What is the appropriate dosage of amoxicillin for a 20kg pediatric patient requiring 90mg/kg/day?

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Last updated: May 27, 2025 • View editorial policy

From the Guidelines

For a 20 kg child requiring 90 mg per kilogram of amoxicillin per day, the appropriate total daily dose would be 1,800 mg (90 mg/kg × 20 kg), which can be divided into 600 mg three times daily or 900 mg twice daily, as recommended by the Pediatric Community Pneumonia Guidelines 1, 2, 3, 4.

Amoxicillin Dosing

The dosing of amoxicillin is weight-based in children to ensure adequate drug concentration while minimizing side effects.

  • The 90 mg/kg/day dosing is commonly used for moderate to severe infections such as otitis media, sinusitis, or pneumonia.
  • Amoxicillin is a beta-lactam antibiotic that works by inhibiting bacterial cell wall synthesis.

Administration and Formulations

When administering amoxicillin, it's essential to complete the full prescribed course (usually 7-10 days depending on the infection) even if symptoms improve before completion.

  • The medication can be given with or without food, though taking it with food may help reduce stomach upset.
  • Common formulations include oral suspension (typically 125 mg/5 mL, 200 mg/5 mL, or 400 mg/5 mL) or chewable tablets, which should be selected based on the child's ability to take medication.

Key Considerations

  • Twice daily dosing of amoxicillin may be effective for pneumococci that are susceptible to penicillin, as noted in the guidelines 1, 2.
  • For children with a history of possible, nonserious allergic reactions to amoxicillin, treatment options include a trial of amoxicillin under medical observation or alternative antibiotics such as oral cephalosporins, levofloxacin, linezolid, or macrolides, if susceptible 4.

From the Research

Amoxicillin Dosage Calculation

To determine the appropriate amount of amoxicillin for a 20 kg child who requires 90 mg per kilogram of amoxicillin per day, we can calculate the total daily dose as follows:

  • Weight of the child: 20 kg
  • Required dosage: 90 mg/kg/day
  • Total daily dose: 20 kg * 90 mg/kg = 1800 mg

Administration Considerations

It's essential to note that the calculated dose should be divided into multiple administrations throughout the day, depending on the specific formulation and prescribing instructions. However, the provided studies do not offer specific guidance on the administration schedule for amoxicillin in pediatric patients 5, 6, 7, 8, 9.

Relevant Studies

While the studies do not directly address the calculation of amoxicillin dosage for pediatric patients, they do discuss the efficacy and safety of various antibiotics, including amoxicillin, in treating different infections 6, 8, 9. Additionally, one study reviews the spectrum and potency of orally administered cephalosporins and amoxicillin/clavulanate 9. Another study evaluates the activity of nine oral agents against gram-positive and gram-negative bacteria encountered in community-acquired infections 8.

Key Findings

  • Amoxicillin/clavulanate was found to be active against a wide range of bacterial pathogens, including Streptococcus pneumoniae, Haemophilus influenzae, and Moraxella catarrhalis 8, 9.
  • The studies do not provide specific dosage recommendations for pediatric patients, but they do highlight the importance of selecting the appropriate antibiotic based on the suspected or confirmed pathogen and the patient's individual needs 5, 6, 7, 8, 9.

References

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Guideline

Guideline Directed Topic Overview

Dr.Oracle Medical Advisory Board & Editors, 2025

Research

Efficacy and safety of cefprozil versus other beta-lactam antibiotics in the treatment of lower respiratory tract infections.

European journal of clinical microbiology & infectious diseases : official publication of the European Society of Clinical Microbiology, 1994

Professional Medical Disclaimer

This information is intended for healthcare professionals. Any medical decision-making should rely on clinical judgment and independently verified information. The content provided herein does not replace professional discretion and should be considered supplementary to established clinical guidelines. Healthcare providers should verify all information against primary literature and current practice standards before application in patient care. Dr.Oracle assumes no liability for clinical decisions based on this content.