Essential Pharmacology for X-Ray Students: What You Need to Know for the ARRT Exam and Clinical Practice
May 23, 2025The Role of Pharmacology in Radiologic Technology
Passing the ARRT Radiography Registry Exam requires more than technical knowledge of positioning and radiation safety. It demands a well-rounded understanding of the clinical responsibilities that radiologic technologists shoulder every day. One of the most overlooked yet essential areas of knowledge is pharmacology—the study of drugs, their effects, and their uses. In radiologic practice, this includes understanding medications, contrast agents, and emergency drugs that may appear in the imaging suite. Whether you’re a student preparing for the exam or a new technologist trying to build confidence in the clinical setting, this blog post is your guide to the pharmacological concepts you’re likely to encounter—and how to apply them responsibly.
Why Pharmacology Matters in Radiography
Pharmacology might not be the first thing you associate with radiography, but it’s a crucial part of patient care. Radiologic technologists are often the first to notice signs of a reaction to contrast agents, are expected to be aware of drug contraindications, and must be able to assist during emergencies. Even though we don't routinely administer medications, we are frontline healthcare professionals. Our understanding of these substances can be the difference between a routine exam and a medical emergency.
Understanding Contrast Agents: Barium Sulfate
Let’s start with contrast agents, which are integral to enhancing imaging quality and diagnostic accuracy.
One of the most common is barium sulfate. This white, powdery substance is mixed with water to create a suspension that patients either drink or receive rectally. You've likely used this in studies like upper GI series, barium enemas, or modified barium swallows. It works by coating the lining of the gastrointestinal tract, providing a clear outline on X-rays due to its radiopaque properties. Since barium sulfate is not absorbed by the body, it’s generally safe, but it has limitations. If there is any suspicion of GI perforation, it should be avoided. In such situations, using an iodinated contrast agent is much safer to prevent complications like barium peritonitis.
Iodinated Contrast: Safety and Application
Speaking of iodinated contrast, these agents are essential in cross-sectional imaging like CT, angiography, or venography. Examples include Omnipaque (iohexol) and Isovue (iopamidol). What’s important to understand is the distinction between ionic and non-ionic types. Ionic contrasts, with their high osmolality, have a greater likelihood of causing side effects such as a feeling of warmth, nausea, or even allergic-like reactions. Non-ionic contrasts are less reactive and preferred in sensitive populations. Regardless of the type, all iodinated contrasts carry a risk, and you must always be prepared to act if a reaction occurs. Imagine performing a contrast-enhanced CT scan when your patient suddenly begins coughing, develops hives, or shows signs of distress. It’s your responsibility to recognize the signs, call for help, and know where the emergency supplies and medications are kept.
Epinephrine: A Lifesaving Emergency Drug
That leads us to epinephrine, one of the most critical drugs you should recognize. Epinephrine is the go-to medication for anaphylactic reactions. In such emergencies, time is of the essence. Administered intramuscularly or intravenously, epinephrine quickly reverses the symptoms by stimulating the heart, opening the airways, and increasing blood flow. You may not administer it yourself, but knowing when it’s needed and helping the code team can save lives.
Atropine: Responding to Bradycardia
Another drug worth understanding is atropine. It’s commonly used when patients experience bradycardia, or an unusually slow heart rate. This might happen during procedures involving vagal stimulation or as a reaction to certain drugs. Atropine works by blocking parasympathetic signals, allowing the heart rate to normalize. It’s a staple in crash carts, and being aware of when and why it's used makes you a more capable member of any radiology team.
Nitroglycerin: Managing Chest Pain
Now consider a patient who suddenly experiences chest pain. This might indicate angina, especially if they have a cardiac history. Nitroglycerin is a vasodilator that helps by reducing the heart’s workload and improving oxygen delivery. Often administered sublingually, its rapid action makes it an excellent tool in preventing more severe cardiac events. If a patient mentions they’ve brought their nitroglycerin or you notice they are showing symptoms while waiting for their MRI, alerting the nurse or radiologist quickly is your responsibility.
Diphenhydramine: Treating Mild Allergic Reactions
Emergency drugs aren't the only ones that matter. Diphenhydramine, commonly known as Benadryl, is frequently used to treat mild contrast reactions such as itching or hives. Administered either orally or intravenously, it acts by blocking histamine receptors. In cases where a patient has a history of mild allergies to contrast, pre-medicating with diphenhydramine may be part of the imaging protocol.
