Desired dose of Morphine for a patient is 0.4 mg. Dose available is 1 mg/mL. The correct formulation for this patient is:

Appeared in: NORCET 6 Prelims -2024

Explanation

The standard formula for drug dosage calculation is: (Desired Dose / Stock Concentration) x Stock Volume.
In this problem, the Desired Dose is 0.4 mg and the Stock Concentration is 1 mg in a Stock Volume of 1 mL.
Substituting the values into the formula: (0.4 mg / 1 mg) x 1 mL.
The calculation results in 0.4 mL, which is the correct volume to administer to the patient.

Option B: This is double the required dose. It would result from an incorrect calculation, possibly by multiplying the desired dose by 2 instead of dividing by the concentration.
Option C: This is half the required dose. It would result from an incorrect calculation, possibly by dividing the desired dose by 2.
Option D: This is an incorrect volume that does not correspond to the correct calculation. It likely represents a simple arithmetic error or misreading of the values.

Visual 1: Infographic - A clear visual breakdown of the drug calculation formula: (Desired Dose / Available Dose) x Volume = Amount to Administer, with each component clearly labeled.
Visual 2: Diagram - An image of a 1 mL tuberculin syringe with the plunger drawn back to the 0.4 mL mark, demonstrating how to accurately measure the calculated dose.

Clinical Relevance

Nursing practice connection: Use the key finding related to Drug Dosage Calculation to guide bedside assessment, documentation, and the next nursing action.
Accurate dosage calculation is a fundamental and non-negotiable nursing skill to prevent medication errors, which can have serious or fatal consequences for the patient.
Morphine is a high-alert medication (an opioid). This means it has a heightened risk of causing significant patient harm when used in error. Agency policies often require an independent double-check by a second nurse before administration.
What if? - If the available stock was a different concentration, for example, 2 mg/mL, the calculation would change. The correct volume would be (0.4 mg / 2 mg/mL) = 0.2 mL. This highlights the critical importance of always verifying the stock concentration before every administration.

How to Approach the Question

First, identify the three key pieces of information provided in the question: the Desired Dose (D), the Stock Strength or Dose on Hand (H), and the Stock Volume (V).
Here, D = 0.4 mg, H = 1 mg, and V = 1 mL.
Recall the standard drug calculation formula: (D / H) x V = Amount to administer.
Substitute the identified values into the formula: (0.4 mg / 1 mg) x 1 mL.
Perform the mathematical calculation: 0.4 x 1 = 0.4.
The result is 0.4 mL. Match this result with the given options to find the correct answer.

Concept Tested & Keywords

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Practise the full NORCET 6 Prelims -2024

Attempt every question from this paper in a timed mock, then review the full solution for each one.