A pediatric nurse is preparing to administer amoxicillin to a 2-year-old toddler weighing 12 kg. The prescribed dose is 45 mg/kg/day divided into two equal doses. The available amoxicillin suspension contains 200 mg/5 mL. How many milliliters should the nurse administer for each dose?
Calculate the correct volume of amoxicillin suspension for a single dose.
12.4 mL
23.6 mL
31.8 mL
46.75 mL✓ 정답
해설
Daily dose: 45 mg/kg/day × 12 kg = 540 mg/day. Per dose: 540 mg ÷ 2 = 270 mg. Using 200 mg/5 mL, 270 mg × 5 mL ÷ 200 mg = 6.75 mL. Therefore, the nurse should administer 6.75 mL for each dose. Other options arise from errors in weight, division, or concentration calculations.
To determine the volume for a single dose, first calculate the total daily dose based on the child's weight. Then divide the daily dose by the prescribed number of doses. Finally, convert the prescribed milligram dose to milliliters using the available suspension concentration.
1. Calculate the Total Daily Dose
The prescription is for 45 mg/kg/day. The child weighs 12 kg.
Total daily dose = 45 mg/kg/day × 12 kg = 540 mg/day.
2. Calculate the Single Dose
The total daily dose is divided into two equal doses.
Single dose = 540 mg ÷ 2 = 270 mg per dose.
3. Calculate the Volume to Administer
The available suspension concentration is 200 mg/5 mL.
Volume = (270 mg × 5 mL) ÷ 200 mg
Volume = 6.75 mL.
Clinical Reasoning and Safety Analysis
The calculated single dose of 270 mg (22.5 mg/kg/dose) falls within the standard amoxicillin dosing range of 20–50 mg/kg/day divided into two or three doses. The correct volume to administer is 6.75 mL per dose. The other options (2.4 mL, 3.6 mL, 1.8 mL) correspond to 96 mg, 144 mg, and 72 mg respectively, none of which match the calculated 270 mg single dose. Nurses must always independently verify weight-based mg/kg calculations before converting to volume to prevent dosing errors.
Pediatric Amoxicillin Suspension CalculationVerifying weight-based dose and volume
For a 12 kg child, the prescribed 45 mg/kg/day yields a total daily dose of 540 mg. Divided into two equal doses, each single dose is 270 mg.
Using the suspension concentration of 200 mg/5 mL, the volume for one 270 mg dose is calculated as 6.75 mL.
Caution
Always have a second nurse independently verify the weight-based calculation and the final volume. Double-check that the dose does not exceed the recommended maximum for the child's weight and indication.
Weight-based dosing — A method of calculating medication doses for pediatric patients using body weight in kilograms (mg/kg) to ensure safe and therapeutic drug levels.
Dimensional analysis — A problem-solving method using conversion factors to move from one unit of measurement to another, ensuring accuracy in complex dosage calculations.