The doctor advised injection of ceftriaxone 500 mg IV to a patient. The available stock strength is 1 gram/5 ml. How much volume of drug should the nurse administer to the patient?

1. A

   2.5 ml

2. B

   5 ml

3. C

   1 ml

4. D

   10 ml

Appeared in: DSSSB 6 September 2024

Explanation

• The core task is to calculate the correct volume of medication using the prescribed dose and the available stock strength.
• The standard formula for this calculation is: Volume = (Desired Dose / Available Dose) × Volume on Hand.
• First, all units must be consistent. The available dose of 1 gram must be converted to 1000 milligrams to match the desired dose unit.
• Plugging the values into the formula: (500 mg / 1000 mg) × 5 ml.
• This simplifies to 0.5 × 5 ml, which equals 2.5 ml.

Why Other Options Were Wrong

• Option B: Administering 5 ml would deliver the entire 1 gram (1000 mg) from the vial, which is double the prescribed dose of 500 mg.
• Option C: The concentration of the solution is 1000 mg in 5 ml, which is 200 mg per ml. Therefore, 1 ml would only provide 200 mg of the drug, which is less than half the required dose.
• Option D: Administering 10 ml would deliver 2000 mg (2 grams) of ceftriaxone, which is four times the prescribed dose and a dangerous overdose.

Related Visual

Clinical Relevance

• Nursing practice connection: Use the key finding related to Drug Dose Calculation to guide bedside assessment, documentation, and the next nursing action.
• Accurate drug calculation is a fundamental and critical nursing skill to ensure patient safety and prevent medication errors.
• Administering an incorrect dose can lead to adverse drug reactions (overdose) or therapeutic failure (underdose), both of which can have serious consequences for the patient.
• What if the available stock was 1 gram in 10 ml? The concentration would be 100 mg/ml. To give 500 mg, the nurse would need to administer 5 ml. This shows how both the dose and the volume on hand are critical for the calculation.

How to Approach the Question

• First, identify the question type. This is an analytical question requiring a mathematical calculation.
• Identify the three key pieces of information provided: the Desired Dose (D), the Available Dose or Dose on Hand (H), and the Volume on Hand (V).
• Check if the units for the Desired Dose and Available Dose are the same. If not, convert one to match the other (e.g., grams to milligrams).
• Apply the standard drug calculation formula: (D / H) x V.
• Perform the calculation to find the correct volume to administer.
• Compare your result with the given options to select the correct answer.

Concept Tested & Keywords

• Concept Tested: Drug Dose Calculation
• Stem keywords: injection, ceftriaxone, 500 mg, 1 gram/5 ml, IV, volume of drug
• Lead-in keywords: How much
• Negative lead-in flag: false

Question ID

QKaEBBesrg4WaEenZTRXVq

Copy ID

Reference Book

E6 Nursing Fundamentals Taylor p. 848-850

E6 Pharmacology Nurses Shanbhag 3e p. 55-57

E6 Nursing Fundamentals Potter Perry 12e Part 3 p. 141-143