A nurse must prepare an intravenous (IV) solution of adrenaline (epinephrine) at a 1:10,000 concentration. The stock available is a 1 mL ampule containing 1 mg of adrenaline (a 1:1,000 solution). Which method correctly prepares the required dilution?

Appeared in: NORCET 9 Prelims-2025

Explanation

The stock solution of 1:1,000 adrenaline is equivalent to a concentration of 1 mg/mL.
The target concentration of 1:10,000 for IV administration is equivalent to 0.1 mg/mL, which can also be expressed as 1 mg in 10 mL.
To achieve this, 1 mL of the stock solution (containing 1 mg of adrenaline) is drawn into a syringe.
Then, 9 mL of a diluent (like normal saline) is added to the syringe.
This results in a total volume of 10 mL containing 1 mg of adrenaline, which is the correct 1:10,000 concentration.

Option B: Mixing 1 mL of stock (1 mg) with 99 mL of saline creates a total volume of 100 mL. This results in a 1 mg/100 mL concentration, which is a 1:100,000 solution, ten times more dilute than required.
Option C: Mixing 0.1 mL of stock (containing 0.1 mg) with 10 mL of saline creates a final volume of 10.1 mL. The resulting concentration (0.1 mg / 10.1 mL) is not the standard 1:10,000 ratio and is an impractical and imprecise method of preparation.
Option D: Mixing 0.5 mL of stock (containing 0.5 mg) with 5 mL of saline creates a final volume of 5.5 mL. The resulting concentration (0.5 mg / 5.5 mL) is approximately 1:11,000, which is not the required 1:10,000 concentration.

Visual 1: Diagram: Step-by-step visual guide showing a 1 mL ampule of adrenaline being drawn into a syringe, followed by drawing 9 mL of normal saline to a total volume of 10 mL.
Visual 2: Comparison Chart: Table comparing 1:1,000 and 1:10,000 adrenaline, highlighting their concentration (mg/mL), typical route (IM vs. IV), and primary clinical use (anaphylaxis vs. cardiac arrest).

Clinical Relevance

Nursing practice connection: Knowing Drug Calculation: Adrenaline (Epinephrine) Dilution helps nurses interpret findings accurately and avoid errors in routine assessment, medication administration, and patient teaching.
Patient safety is paramount. Administering the wrong concentration of adrenaline, particularly giving the 1:1,000 strength intravenously, is a well-documented and potentially fatal medication error that can cause severe hypertension and lethal cardiac arrhythmias.
In an emergency like cardiac arrest, using a pre-filled syringe of 1:10,000 adrenaline is the safest practice as it eliminates the need for manual dilution and calculation under pressure.
Nurses must always perform independent double-checks for high-alert medications like adrenaline, where a second nurse verifies the drug, dose, and calculation before administration.

How to Approach the Question

First, identify the question as a drug dilution calculation problem.
Translate the starting and target ratio concentrations into mg/mL. Stock: 1:1,000 = 1 mg/mL. Target: 1:10,000 = 0.1 mg/mL (or 1 mg in 10 mL).
Analyze the first option: Take 1 mL of stock (which contains 1 mg of drug). Add 9 mL of diluent.
Calculate the final volume (1 mL drug + 9 mL diluent = 10 mL) and the final concentration (1 mg drug / 10 mL total volume).
Confirm that this final concentration (1 mg/10 mL) matches the target concentration.
Systematically evaluate the other options to confirm they result in incorrect concentrations.

Concept Tested & Keywords

Concept Tested: Drug Calculation: Adrenaline (Epinephrine) Dilution
Stem keywords: intravenous (IV) solution, adrenaline (epinephrine), 1:10,000 concentration, 1:1,000 solution
Lead-in keywords: Which method correctly prepares
Negative lead-in flag: false

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