Glucagon: Aiding Gastrointestinal Imaging
You might also encounter glucagon. While it's more common in GI studies than in emergencies, it's a great example of how pharmacology is used to improve diagnostic results. Glucagon slows down the movement of the stomach and intestines, making it easier to capture detailed images. But like any medication, it’s not without its risks—particularly in diabetic patients where it can elevate blood glucose levels.
Anxiolytics: Supporting Patients with Anxiety
Patients with anxiety or claustrophobia may need support when facing long or tight imaging exams. In these cases, mild anxiolytics such as diazepam or lorazepam are sometimes prescribed. You won’t be administering these, but it’s essential to know they’ve been taken. Be vigilant for signs of sedation or confusion post-procedure and ensure patients don’t drive themselves home afterward.
Metformin and Contrast: A Dangerous Combination
And then there’s metformin—a medication millions of people take for Type 2 diabetes. The concern arises when this drug is combined with iodinated contrast, which can temporarily affect kidney function. If the kidneys are impaired and metformin isn’t cleared properly, a rare but serious condition called lactic acidosis can occur. This is why many facilities have protocols to pause metformin before and after imaging procedures involving contrast. It’s your role to confirm these instructions have been followed and communicate with the patient if there’s any doubt.
Study Tips for Mastering Pharmacology
So, how do you actually study all this?
Start by breaking the information into manageable pieces. Group medications by their use—contrast agents, emergency drugs, supportive medications—and study each group separately. Use flashcards to quiz yourself on key facts: the drug name, its use, how it’s administered, and any major side effects or contraindications. Apps like Anki are excellent for building your own decks. There's a link to their site at the end of this blog.
Engaging in Scenario-Based Learning
Don’t just study in isolation. Engage in scenario-based learning. For example, ask yourself: what would I do if a patient had a mild allergic reaction in the middle of a CT scan? What drugs should I be ready to assist with? What questions should I ask before administering contrast? These scenarios bring the material to life.
Reinforcing Knowledge Through Peer Teaching
Another great technique is peer teaching. Find a classmate or colleague and take turns explaining concepts to each other. Teaching someone else is one of the most powerful ways to reinforce your own knowledge. Create visuals, like flowcharts or infographics, to map out how different drugs are related and when each is used.
Pharmacology on the ARRT Exam: What to Expect
When it comes to the ARRT exam, pharmacology questions won’t ask you to diagnose or prescribe—but they will expect you to understand your role, know which medications are relevant, and identify red flags. It’s not about memorizing a pharmacy textbook; it’s about building situational awareness and clinical confidence.
Embracing Pharmacology as Part of Patient Care
Ultimately, pharmacology is one of the many ways you contribute to patient safety and care as a radiologic technologist. You’re part of the team that sees patients at their most vulnerable. Understanding the medications they’re exposed to—and being prepared to act when needed—elevates your competence and earns your patients’ trust.
Final Words: Be Prepared, Not Perfect
So as you review this material, remember: you don’t need to be perfect. But you do need to be prepared. Know the agents. Understand the actions. Recognize the risks. And most importantly—be ready to step up when it counts.
Deepen Your Learning with the 21 Day Registry Review Challenge
If you're ready to take a deeper dive into pharmacology and truly master these concepts for both the ARRT exam and clinical application, we invite you to join the 21 Day Registry Review Challenge.
Day 4: Focused Pharmacology Sessions
On Day 4: Patient Interactions & Management IV, we dedicate an entire day to pharmacology, breaking it down into focused, easy-to-digest sessions taught by expert instructors:
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Session Number One: Patient History and Administration with Lisa Dostick
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Session Number Two: Contrast Media Types & Properties, Appropriateness of Contrast Media with Jacki Harmon
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Session Number Three: Complications medications and their Reactions with Christy Mauel
Live Q&A for Real-World Insights
At the end of the day, Get your questions answered and gain real-world insights from these three educators at the live Q&A panel discussion.
Join Today to Elevate Your Clinical Readiness
These sessions are crafted to help you connect theory to practice—whether you're prepping for the exam or navigating the challenges of clinicals.
Visit RadTechRegistry.com to learn more and sign up. Investing in your success today sets the tone for your future in radiography.
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