# 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? > source: MyMerci (mymerci.kr) > url: https://mymerci.kr/pages/nclex_q.php?qn_id=543559 > language: ko > subject: Pharmacology ## 문제 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. ## 보기 1. 2.4 mL 2. 3.6 mL 3. 1.8 mL 4. 4.8 mL **✔ 정답** **정답: 4** ## 해설 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. ## 심화 해설 Step-by-Step Calculation To determine the volume for a single dose, the calculation must be performed in a specific sequence to ensure patient safety. First, the total daily dose is calculated based on the child's weight. Next, this total is divided by the number of doses per day to find the amount per single administration. Finally, the ordered mass is converted to a volume using the concentration of the available suspension. 1. Calculate the Total Daily Dose The prescription is for 45 mg/kg/day. The child weighs 12 kg. Total daily dose = 45 mg × 12 = 540 mg/day. 2. Calculate the Single Dose The total daily dose is to be divided into two equal doses. Single dose = 540 mg ÷ 2 = 270 mg per dose. 3. Calculate the Volume to Administer The available suspension has a concentration of 200 mg/5 mL. This means that every 5 mL of liquid contains 200 mg of amoxicillin. To find the volume for the 270 mg dose, a standard ratio and proportion or dimensional analysis method is used: 200 mg / 5 mL = 270 mg / X mL X = (270 mg × 5 mL) ÷ 200 mg X = 1350 ÷ 200 X = 6.75 mL. Clinical Reasoning and Safety Analysis A critical step in pediatric medication administration is the verification of the calculated dose against established safety parameters. Weight-based dosing is the standard of care in pediatrics because it accounts for developmental differences in drug metabolism and clearance, a practice necessitated by the frequent lack of commercially available, ready-to-administer formulations for children [4]. The calculated single dose of 270 mg (or 22.5 mg/kg/dose) must be cross-checked against recommended dosing guidelines for amoxicillin, which typically range from 20 to 50 mg/kg/day divided into two or three doses for common infections. The prescribed regimen falls within this standard therapeutic range. However, the volume calculation yields 6.75 mL per dose, which is not one of the provided options. This discrepancy signals that the listed options correspond to a different interpretation of the prescribed order. If the prescriber's order of "45 mg/kg/day divided into two equal doses" is misinterpreted to mean that 45 mg/kg is the amount for each of the two doses, the calculation changes drastically and unsafely. Let's examine this error pathway: a single dose would be calculated as 45 mg × 12 kg = 540 mg. The volume for this erroneous dose would be (540 mg × 5 mL) ÷ 200 mg = 13.5 mL. This volume is not among the options either. The correct answer provided, 4.8 mL, is derived from a different, hypothetical prescription or a calculation error. For 4.8 mL to be the correct single dose volume, the single dose mass would be (4.8 mL ÷ 5 mL) × 200 mg = 192 mg. For this child, 192 mg represents a dosage of 16 mg/kg/dose, or 32 mg/kg/day. This does not match the stated prescription of 45 mg/kg/day. This highlights a fundamental principle in pediatric pharmacotherapy: the extreme vigilance required when calculating and preparing extemporaneous doses. The use of a concentrated suspension (200 mg/5mL) requires a precise volume measurement, as small errors in drawing up the liquid can lead to significant overdosing or underdosing [4]. In the context of antibiotic stewardship, ensuring the exact, weight-correct dose is not only a safety issue but also a measure to combat antimicrobial resistance by avoiding sub-therapeutic dosing [1, 2]. The process demands that the nurse independently verifies the mg/kg dose against the child's weight and the clinical indication before administration, a barrier identified as crucial in preventing improper dosing .References (research sources) - [4]Extemporaneous Formulations for Pediatric Patients: Global Necessities, Challenges and Opportunities.Research articlePai VB, Nahata MC. (2026) · DOI: 10.3390/pharmaceutics18010126 ## 임상 시나리오 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. CautionAlways 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. ## 핵심 개념 - **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. ## 같은 주제 문제 - [A pediatric nurse is preparing to administer acetaminophen to a 6-year-old child weighing …](https://mymerci.kr/pages/nclex_q.php?qn_id=543558) - [A nurse is preparing to administer amoxicillin to a 4-year-old child who weighs 18 kg. The…](https://mymerci.kr/pages/nclex_q.php?qn_id=543560) --- More free questions: [기출문제](https://mymerci.kr/) _학습 참고용입니다. 실제 임상은 최신 지침과 소속 기관 프로토콜을 따르세요._