NCLEX-PN® ExaminationPharmacological TherapiesHard
A client is ordered to receive a loading dose of phenytoin 1,000 mg IV at a rate not to exceed 50 mg/minute. The pharmacy provides phenytoin 50 mg/mL. The LPN needs to calculate the maximum volume of phenytoin solution that can be administered per minute. What is the maximum rate in mL/minute?
- A1 mL/minute
- B2 mL/minute
- C5 mL/minute
- D0.5 mL/minute
Show answer & explanationAnswer & explanation
Correct answer: A. 1 mL/minute
To calculate the maximum volume per minute, divide the maximum allowed dose per minute by the concentration of the medication. 50 mg/minute / 50 mg/mL = 1 mL/minute.
Why the other options are wrong
- B. Incorrect calculation. This would be 100 mg/minute.
- C. Incorrect calculation. This would be 250 mg/minute.
- D. Incorrect calculation. This would be 25 mg/minute.
Phenytoin IV Infusion Rate
Phenytoin IV infusion rates must be carefully controlled, typically not exceeding 50 mg/minute, to prevent adverse cardiac effects like hypotension and arrhythmias.
- Phenytoin IV max rate: 50 mg/minute.
- Faster rates risk hypotension, arrhythmias.
- Calculate mL/minute based on concentration.
- Dilution may be required before administration.
Memory trick: PHENYTOIN: Prevent Heart Event, No Fast Infusion