A 65-year-old seizure patient requires an IV phenytoin loading dose. Which IV fluid should not be used for di… - NORCERT 8 Mains-2025

NORCERT 8 Mains-2025

Pharmacology

Easy

Appeared in: NORCERT 8 Mains-2025

Explanation

Phenytoin is chemically incompatible with dextrose-containing solutions like D5W.
Mixing phenytoin, which is highly alkaline (pH ~12), with the acidic D5W causes the drug to precipitate, forming visible crystals.
This precipitation can lead to loss of drug efficacy, occlusion of the IV line, and potentially fatal emboli if infused.

Option A: This is the recommended and compatible diluent for IV phenytoin. It is the standard of care for administering this medication.
Option C: This solution is also considered incompatible with phenytoin. The presence of electrolytes like calcium in Lactated Ringer's can bind with phenytoin and cause precipitation.
Option D: Diluting phenytoin with sterile water is not recommended. The resulting solution would be hypotonic, which can cause hemolysis (destruction of red blood cells), and precipitation of the drug can still occur.

Visual 1: Comparison Image - Showing two IV bags side-by-side. One bag labeled 'Phenytoin in Normal Saline' contains a clear liquid. The other, labeled 'Phenytoin in D5W,' contains a cloudy liquid with visible white particles (precipitate).
Visual 2: Infographic - Illustrating the signs and symptoms of 'Purple Glove Syndrome,' showing discoloration, edema, and pain in the hand and arm, which is a severe complication of phenytoin extravasation.

Clinical Relevance

Nursing practice connection: Prioritize focused assessment, early escalation, and real-time monitoring when managing IV Drug and Fluid Compatibility in acute care settings.
Ensuring drug-fluid compatibility is a critical nursing responsibility to prevent patient harm, including loss of therapeutic effect and severe adverse reactions like embolism or tissue necrosis.
Always consult a drug compatibility chart, pharmacist, or reliable drug reference before mixing any IV medication, especially high-risk drugs like phenytoin.
What if? If a patient's only available IV line was previously running D5W, the nurse must first stop the D5W infusion, flush the line thoroughly with a sufficient amount of Normal Saline (e.g., 10-20 mL), administer the phenytoin (diluted in NS), and then flush again with NS before restarting any other incompatible fluid.

How to Approach the Question

Identify the core of the question: It's about medication safety and IV compatibility for a specific drug.
Identify the drug: Phenytoin. Recognize this as a high-alert medication with known, specific administration protocols.
Recall or look up the specific IV dilution requirements for phenytoin. The key fact to remember is its profound incompatibility with dextrose.
Analyze the options: Evaluate each IV fluid against the known compatibility profile of phenytoin.
Select the option that is explicitly contraindicated. D5W is the classic and most dangerous example of an incompatible fluid for phenytoin.

Concept Tested & Keywords

Concept Tested: IV Drug and Fluid Compatibility
Stem keywords: phenytoin, IV loading dose, dilution, IV fluid
Lead-in keywords: should not be used
Clinical cues: Patient with seizures requiring a high-risk medication (phenytoin).
Negative lead-in flag: The question asks which fluid is contraindicated, requiring identification of an incompatible mixture.

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