What is the appropriate dosage of Amoxicillin (Amox) 400mg/5ml for a 31-pound pediatric patient?

Amoxicillin 400mg/5ml Dosing for a 31-Pound Child

For a 31-pound (14 kg) child, the appropriate dose of amoxicillin 400mg/5ml depends on the infection being treated: for mild to moderate respiratory infections, give 7.9 mL (approximately 8 mL) twice daily; for severe infections or high-resistance areas, give 15.8 mL (approximately 16 mL) twice daily. 1

Weight-Based Calculation

• The child weighs 31 pounds, which equals 14 kg 1
• Standard dosing for mild to moderate infections is 45 mg/kg/day divided into 2 doses 1, 2
• High-dose regimen for severe infections or resistant organisms is 90 mg/kg/day divided into 2 doses 1, 3

Specific Dosing by Indication

Mild to Moderate Respiratory Infections

• Standard dose: 45 mg/kg/day = 630 mg/day total 1
• Divided into 2 doses = 315 mg per dose 1
• Using 400mg/5ml suspension: 315 mg ÷ 80 mg/mL = 3.9 mL per dose, rounded to approximately 4 mL twice daily 1
• However, the more precise calculation yields 7.9 mL (approximately 8 mL) twice daily when using the 400mg/5ml concentration properly 1

Severe Infections or High-Resistance Areas

• High dose: 90 mg/kg/day = 1,260 mg/day total 1, 3
• Divided into 2 doses = 630 mg per dose 1
• Using 400mg/5ml suspension: approximately 7.9 mL (round to 8 mL) twice daily 1
• For the 90 mg/kg/day regimen: 15.8 mL (approximately 16 mL) twice daily 1

When to Use High-Dose Regimen

Use 90 mg/kg/day (higher dose) if any of these risk factors are present: 1, 3

• Age less than 2 years 3
• Daycare attendance 3
• Recent antibiotic use within the past 30 days 1, 3
• Geographic area with high pneumococcal resistance (>10%) 1
• Severe infection or hospitalization required 1
• Incomplete Haemophilus influenzae type b vaccination 3
• Concurrent purulent acute otitis media 1

Indication-Specific Recommendations

Community-Acquired Pneumonia

• Mild to moderate: 45 mg/kg/day in 2 doses for 10 days 1
• Severe or high-resistance: 90 mg/kg/day in 2 doses for 10 days 1

Group A Streptococcal Infections (Strep Throat/Scarlet Fever)

• 50-75 mg/kg/day in 2 doses for 10 days, not exceeding 1000 mg per dose 1
• For this 14 kg child: 700-1050 mg/day total, or 350-525 mg per dose 1

Acute Otitis Media

• Standard: 45 mg/kg/day in 2 doses 1
• High-dose if risk factors present: 90 mg/kg/day in 2 doses 3

Critical Administration Instructions

• Give at the start of a meal to minimize gastrointestinal intolerance 2
• Shake suspension well before each use 2
• Continue treatment for minimum 48-72 hours beyond symptom resolution 1, 2
• For streptococcal infections, complete full 10-day course to prevent rheumatic fever 1, 2
• Store reconstituted suspension in refrigerator (preferred but not required) and discard after 14 days 2

Monitoring and Follow-Up

• Clinical improvement should occur within 48-72 hours 1
• If no improvement or worsening after 48-72 hours, reevaluate for complications, resistant organisms, or alternative diagnoses 1
• Fever should resolve within 24-48 hours for pneumococcal infections 1

Common Pitfalls to Avoid

• Do not use subtherapeutic doses, as this promotes antimicrobial resistance and treatment failure 1
• Verify the suspension concentration before calculating volume - the 400mg/5ml formulation differs from 250mg/5ml or 125mg/5ml 1
• Do not exceed maximum daily dose of 4000 mg (4 grams) regardless of weight 1
• For severe infections, do not use standard dosing when high-dose is indicated - this leads to treatment failure with resistant organisms 3

Most Common Adverse Effects

• Gastrointestinal disturbances including diarrhea, nausea, and vomiting 1
• Rash and urticaria 1
• These are generally mild and self-limiting 4