A child is to receive 60mg of Phenytoin. The medication is available as an oral suspension that contains 150 mg/ml. How many milliliters should the nurse administer?

1. A

   0.4 ml

2. B

   2.2 ml

3. C

   2.6 ml

4. D

   2 ml

Appeared in: BHU NO-2019

Explanation

• The standard formula for dosage calculation is (Desired Dose / Available Dose) x Quantity.
• The desired dose is 60 mg, and the available concentration is 150 mg per 1 ml.
• Plugging the values into the formula: (60 mg / 150 mg) x 1 ml gives the correct volume.
• The calculation results in 0.4 ml, which is the precise volume needed to administer the prescribed 60 mg dose.

Why Other Options Were Wrong

• Option B: This is a mathematical error. Administering 2.2 ml would result in a dose of 330 mg (2.2 x 150), which is more than five times the prescribed dose and constitutes a major overdose.
• Option C: This is a significant mathematical error. Administering 2.6 ml would deliver a dose of 390 mg (2.6 x 150), which is more than six times the prescribed dose and extremely dangerous.
• Option D: This is a calculation error. Administering 2 ml would result in a dose of 300 mg (2 x 150), which is five times the prescribed dose and a dangerous overdose.

Related Visual

Clinical Relevance

• Nursing practice connection: Use the key finding related to Pediatric Dosage Calculation to guide bedside assessment, documentation, and the next nursing action.
• Accurate medication calculation is a fundamental nursing responsibility to ensure patient safety and prevent dosing errors, which can have severe consequences, especially in pediatric patients.
• For high-alert medications like Phenytoin (an anticonvulsant), it is best practice for two nurses to independently verify the dose calculation before administration to minimize the risk of error.
• What if the medication was available as a 30 mg/5 ml suspension? The calculation would change to (60 mg / 30 mg) x 5 ml = 10 ml. This highlights how critical it is to check the available concentration for every calculation.

How to Approach the Question

• First, identify the key pieces of information given in the problem: the desired dose, the available dose, and the quantity (volume) the available dose comes in.
• The 'Desired' dose is what the doctor ordered: 60 mg.
• The 'Available' or 'Have' dose is the concentration of the drug on hand: 150 mg.
• The 'Quantity' is the volume that contains the available dose: 1 ml.
• Apply the universal formula for dosage calculation: (Desired / Available) x Quantity.
• Substitute the values into the formula: (60 / 150) x 1.

Concept Tested & Keywords

• Concept Tested: Pediatric Dosage Calculation
• Stem keywords: child, receive, 60mg, Phenytoin, oral suspension, 150 mg/ml
• Lead-in keywords: How many milliliters
• Clinical cues: Age/sex group narrows the expected diagnosis, intervention, or normal reference range.

Question ID

QayrhBwioYJR8uad7HZcaj

Copy ID

Reference Book

E6 Nursing Fundamentals Potter Perry 12e Part 3 p. 142-144

E6 Pharmacology Nurses Shanbhag 3e p. 52-54