The prescription order is for $250\mathrm{mg}$ of a drug to be given to a patient. The drug vial reads $500\mathrm{mg / ml}$. How much of the drug should the nurse give?

1. A

   2 ml

2. B

   1 ml

3. C

   0.5 ml

4. D

   0.25 ml

Appeared in: IGNOU PB. Bsc. Nsg. Entrance-2025

Explanation

• The standard formula for calculating medication dosage is: (Dose Desired / Dose on Hand) × Quantity.
• The desired dose is 250 mg, and the dose on hand is 500 mg in a quantity of 1 ml.
• Applying the formula: (250 mg / 500 mg) × 1 ml results in 0.5 ml.
• Therefore, the nurse should administer 0.5 ml to deliver the prescribed 250 mg dose.

Why Other Options Were Wrong

• Option A: Administering 2 ml would deliver 1000 mg of the drug (2 ml × 500 mg/ml), which is four times the ordered dose and a significant medication error.
• Option B: Administering 1 ml would deliver 500 mg of the drug (1 ml × 500 mg/ml), which is double the ordered dose.
• Option D: Administering 0.25 ml would deliver 125 mg of the drug (0.25 ml × 500 mg/ml), which is only half of the ordered dose.

Related Visual

Clinical Relevance

• Nursing practice connection: Use the key finding related to Medication dosage calculation to guide bedside assessment, documentation, and the next nursing action.
• Accurate medication calculation is a fundamental nursing responsibility critical for patient safety. Errors can lead to underdosing (ineffective treatment) or overdosing (toxicity and adverse effects).
• This skill is part of the 'Five Rights' of medication administration, specifically ensuring the 'Right Dose' is given.
• Nurses must always double-check their calculations, especially for high-alert medications, and have a colleague verify the calculation if required by facility policy.

How to Approach the Question

• First, identify the question as a medication calculation problem.
• Next, extract the three key pieces of information: the desired dose (what is ordered), the available dose (what is on hand), and the volume/quantity the available dose comes in.
• Recall the standard formula: (Desired Dose / Available Dose) × Quantity = Amount to Administer.
• Substitute the values into the formula: (250 mg / 500 mg) × 1 ml.
• Calculate the result: 0.5 × 1 ml = 0.5 ml.
• Finally, compare your calculated answer to the options provided and select the matching one.

Concept Tested & Keywords

• Concept Tested: Medication dosage calculation
• Stem keywords: prescription order, 250 mg, drug vial, 500 mg/ml
• Lead-in keywords: How much

Question ID

Qf_wrKrqLT1nlAOS5DUIw3

Copy ID

Reference Book

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

E6 Nursing Fundamentals Taylor p. 848-850

E6 Pharmacology Nurses Shanbhag 3e p. 52-54