Pharmacology Part 1: Patient History & Administration (ARRT Registry Review)

There’s a quiet threshold every radiologic technologist crosses in training—a moment when you realize that contrast administration is not just a procedural task. It is a legal responsibility, an ethical commitment, and a test of your skill under pressure.

Pharmacology in radiologic technology is not abstract theory. It is the art of knowing who your patient is, what is safe for them, and how the contrast agent you’re about to administer will behave inside their body. And in that space, your preparation matters. Your precision matters. Your ability to gather, reconcile, interpret, and act on patient history matters.

This is why patient history and contrast administration form the backbone of pharmacology competency on the ARRT Registry and in real-world imaging departments. They shape your judgment long before you ever pick up a syringe.

Let’s walk through these principles in the same deliberate, structured way your uploaded materials present them—while expanding them with the clarity and depth needed to transform you from a student into a thoughtful, aware technologist.

1. Patient History: The First Safeguard

Before contrast is ever introduced, before a single button is pressed, there is history. Not the broad narrative of someone’s life, but a focused and precise excavation of information that protects your patient from harm.

A. Medication Reconciliation: Seeing the Whole Picture

Medication reconciliation is more than asking, “Are you taking any medications?” It is an intentional process:

Step 1: Gather a complete list.
Prescription medications, over-the-counter drugs, vitamins, supplements—everything.

Step 2: Clarify changes.
Has the patient recently stopped blood thinners? Switched doses? Missed a scheduled medication? These details change how you proceed.

Step 3: Compare with the medical record.
The lecture transcript highlights this clearly: sometimes postoperative patients stop prophylactic anticoagulants earlier than documented—or the chart may be outdated. Your job is to reconcile, not assume.

Step 4: Resolve discrepancies.
If something doesn’t make sense, you pause. You ask. You document. You escalate as needed.

Why all this precision? Because certain medications alter how patients respond to contrast.

Metformin: The Big Red Flag

The transcript emphasizes metformin for a reason.
It carries a rare but lethal risk: metformin-associated lactic acidosis.
The numbers are small—less than one case in a thousand—but the mortality rate hovers around 50%.

This is why patients are often instructed (site-specifically) to hold metformin for 48 hours after iodinated contrast and sometimes obtain follow-up labs.

For the registry and clinical practice, remember:
It isn’t the contrast alone that’s dangerous—it’s how contrast interacts with pre-existing renal status and medications.

Blood Thinners: The Hidden Aftermath

Blood thinners—Eliquis, heparin, Lovenox, warfarin, even baby aspirin—don’t contraindicate contrast.
But they do change what you must prepare for.

The transcript highlights extended bleeding time after IV removal, increased bruising, and the importance of informing the patient so they’re not alarmed.

This is what separates a novice from a growing professional: anticipating downstream effects of tiny actions.

B. Premedications: When the Patient Has a History of Reaction

Premedication protocols vary by site, but the uploaded lecture material gives a clear pattern:

• Antihistamines

• Corticosteroids

• Often administered 12 hours prior

• Accelerated IV protocols in the emergency department

Your responsibility?

Ensure the patient actually received their premedication.
Verify the timing.
Verify the dosage.

If the regimen wasn’t followed, you don’t proceed.
This is not optional. This is legal, ethical, and clinical safety.

C. Contraindications: When to Stop

The transcript offers one unambiguous, universal stop sign:

A previous anaphylactic or bronchospasm reaction to iodinated contrast.

Mild or moderate reactions may be site-specific contraindications, but severe reactions require immediate escalation. That is your responsibility.

Other contraindications come from the exam itself:

• Suspected bowel perforation → avoid barium, use iodinated contrast instead.

• Breast cancer mastectomy with lymph node removal → never use that arm for IV access.

History becomes the map. Contrast becomes the stress test. Your judgment becomes the safeguard. 

Patient history lays the foundation. But in radiologic technology, story must eventually become action. That action begins with administration—the moment when medication, contrast, or preparation enters the patient’s body. It is here that the technologist’s clarity, technique, and precision are tested.

Contrast administration is not just a series of steps.
It is a choreography of safety.

Everything you do—from choosing the route of administration to selecting supplies, calculating dose, and performing venipuncture—reveals the kind of technologist you are becoming.

Let us explore these components exactly as your documents outline, while drawing out the deeper meaning beneath the procedure.

