenhydramine works by blocking histamine receptors, thereby mitigating the body's allergic response. The other medications mentioned do not serve the same purpose. Metoclopramide is primarily used as an antiemetic to prevent nausea and vomiting and does not address allergic reactions. Diazepam is a benzodiazepine used for anxiety and sedation, which would not be effective in managing allergic reactions to contrast media. Acetaminophen is a pain reliever and fever reducer and is not an antihistamine, so it wouldn't help in preventing an allergic reaction. Therefore, diphenhydramine is the preferred choice for this situation.