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?

Daily dose: 40 mg/kg/day × 18 kg = 720 mg/day. Per dose: 720 mg ÷ 3 = 240 mg. Using 250 mg/5 mL, proportion gives 240 mg = 4.8 mL. Other options arise from errors in weight, division, or concentration calculations.

Core Nursing Explanation Key Concept Analysis: This question tests the fundamental nursing skill of pediatric medication calculation. The core principles involve calculating a weight-based dose, dividing it by the frequency, and then converting the dose in milligrams to the correct volume of a liquid suspension using the available concentration. The formula is: (Weight × Dose per kg) ÷ Doses per day = Dose per administration in mg. Then, (Dose in mg ÷ Concentration in mg) × Volume per concentration = Dose in mL.

Answer Rationale: Let's break down the calculation step-by-step:
1. Calculate Total Daily Dose: 45 mg/kg/day × 12 kg = 540 mg/day.
2. Calculate Dose per Administration: The daily dose is divided into two equal doses. 540 mg/day ÷ 2 doses/day = 270 mg per dose.
3. Convert Milligrams to Milliliters: The suspension concentration is 200 mg per 5 mL. We set up a proportion: 200 mg / 5 mL = 270 mg / X mL. Cross-multiplying gives: 200X = 270 × 5 → 200X = 1350 → X = 1350 ÷ 200 = 6.75 mL.
Key Point! There is a critical discrepancy. The provided correct answer index (4) and the options do not match the calculation based on the problem's stated numbers (45 mg/kg, 12 kg, 200 mg/5mL). Option ④ is 4.8 mL. Let's reverse-engineer: 4.8 mL of a 200 mg/5mL suspension contains (4.8 mL ÷ 5 mL) × 200 mg = 192 mg. For a 12 kg child at 45 mg/kg/day divided BID, the dose should be 270 mg. 192 mg is incorrect. The "기존 해설" uses different numbers (40 mg/kg, 18 kg, 250 mg/5mL). Therefore, the problem statement and the answer key/options are inconsistent. Assuming the *intended* correct calculation leads to 6.75 mL, which is not among the choices. The nurse must recognize this mismatch and verify the order and calculations.

Distractor Analysis (Based on Common Calculation Errors):
Watch out for confusion!
① 2.4 mL: This might result from using the daily dose (540 mg) with the concentration but forgetting to convert mg to mL correctly, or a significant miscalculation.
② 3.6 mL: This could be an error in the weight-based calculation or an incorrect division step.
③ 1.8 mL: This is likely a major calculation error, possibly confusing mg and mL or misplacing a decimal.
④ 4.8 mL: As noted, this matches a calculation with different parameters (e.g., 40 mg/kg for an 18 kg child with 250 mg/5mL concentration, as in the old explanation). It is not correct for the given parameters.

Related Concepts: Safe medication administration is paramount. Always double-check calculations, especially for pediatric patients where doses are small and precise. Know how to use dimensional analysis or the ratio-proportion method reliably. If the calculated dose seems unreasonable or doesn't match available concentrations, the nurse must stop, re-check, and consult with the pharmacist or prescribing provider before administering.

Concept Summary

Step	Action	Example Formula
1. Daily Dose	Weight (kg) × Dose (mg/kg/day)	12 kg × 45 mg/kg/day = 540 mg/day
2. Single Dose	Daily Dose ÷ Number of Doses	540 mg/day ÷ 2 = 270 mg/dose
3. Volume per Dose	(Dose in mg ÷ mg in concentration) × mL in concentration	(270 mg ÷ 200 mg) × 5 mL = 6.75 mL

Anatomy, Physiology & Pharmacology Points • Amoxicillin: A penicillin-class antibiotic. Dosing is often weight-based (mg/kg) in pediatrics due to variable body size and metabolism. • Suspension Concentration: Always check the label (e.g., 200 mg/5 mL). Concentrations can vary (125 mg/5 mL, 250 mg/5 mL). Using the wrong concentration is a common medication error.
Memory Tips • Use the "Desire Over Have" method for dose conversion: (Desired Dose / Dose on Hand) × Volume on Hand = Volume to Administer. Here: (270 mg / 200 mg) × 5 mL = 6.75 mL. • ABCs of Safe Med Admin: Always double-check All calculations, Back-check with a colleague if unsure, and Confirm the order is appropriate for the patient's age and weight.
High-Frequency NCLEX Topics Pediatric dosage calculation is a High Yield topic. The NCLEX tests your ability to perform accurate calculations and, more importantly, your clinical judgment to recognize an incorrect or unsafe dose. If your calculation doesn't match the options or seems off, the correct action is often to re-check your work or not administer the medication until clarified.
Watch Out for Question Variations! • The question might give the total daily volume and ask for the volume per dose. • It might test if you know to round to the nearest 0.1 or 0.5 mL for administration with an oral syringe. • A follow-up question could ask: "The nurse calculates the dose. Which action should the nurse take next?" The correct answer would be to verify the calculation with another nurse before drawing up the medication.

Nursing Clinical Practice Guide Clinical Scenario: You are a nurse on a pediatric unit. A 2-year-old patient with otitis media (middle ear infection) has an order for amoxicillin 45 mg/kg/day PO divided twice daily. The child weighs 12 kg. You go to the medication room and find amoxicillin oral suspension 200 mg/5 mL.

Nursing Intervention Strategy: 1. Assessment: Verify patient identity, allergies (especially to penicillin), weight, and the medication order. Assess the child's ability to swallow liquids. 2. Calculation & Verification: Perform the calculation as shown. Since the result (6.75 mL) is an exact volume, you will draw it up using a 10 mL oral syringe. Key Point! In a real clinical setting, you would immediately have a second nurse independently double-check your calculation as per safe medication administration policies, especially for pediatric doses. 3. Administration: Shake the suspension well. Draw up the correct volume. Administer it to the child, ensuring they swallow it. You may mix it with a small amount of juice or applesauce if the child refuses, but check facility policy and ensure the child consumes the entire mixture. 4. Education & Evaluation: Educate the parents on the importance of completing the full course of antibiotics, even if symptoms improve. Instruct them on how to measure and administer the dose at home using the provided oral syringe (never a kitchen spoon). Monitor for therapeutic effect (fever reduction, decreased irritability) and for adverse effects like diarrhea or rash.

Patient Safety and Precautions: • Never estimate or round pediatric doses arbitrarily. Use precise measuring devices. • Document the administration immediately, including the exact volume given. • Monitor for signs of an allergic reaction after the first dose.
Nursing Procedure & Medication Flow Step-by-Step for Oral Liquid Medication: 1. Perform hand hygiene. 2. Check the Right patient, Right medication, Right dose, Right route, Right time, Right documentation. 3. Calculate dose and have it verified. 4. Shake the bottle. 5. Draw up medication, removing air bubbles. 6. Administer to the patient at the bedside. 7. Offer a chase of water if appropriate. 8. Document administration and any patient response.
A Word from Your Senior Nurse "Medication math can be intimidating, but it's a muscle you build with practice. In the real world, if your gut tells you a dose looks too big or too small for a tiny patient, listen to it. Stop and recalculate. Use your resources—pharmacists are your best friends for these questions. Passing the NCLEX means proving you can be trusted with these calculations. In practice, it means keeping your patients safe one careful milliliter at a time. Always remember: when in doubt, check it out!"