2. Administration: The Art and Science of Delivery

The uploaded pharmacology documents outline four core areas of administration:

1. Routes of delivery

2. Supplies

3. Technique

4. Contrast dose calculation

Each of these is a competency. Combined, they become a craft.

A. Routes of Administration: Pathways Into the Body

The route determines how quickly medication acts, how it is absorbed, and how the patient experiences it. For radiologic technologists, the primary routes include:

1. Intravenous (IV)

This is the most immediate route, producing rapid physiologic effects and quick distribution of contrast. As the transcript emphasizes, IV contrast is delivered directly into the bloodstream—bypassing digestion and metabolism—making accuracy crucial.

IV access requires:

• Proper assessment of veins

• Clean technique

• Correct needle selection

• Knowledge of flow rates

• Awareness of patient reactions

2. Oral

Oral contrast moves through the digestive tract and requires advanced preparation time. Patients must be instructed precisely—what to drink, when to drink it, how long it will take to reach the desired anatomy.

The Patient Care manual highlights this: oral medications and agents must be timed carefully to avoid delaying the exam.

3. Rectal (via enema kits)

The documents describe rectal administration as essential for lower GI studies. Here, the technologist must understand:

• Enema bag height

• Proper insertion technique

• Patient comfort

• Prevention of leakage

• Slow, controlled delivery

The route may be simple, but the skill is not.

4. Other Routes

While less common in routine radiography, radiologic technologists must recognize additional routes listed in the materials—such as intrathecal for myelography and topical for deodorizing skin prep—primarily to understand contrast workflow and documentation.

The ARRT® is less concerned with mastery of every route and more interested in whether you understand why a route is chosen and how it affects patient safety.

B. Supplies: Tools That Become Extensions of Your Hand

The uploaded documents list a series of supplies every technologist must master:

• Needles

• Syringes

• IV catheters

• Tourniquets

• Alcohol wipes

• Enema kits

• Lubricants

• Contrast bottles

• Extension tubing

• Gauze and tape

What separates a skilled technologist from an average one is not simply knowing what each item is—but knowing why you choose one over another.

Needle Gauge Selection

The transcript notes that you select gauge based on:

• Vein size

• Contrast viscosity

• Flow rate

Large-bore needles (such as 18–20 gauge) are needed for rapid bolus injections used in CT.
Smaller gauges (22–24) are for delicate or compromised veins.

Gauge selection becomes a blend of anatomy, physics, and compassion.

C. Procedural Technique: Venipuncture as a Professional Ritual

Venipuncture is one of the few invasive skills radiologic technologists perform. It requires confidence, patience, and a steady commitment to aseptic technique.

The uploaded documents outline the steps methodically:

1. Verify physician order

2. Confirm patient identity

3. Apply tourniquet

4. Select a vein

5. Clean the site

6. Insert needle bevel up

7. Confirm blood flash

8. Advance catheter

9. Remove needle

10. Flush and secure

The steps may appear simple on paper, but the experience of performing them is anything but. Your voice, your presence, your calmness—all become just as important as the technical act.

A patient remembers your hands long after they forget the image.

D. Contrast Dose Calculation: Precision as Protection

The most critical mathematical skill in radiologic pharmacology is dose calculation. Your materials emphasize weight-based formulas—typically mL per kg—and technique-based variations depending on:

• Patient size

• Age

• Kidney function

• Type of examination

• Type of contrast

Dose is not a guess.
It is a deliberate calculation rooted in physiology and guided by departmental policy.

The real test of a technologist is not how quickly they calculate dose—but how carefully they confirm it.

There is a moment in every radiologic technologist’s development when pharmacology begins to feel less like memorization and more like stewardship. You’re no longer checking boxes or following scripts—you’re protecting a human life by understanding what enters their body, how it moves, and what it may disturb.

The final dimension of this protection lies not only in what you administer, but when, and to whom.

3. Scheduling and Sequencing: The Hidden Logic of Radiologic Pharmacology

Your uploaded materials highlight a subtle but essential reality: the sequence and timing of exams have pharmacologic consequences.

This is not simply workflow management.
It is patient safety.

A. Barium Studies Take Priority

Once a patient receives barium—whether oral or rectal—it coats the GI tract. Any exam requiring visualization of soft tissues or bones becomes obscured. For this reason:

• Barium studies are always scheduled last.

