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Difficulty: MediumPharmacological and Parenteral Therapies

A client is admitted to the medical-surgical unit and is receiving a continuous intravenous (IV) infusion of 5%5\% dextrose in water (D5W) at 75 mL/hr75 \text{ mL/hr}. To manage newly developed focal seizure activity, the healthcare provider prescribes a stat dose of phenytoin 100 mg100 \text{ mg} IV push. Which action by the nurse is the most appropriate?

  1. A
    Administer the medication rapidly over 30 seconds30 \text{ seconds} into the Y-port closest to the client to immediately achieve therapeutic levels.
  2. B
    Dilute the phenytoin in a 50 mL50 \text{ mL} bag of 5%5\% dextrose in water and infuse it as a secondary piggyback over 30 minutes30 \text{ minutes}.
  3. Stop the IV infusion, flush the line with 0.9%0.9\% sodium chloride, administer the phenytoin over 2 minutes2 \text{ minutes}, and flush again with 0.9%0.9\% sodium chloride.Answer
  4. D
    Pause the continuous D5W infusion, inject the phenytoin directly into the lowest IV port, and immediately resume the D5W infusion.

Answer

Stop the IV infusion, flush the line with 0.9%0.9\% sodium chloride, administer the phenytoin over 2 minutes2 \text{ minutes}, and flush again with 0.9%0.9\% sodium chloride.
Phenytoin is highly incompatible with dextrose-containing solutions and will rapidly precipitate if mixed. Therefore, the primary D5W infusion must be stopped, and the line must be thoroughly flushed with 0.9%0.9\% sodium chloride (normal saline) before and after administration. Additionally, phenytoin must be administered slowly (not exceeding 50 mg/min50 \text{ mg/min}) to prevent severe hypotension and cardiac arrhythmias; therefore, pushing a 100 mg100 \text{ mg} dose evenly over 2 minutes2 \text{ minutes} is the correct and safe rate.

Step-by-Step Solution

1
Assess the compatibility of the prescribed medication (phenytoin) with the currently infusing primary IV fluid (D5W).
Phenytoin is determined to be highly incompatible with dextrose.
Mixing phenytoin with any dextrose-containing solution causes immediate crystallization and precipitation, which can obstruct the IV line and harm the client.
2
Determine the appropriate administration technique to prevent drug-drug interaction in the IV tubing.
The IV line must be thoroughly flushed with a compatible solution (0.9%0.9\% sodium chloride) both before and after the phenytoin is given.
Flushing clears the residual dextrose from the tubing, creating a safe environment for the phenytoin to pass through without precipitating.
3
Calculate the safe rate of administration for the prescribed dose of 100 mg100 \text{ mg}.
The medication must be administered slowly over a minimum of 2 minutes2 \text{ minutes}.
The maximum safe IV push rate for phenytoin is 50 mg/min50 \text{ mg/min}. Rapid administration can induce severe cardiovascular toxicity, including hypotension and arrhythmias.

Key Concept

Phenytoin IV administration safety and compatibility
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Topics

Pharmacological and Parenteral Therapies

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