Performing an abdominal CT after a barium swallow?
Impossible.

Trying to visualize the kidneys after barium enema contrast coats the colon?
Futile.

Scheduling becomes a kind of pharmacologic chess game.

B. Iodinated Contrast Exams Precede Barium

The patient care document notes the sequence clearly:

1. Non-contrast studies

2. Iodinated contrast exams

3. Barium studies

This sequence prevents barium from interfering with absorption, excretion, or imaging of iodinated contrast.

C. NPO and Contrast Timing

NPO status is not a formality.
It prepares the stomach and small bowel for contrast ingestion or administration. It reduces aspiration risk. It enhances exam clarity.

Understanding why the patient is NPO, and for how long, reflects a technologist’s maturity.

4. Bringing Patient History and Administration Together

The power of pharmacology lies in integration. The uploaded lecture transcript underscores this again and again: history informs administration, and administration must never ignore history.

A. Contraindications Revisited

Contrast contraindications fall into three clinical categories drawn from your documents:

1. Medication-based

   • Metformin (risk of lactic acidosis)

   • Recent nephrotoxic drugs

2. Physiologic

   • Impaired renal function

   • Recent severe contrast reaction

   • Compromised venous access

   • Severe dehydration

3. Procedure-based

   • Suspected bowel perforation (avoid barium)

   • Mastectomy with lymph node dissection (avoid using that arm)

Every contraindication exists to prevent a predictable harm.
This is why the ARRT® expects you not only to recognize them, but to act on them.

B. The Dialogue That Protects the Patient

Pharmacology becomes personal when you ask the right questions:

• “Have you ever had a reaction to contrast before?”

• “Do you have kidney problems?”

• “When was the last time you took your metformin?”

• “Are you taking blood thinners?”

These are not casual questions.
They are clinical tools.

Your calm voice, your ability to listen without rushing, and your willingness to escalate concerns—these qualities transform the interview into patient protection.

5. The Technologist’s Presence During Administration

The documents emphasize something more profound than technique: your presence matters during administration.

You must:

• Observe the injection site

• Watch for extravasation

• Monitor the patient’s breathing

• Listen for changes in their voice

• Assess for warmth, itching, cough, or anxiety

• Recognize early signs of reaction

The first 30 seconds after injection often reveal everything.
Your eyes and ears become diagnostic instruments.

Contrast reactions, though rare, occur in gradients:

• Mild: itching, sneezing

• Moderate: hives, vomiting

• Severe: laryngeal edema, hypotension, bronchospasm

Your documents stress the seriousness of severe reactions, especially those involving airway compromise.
This is why your preparation—knowing where emergency equipment is, reviewing reaction protocols, ensuring someone is nearby—is non-negotiable.

A technologist’s vigilance can turn crisis into stability.

6. Ethical Precision: The Pharmacologic Mindset

The most striking theme in your uploaded materials is this: safe pharmacology is not memorization; it is mindset.

The mindset includes:

• Doing things in the correct sequence

• Pausing when something feels off

• Reconciling medications even when rushed

• Confirming premedication compliance

• Respecting contraindications even when pressured to “just get it done”

• Verifying dose calculations without shortcuts

In radiologic technology, contrast administration becomes a mirror.
It reflects the kind of professional you are becoming.

You learn that:

Precision protects.
Presence reassures.
Preparation saves.

Great technologists are not defined solely by how well they position a patient or manipulate exposure factors. They are defined by their ability to think pharmacologically—to connect patient history, procedural knowledge, and physiologic insight into one seamless, protective decision-making process.

7. Closing Reflection: Becoming a Steward of Patient Safety

Pharmacology in radiologic technology is not about drugs.
It is about people.

It is about understanding how a medication can heal, harm, or reveal.
It is about remembering that contrast is more than a tool—it is a substance capable of transforming the body’s internal portrait.

As you prepare for the ARRT® exam, do not rush through these concepts.
Let them settle. Let them shape the way you see patients.

Because when you stand in that procedure room—needle in hand, contrast warming in the injector—your patient does not see pharmacology. They see you.

And what they need most in that moment is a technologist who:

• Knows the history

• Understands the risks

• Masters the technique

• Values the sequencing

• Calculates the dose with precision

• And administers with a calm, attentive presence

This is how you reach your full potential.